Webinars

Since 2011 we promote webinars which are an important aspect of our personnel development. This allows collaborators anywhere in the world to join seminars about the latest developments in several astronomical and technical fields. Webinars are presented in english and announced to a mailing list. Click here if you want to subscribe.

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Speakers 164

2017201620152014201320122011 Show All

Scheduled webinars

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04/05 - 01:00 pm BRT

Ravi Sheth ( University of Pennsylvania )

Title: to be Announced

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11/05 - 03:00 pm BRT

Peter Nugent ( University of California Berkeley )

Optimizing Transient Discovery for the Palomar Transient Factory

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18/05 - 04:00 pm BRT

Eric Huff ( Jet Propulsion Laboratory - Caltech )

Why lensing measurements are hard, and what to do about it: recent innovations from the Dark Energy Survey

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25/05 - 02:00 pm BRT

Joe deRose ( Stanford University )

Simulating the Dark Energy Survey: Catalogs to Cosmology

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01/06 - 02:00 pm BRT

Dominika Wylezalek ( Johns Hopkins University )

Observational signatures of AGN activity and feedback across cosmic time

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08/06 - 02:00 pm BRT

Angela Olinto ( University of Chicago )

The Science of POEMMA: the Probe Of Extreme Multi-Messenger Astrophysics

Past webinars

2017 06

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27/04 - 10:00 am BRT

Roberto de Propris ( University of Turku )

The New Bulge

The Milky Way is the quintessential example of a spiral galaxy and the only one whose stellar populations can be studied in detail. In particular, the bulge is the only resolved elliptical-like stellar system that we can observe, despite the extremely high foreground extinction and crowding. It has long been known that our Galaxy is a barred spiral and that our bulge belongs to the class of boxy/peanut shaped pseudobulges. We have completed the first radial velocity survey of the Southern bulge, using a total of nearly 10,000 M giants as tracers. Our study clearly shows that the entirety of the Galactic bulge is consistent with the stellar bar and no spheroidal component. We also present the first results of a new survey to probe the inner and oldest regions of the galaxy with RR Lyrae.

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20/04 - 10:00 am BRT

Fabien Lacasa ( University of Geneva )

Super-sample covariance

Current and future galaxy surveys are reaching a high signal-to-noise regime, with the detection of clusters down to low masses and the measurement of galaxy clustering and weak lensing down to small scales. In this very regime, super-sample covariance (SSC) becomes the dominant source of statistical errors, for the Large Scale Structure observables that we use to improve our cosmological understanding of the universe. I will start with a pedagogical introduction of SSC in the case of cluster counts, where the effect is usually called sample (co)variance, before examining the precision of several analytical approximations designed in the flat sky limit. Then I will present how to predict SSC for an arbitrary survey geometry, as required by surveys such as DES, LSST or Euclid with a wide coverage far from the flat sky limit. I will show that SSC is poorly estimated with classical internal covariance methods relying on the data itself, such as bootstrap or jackknife. It is also poorly estimated from subsampling a given simulation, unless said simulation is considerably larger than the survey. The latter being a challenge for future surveys covering a large portion of the observable universe such as Euclid or LSST. Beyond cluster counts, SSC also affects galaxy clustering and weak-lensing and couples observables together, thus being a particular challenge for probe combination. I will briefly explore the link between SSC and recent advances on the theoretical (soft limits and consistency relations) and simulation (separate universes) fronts, before making the case for analytical prediction of SSC as the way forward for analysis of large surveys.

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06/04 - 11:00 am BRT

Bruno Merín ( European Space Astronomy Centre )

ESASky: a new science-driven data portal for the XXI century

ESASky is a science-driven discovery portal for all ESA space astronomy missions. The first public release of ESASky features interfaces for sky exploration and for single and multiple targets searches. Using the application requires no prior-knowledge of any of the missions involved and gives users world-wide simplified access to high-level science-ready public data products from space-based Astronomy missions, plus a number of ESA-produced source catalogues. HST data, metadata and products were some of the first to be accessible through ESASky. I will highlight the latest feature that we have developed, which allows the user to project onto the sky the footprints of the JWST instruments, at any chosen position and orientation. This tool has been developed to aid JWST astronomers when they are defining observing proposals. We aim to include other missions and instruments and to expand ESASky\\\'s functionalities in the future. I will demo the tool and ask for feedback on how to make it more useful.

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30/03 - 03:00 pm BRT

Ewa Deelman ( University of Southern California )

Challenges of Managing Scientific Workflows: The Pegasus Workflow Management System

Scientific workflows allow researchers to declaratively describe potentially complex applications that are composed of individual computational components. Workflows also include a description of the data and control dependencies between the components. This talk will describe example workflows in various science domains including astronomy, bioinformatics, earthquake science, gravitational-wave physics, and others. It will examine the challenges faced by workflow management systems when executing complex workflows in distributed and high-performance computing environments. In particular the talk will describe the Pegasus Workflow Management System developed at USC/ISI (http://pegasus.isi.edu). Pegasus bridges the scientific domain and the execution environment by automatically mapping high-level workflow descriptions onto distributed resources. As part of this process, Pegasus may transform the workflow based on the workflow properties and the target architecture. The talk will describe the optimizations and techniques developed and used within the Pegasus system to efficiently manage data and computations across heterogeneous computing environments. Pegasus can execute workflows on a laptop, a campus cluster, grids, and clouds. It can handle workflows with a single task or millions of tasks and has been used to manage workflows accessing and generating Terabytes of data. The talk will also look at the challenges and opportunities that upcoming computing systems bring to workflow management systems.

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23/03 - 10:00 am BRT

Rossana Ruggeri ( University of Portsmouth )

Measuring Redshift Space Distortion in deep redshift surveys

Forthcoming galaxy redshift surveys are motivated, to a large extent, by obtaining galaxy clustering measurements to accurately quantify the observed acceleration in the expansion of the Universe. It is to be hoped that these observations will reveal insight into the physical mechanism responsible for the cosmic acceleration, be it a new scalar field currently contributing to the energy budget of the Universe as Dark Energy, modification of gravitational laws on cosmological scales, or an unknown alternative to the Standard Cosmological Model. The statistical precision afforded by forthcoming surveys including DESI and Euclid is impressive and will push at least an order of magnitude beyond current measurements. However this promised low statistical errors will only be realised with the development of new, fast, analysis methods that reduce potential systematic problems to low levels. We present an efficient method for measuring the evolution of the growth of structure using Redshift Space Distortions (RSD), that removes the need to make measurements in redshift shells. We provide sets of galaxy-weights that cover a wide range in redshift, but are optimised to provide differential information about cosmological evolution. These are derived to optimally measure the coefficients of a parameterisation of the redshift-dependent matter density, which provides a framework to measure deviations from the concordance LCDM cosmology, allowing for deviations in both geometric and/or growth. We test the robustness of the weights by comparing with alternative schemes and investigate the impact of galaxy bias.

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16/03 - 10:00 am BRT

Paolo Tanga ( Observatoire de la Côte d\'Azur )

Gaia and the asteroid population: a revolution on Earth, coming from space

The ESA Gaia mission is performing since summer 2014 an all-sky survey of all sources brighter than V~20. Most of them are stars (more than one billion), but many Solar System object are also present: 350,000 asteroids, some TNOs, comets and planetary satellites. The main science driver of Gaia is provided by the unprecedented astrometric accuracy and the physical characterization by spectro-photometry for all sources. For the Solar System, these data represent the richest homogeneous survey available, providing access to an incredible variety of properties and potentially leading to major breakthroughs in asteroid science. Also, Gaia stellar astrometry in general is going to heavily impact ground-based observations, as a completely new calibration of the sky is accessible. Some simple exploitations of the first intermediate data release published in September 2016, already show the improvements brought to ground-based astrometry of asteroids, and demonstrate the completely renewed role of stellar occultations, an impressive tool of exploration whose efficiency is being multiplied by a large factor.

2016 35

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15/12 - 04:00 pm BRT

Frossie Economou ( LSST )

It’s 10pm - do you know where your data are?

Data management in astronomy has undergone a series of radical transformations in living memory. While much of that has been because of the evolution of computing itself, the demands of astronomical processing have sometimes led ahead and sometimes lagged behind the capabilities of commodity IT. This talk is a personal view on how current developments in cloud computing are affecting the landscape of data processing and data publication, and what we can learn about past experiences to best take advantage of new trends in platforms and software engineering. I’m also going to share some practical lessons learned drawn from engaging with the commodity computing landscape within LSST’s Science Quality and Reliability Engineering (SQuaRE) team.

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08/12 - 12:00 pm BRT

William Nielsen Brandt ( Penn State University )

Supermassive Black Hole Studies with the LSST

Data from the Large Synoptic Survey Telescope (LSST) will enable multiple breakthrough investigations of active galactic nuclei (AGNs) as well as typically dormant supermassive black holes (SMBHs). I will describe how the decade-long LSST main survey will discover at least 20 million AGNs across 18,000 deg^2, obtaining 60-180 visits per source for each of the ugrizy filters. Several extragalactic LSST Deep-Drilling Fields will provide even deeper coverage and denser temporal sampling for about a hundred thousand AGNs. Efficient AGN identification from z = 0-7.5 will be possible via a combination of techniques: color selection, variability selection, lack of proper motion, differential chromatic refraction patterns, and multiwavelength matching. I will also describe a few of the prime SMBH science investigations that LSST will enable including (1) massive investigations of AGN variability, (2) studies of transient SMBH fueling events, and (3) the identification of large AGN samples at high redshifts.

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07/12 - 03:00 pm BRT

Mario Juric ( University of Washington/LSST )

LSST Data Spaces: Access, Visualization, and Analysis of LSST Datasets

The LSST will deliver two primary classes of data products: the near-real time stream of alerts to changes in the sky (so called \\\"Level 1” products), and the annual, systematics limited, reprocessing of the entire data sets (so called “Level 2” products, the \\\"Data Releases”). The scale of both of these products, but especially Level 2 (~few petabytes), will stress the ability of the users to download and analyze on their laptop. The LSST is therefore building a system to make it possible to perform some of the visualization and data analysis remotely. This environment, currently envisioned to be based on well known tools such as JupyterHub, will enable users to engage in interactive analysis (or run their analysis codes) at the LSST data center. Through it, the users will have access to fast database space, file storage, as well as a medium-scale computing cluster. In this talk, I will discuss our plans for such an environment -- a “data space” in which research with LSST data could be performed, and added value (“Level 3”) data products created.

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01/12 - 02:00 pm BRT

Jeff Newman ( University of Pittsburgh )

The Future of Ground-Based Astronomy in the US

In this talk, I will summarize the results of two different efforts to determine how the US can best leverage the large upcoming surveys from DESI and LSST: the National Science Foundation-requested Kavli/NOAO/LSST report and the US Department of Energy-requested Cosmic Visions report. I will attempt to lay out the landscape of what observational resources may be available in the next decade and beyond. I will particularly focus on a project at the intersection of these two reports, a Southern Spectroscopic Survey Instrument (SSSI).

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24/11 - 11:00 am BRT

Luiz Nicolaci da Costa ( LIneA )

BPG-LSST: motivação, filosofia, organização e objetivos

Nesta apresentação a motivação, filosofia, organização e objetivos para a formação do BPG-LSST serão discutidos. Alguns aspectos sobre o projeto LSST e o acordo que permitiu a participação deste grupo no LSST também serão apresentados. Finalmente, a importância de que o trabalho do BPG seja coordenado será enfatizada. Ao final da apresentação perguntas e comentários são bem vindos.

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17/11 - 04:00 pm BRT

Ashish Mahabal ( Caltech )

The LSST Informatics and Statistics Science Collaboration: Activity at the SAMSI ASTRO Program

We will describe activity taking place as part of the year-long Program on Statistical, Mathematical and Computational Methods for Astronomy (ASTRO) at the Statistical and Applied Mathematical Sciences Institute (SAMSI). ASTRO hosts five working groups covering several topics in astrostatistics relevant to LSST science. We will provide an overview of activity in WG2 (Synoptic Time Domain Surveys), WG3 (Multivariate and Irregularly Sampled Time Series), and WG4 (Astrophysical Populations). WG2 has a number of subgroups covering setting up a data challenge, light-curve decomposition, incorporating ancillary information, outlier detection etc.. WG3 is covering time series topics arising in gravitational wave, exoplanet, and synoptic survey astronomy. WG4 is so far focusing on population studies for exoplanets, but is also covering science and methods relevant to LSST. An interesting area of overlap between WG3 and WG4 is the statistical area of functional data analysis (FDA): how to do statistics with populations of functions, rather than of scalars or small, fixed-length vectors (as in luminosity function estimation). Working Groups mostly meet remotely; some subgroups will become active only after the New Year, providing opportunities for new participants to join in some areas. Ashish Mahabal (Caltech) and Tom Loredo (Cornell University)

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17/11 - 04:00 pm BRT

Tom Loredo ( Cornell University )

The LSST Informatics and Statistics Science Collaboration: Activity at the SAMSI ASTRO Program

We will describe activity taking place as part of the year-long Program on Statistical, Mathematical and Computational Methods for Astronomy (ASTRO) at the Statistical and Applied Mathematical Sciences Institute (SAMSI). ASTRO hosts five working groups covering several topics in astrostatistics relevant to LSST science. We will provide an overview of activity in WG2 (Synoptic Time Domain Surveys), WG3 (Multivariate and Irregularly Sampled Time Series), and WG4 (Astrophysical Populations). WG2 has a number of subgroups covering setting up a data challenge, light-curve decomposition, incorporating ancillary information, outlier detection etc.. WG3 is covering time series topics arising in gravitational wave, exoplanet, and synoptic survey astronomy. WG4 is so far focusing on population studies for exoplanets, but is also covering science and methods relevant to LSST. An interesting area of overlap between WG3 and WG4 is the statistical area of functional data analysis (FDA): how to do statistics with populations of functions, rather than of scalars or small, fixed-length vectors (as in luminosity function estimation). Working Groups mostly meet remotely; some subgroups will become active only after the New Year, providing opportunities for new participants to join in some areas. Ashish Mahabal (Caltech) and Tom Loredo (Cornell University)

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03/11 - 05:00 pm BRT

Masao Sako ( University of Pennsylvania )

Exploring the Transient Sky with the Dark Energy Survey

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27/10 - 10:00 am BRT

Koenraad Kuijken ( Leiden Observatory )

Cosmology with the KiDS weak lensing survey

The Kilo-Degree Survey (KiDS) is mapping 1500 square degrees of sky using the ESO VLT Survey Telescope, a wide-field imaging telescope on Paranal. I will discuss the recent results presented in Hildebrandt et al (2016, 1606.05338) from a tomographic analysis of the matter power spectrum using weak gravitational lensing, as well as the implications of the measurements for cosmology.

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20/10 - 11:00 am BRT

Federica Bianco ( NYU Center for Urban Science and Progress )

The transient sky and LSST

I will review the many scientific topics on transient and variable sky in which members of our collaboration are world-leading experts, from geometric transits to nuclear explosions, and give a brief overview of the expected and wished for results LSST could provide, and of the work needed to do to assure LSST\\\'s potential to explore the transient sky is unleashed.

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13/10 - 10:00 am BRT

Ivan Minchev ( Astrophysical Institute Potsdam (AIP) )

New results from the APOGEE survey and their interpretation using a Milky Way chemo-dynamical model

One of the central questions of Galactic astrophysics is how galaxies form and evolve. The galaxy we can study in detail like no other is our own Milky Way. To this end, a number of ground-based spectroscopic and photometric Galactic surveys have been planned or currently ongoing. The Gaia DR1 is already complementing some of these (RAVE, APOGEE) with accurate proper motions and parallaxes. I will present recent observational results from the near-infrared spectroscopic survey APOGEE, which I will interpret using a chemo-dynamical model tailored to the Milky Way. I will argue that to break degeneracy among different Galactic evolution scenarios we need accurate stellar ages, such as those obtained through asteroseismology by the CoRoT and Kepler missions.

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06/10 - 01:00 pm BRT

Lucianne Walkowicz ( Adler Planetarium - LSST Science Collaboration Coordinator )

An Overview of the LSST Science Collaborations

The LSST Science Collaborations are topical working groups of international scientists, who work together to provide scientifically-motivated feedback to survey implementation, develop software and data products to enable LSST science, and organize follow-up and analysis resources in preparation for LSST\'s first light. In this talk, I will discuss the structure of the science collaborations, their current activities, and how new LSST members can join the thriving collaboration community.

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29/09 - 10:00 am BRT

Marc Huertas-Company ( Observatoire de Paris )

Mass assembly and morphological transformations since z~3

The life of a galaxy is a balance between processes that trigger star formation by accelerating gas cooling and others which tend to prevent stars to form by expelling or heating gas. Over the past years, the picture is emerging that, during most of its life, a galaxy seems to live a rather quiet life, gradually growing in stellar mass through the formation of new stars which are formed at a rate remarkably proportional to its stellar mass, This is interpreted as an indirect evidence that fuel in the form of cold gas is somehow continuously being fed into the galaxies to sustain star formation. Two major events, eventually related, can break this apparent equilibrium. An episode of high star formation activity (e.g starburst) can be triggered. Or, suddenly something might happen that prevents the galaxy to continue forming new stars. Quenching is probably the most important event that a galaxy experiences during its life and a fundamental mechanism that helps understanding most of the properties of our surrounding Universe. There are a variety of different mechanisms entertained for the quenching process, e.g. feedback, interactions, halo driven shock heating, morphological quenching etc. Which one is dominantly driving galaxy evolution (if there is) or under which circumstances one or another process is triggered is still a mystery. In my talk I will focus on the relation between structure and quenching in massive galaxies. By using advanced machine intelligence techniques, I will analyze the relation between quenching and bulge growth in massive galaxies from z~3. I will in fact show evidences of two distinct channels for the growth of bulges in the massive end of the present day Hubble sequence (Huertas-Company+15ab).

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22/09 - 02:00 pm BRT

Alexander Mead ( University of British Columbia )

The halo model and cosmological power spectra

Cosmological weak gravitational lensings surveys use the correlated distortions of galaxy shapes to infer properties of the matter distribution in the Universe. In principle, these measurements may then be used to constrain theories of the accelerated expansion, to infer the neutrino mass, and to learn about baryonic feedback processes. However, the interpretation of weak lensing data is complicated by the fact that non-linear structure along the line-of-sight contributes to the lensing signal. In this talk I will discuss how to model the non-linear matter distribution using N-body simulations and analytical techniques.

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15/09 - 12:00 pm BRT

Ashley Ross ( Ohio State University )

Results from the Completed SDSS-III Baryon Oscillation Spectroscopic Survey

Galaxy surveys allow answers to fundamental questions such as: What is the nature of Dark Energy? Can we detect deviations from General Relativity (GR)? What is the mass of the neutrino(s)? I will explain how using examples of measurements made using the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS). I will describe the BOSS data, the methods we use to measure the clustering of BOSS galaxies, and how our most recent clustering measurements have allowed us to measure the distance to BOSS galaxies to within 1% precision. I will further describe some of the technical challenges and systematic concerns in our analysis, and the methods and measurements we have used to ameliorate these concerns. I will then discuss the early results from the Dark Energy Survey and the extended BOSS, both of which are in the early phases of data analysis/operation. I will conclude with a discussion of the results that will be afforded by future surveys, such as DESI.

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25/08 - 11:00 am BRT

Yuanyuan Zhang ( Fermilab )

Understanding Cluster Central Galaxies with the Dark Energy Survey

Galaxy clusters are important subjects of study for both cosmology and astrophysics research. Ongoing optical surveys like the Dark Energy Survey (DES) are observing tens of thousands of clusters to redshift 1.0 and beyond. The evolution of cluster central galaxies is one topic that will benefit from the statistical power of DES data. The LambdaCDM model provides the big picture explanation for the formation of cluster galaxies. However, astrophysical processes like in situ star formation, stripping and disruption are critical in shaping the galaxies’ properties. In this webinar, I will present studies about cluster central galaxies with DES data. I will also discuss the high redshift prospect of the topic, utilizing the discovery power of DES on z > 1.0 clusters.

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23/08 - 02:00 pm BRT

Angelo Fausti ( LIneA/LSST )

O Portal Científico: Uma ferramenta para analisar dados de grandes levantamentos astronômicos

Nesta apresentação o atual status do portal científico sendo desenvolvido nos últimos oito anos pelo LIneA é revisto. O objetivo do portal é permitir ao pesquisador explorar de uma forma eficiente o grande volume de dados sendo gerados pelos grandes levantamentos astronômicos. Ele foi concebido para atender as necessidades do DES, mas pode ser facilmente estendido para atender as necessidades de pesquisadores envolvidos na análise de simulações numéricas e de dados na era do LSST

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18/08 - 12:00 pm BRT

Alex Drlica-Wagner ( Fermilab )

Fundamental Physics with the Smallest Galaxies

The population of Milky Way satellite galaxies includes the least luminous, least chemically evolved, and most dark matter dominated galaxies in the known universe. Due to their proximity, high dark matter content, and low astrophysical backgrounds, dwarf spheroidal galaxies are unique probes of cosmology and promising targets for indirect searches for dark matter. Prior to 2015, roughly two dozen dwarf spheroidal galaxies were known to surround the Milky Way. Since the beginning of last year, new optical imaging surveys have discovered over twenty new dwarf galaxy candidates, potentially doubling the population of Milky Way satellite galaxies in a single year. I will discuss recent optical searches for dwarf galaxies, focusing specifically on results from the Dark Energy Survey (DES) and the implications for gamma-ray searches for dark matter annihilation with the Fermi Large Area Telescope.

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11/08 - 12:00 pm BRT

Eric Baxter ( UPenn )

New Methods for Measuring the Masses of Galaxy Clusters

Clusters of galaxies are the most massive gravitationally bound structures in the Universe. The abundance of these rare objects is very sensitive to cosmological parameters such as the equation of state of dark energy. However, exploiting the full power of galaxy clusters as cosmological probes requires accurate constraints on their masses. In this talk, I will describe two relatively new but potentially powerful approaches to constraining the masses of galaxy clusters: gravitational lensing of the Comic Microwave Background and cluster clustering.

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04/08 - 12:00 pm BRT

Edmond Cheung ( Kavli IPMU )

Suppressing star formation in quiescent galaxies with supermassive black hole winds

Quiescent galaxies with little or no ongoing star formation dominate the population of galaxies with masses above 2 × 10^10 M_sun; the number of quiescent galaxies has increased by a factor of about 25 over the past ten billion years. Once star formation has been shut down, perhaps during the quasar phase of rapid accretion onto a supermassive black hole, an unknown mechanism must remove or heat the gas that is subsequently accreted from either stellar mass loss or mergers and that would otherwise cool to form stars. Energy output from a black hole accreting at a low rate has been proposed, but observational evidence for this in the form of expanding hot gas shells is indirect and limited to radio galaxies at the centres of clusters, which are too rare to explain the vast majority of the quiescent population. In this talk, we report bisymmetric emission features co-aligned with strong ionized-gas velocity gradients from which we infer the presence of centrally driven winds in typical quiescent galaxies that host low-luminosity active nuclei. These galaxies are surprisingly common, accounting for as much as ten per cent of the quiescent population with masses around 2 × 10^10 times that of the Sun. In a prototypical example, we calculate that the energy input from the galaxy’s low-level active supermassive black hole is capable of driving the observed wind, which contains sufficient mechanical energy to heat ambient, cooler gas (also detected) and thereby suppress star formation.

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28/07 - 02:00 pm BRT

Lindsay Bleem ( Argonne National Laboratory )

Constraining Cosmology using Galaxy Clusters in the SPT-SZ Survey

Galaxy clusters are powerful tools with which to constrain cosmological models as their abundance depends upon both the expansion history of the universe and the growth of density fluctuations. In this talk, I will describe the ongoing program by the South Pole Telescope collaboration to test such models using a sample of massive clusters identified in the SPT-SZ survey. One of the primary objectives of this 2500-square-degree mm-wavelength survey was the construction of a mass-limited sample of galaxy clusters identified via the thermal Sunyaev- Zel’dovich (SZ) effect (through which clusters imprint small temperature distortions on the cosmic microwave background). I will describe the galaxy cluster sample, efforts to improve understanding of the mass-calibration of cluster observables, as well as our newly-published cosmological constraints. Finally, there is a wealth of information that can be extracted from analyses of clusters using multi-wavelength data such as from the SPT and the optical-wavelength Dark Energy Survey. I will highlight several such ongoing projects.

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21/07 - 12:00 pm BRT

Adriano Pieres ( UFRGS )

The Magellanic Clouds outer regions

The Magellanic Clouds (composed by the Large and the Small Magellanic Cloud) are the most luminous and largest dwarf galaxies satellites of the Milky Way. In its first infall towards the Galaxy, they are a rich laboratory to study the star formation, the galactic evolution and its geometry. The Magellanic Clouds present a strong interaction between LMC-SMC in the last Gyrs, forming the Magellanic Bridge (a bridge of gas, stars and clusters linking SMC and LMC) and the Magellanic Stream (a gas strip spanning at least 200 degrees on the sky). In this talk, beyond a brief review of Magellanic System I will present our main results about the outer LMC star clusters covered by Dark Energy Survey: the discovery of 28 new clusters, the age distribution and the age-metallicity relationship for a sample of 117 clusters.

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14/07 - 10:00 am BRT

Juan Garcia-Bellido ( Universidad Autónoma de Madrid )

Gravitational Waves from Primordial Black Holes as Dark Matter

Twenty years ago, we predicted that primordial black holes would form via the gravitational collapse of matter associated with peaks in the spectrum of fluctuations, and that they could constitute all of the dark matter today. More recently, we predicted the mass distribution of PBH, which peaks at 50 Msun and whose tails could be responsible for the seeds of galaxies. LIGO has recently detected gravitational waves from the inspiraling of two 30 Msun black holes. In arXiv:1603.05234, we propose that LIGO has actually detected dark matter in the form of PBH, and predict that within 10 years, an array of GW detectors (i.e. LIGO, VIRGO, KAGRA, INDIGO, etc.) could be used to determine the mass distribution of PBH dark matter with 10% accuracy.

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23/06 - 02:00 pm BRT

Joel Primack ( University of California, Santa Cruz )

New Insights on Galaxy Formation from Observations and Simulations

Large-scale simulations track the evolution of structure in the ΛCDM universe of dark energy and cold dark matter on scales of billions of light years, and cosmological zoom-in simulations model how individual galaxies evolve through the interaction of baryonic matter and dark matter. New large-scale simulations based on the latest cosmological parameters are being used in novel ways to predict the rate of star formation and the distribution of galaxies with various properties across cosmic time. Astronomers used to think (1) that galaxies are a combination of stellar disks and spheroids, like nearby galaxies; (2) that galaxies are mostly smooth (the largest lumps in the Milky Way are globular clusters and giant molecular clouds, each with a maximum mass about a million times the mass of the sun); and (3) that galaxies mostly grow in radius as they grow in mass. New discoveries from CANDELS, the biggest-ever Hubble Space Telescope program, have shown that all three are wrong! Instead, by comparing zoom-in galaxy simulations with CANDELS observations, we have found that (1) most galaxies start elongated (zucchini-shaped) and only later become rounder as their centers become dominated by baryonic matter; (2) most star-forming galaxies in the early universe have giant clumps of stars with masses of a hundred million solar masses or more; and (3) forming galaxies sometimes undergo a period of rapid shrinkage in the radius that encloses half their light as they grow in mass, a process that we call “compaction”. New telescopes including James Webb Space Telescope will no doubt lead to further insights on structure formation in the universe.

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16/06 - 10:00 am BRT

Francisco “Fubica” Vilar Brasileiro ( Universidade Federal de Campina Grande )

Executando Aplicações Científicas em uma Federação de Nuvens Computacionais Privadas

O paradigma de computação na nuvem vem revolucionando a forma como as pessoas passaram a atender as suas demandas computacionais. Ao invés de implantar suas próprias instalações, os usuários podem recorrer a provedores de computação na nuvem de acesso público, como Amazon Web Services, Microsoft Azure e Google App Engine para implantar, sob demanda, infraestruturas computacionais customizadas para seus propósitos específicos, que podem ser rapidamente comissionadas e depois desmanteladas, pagando apenas pelo custo da infraestrutura durante o período de tempo em que a mesma foi utilizada. Esse modelo não só agiliza a implantação de infraestruturas, mas pode também significar enormes economias para o usuário. Em uma escala menor, organizações que já têm uma infraestrutura computacional própria podem usar tecnologias similares às usadas pelos provedores de computação na nuvem de acesso público para prover um serviço equivalente voltando para seus usuários internos, ou seja, transformando-se em provedores de computação na nuvem de acesso privado. Nesse caso, por um lado as vantagens de rápido provisionamento continuam sendo oferecidas aos usuários internos, enquanto por outro lado a infraestrutura compartilhada entre os vários usuários da organização pode ser melhor aproveitada, reduzindo o custo de implantação e operação da mesma. Nesse webminar eu irei falar sobre as tecnologias que podem ser usadas para implantação de provedores de computação na nuvem de acesso privado, como essas infraestruturas podem ser usadas para dar suporte à execução de aplicações científicas e como nuvens computacionais de várias organizações podem ser federadas para oferecer ainda mais recursos e de forma mais eficiente. O webminar apresentará exemplos de uso de nuvem privada baseada no Openstack, enquanto que a Nuvem Acadêmica Federada, um serviço experimental operado pela UFCG com apoio da RNP, será usada para exemplificar o uso de uma federação de nuvens computacionais acadêmicas.

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09/06 - 10:00 am BRT

Jonathan Loveday ( University of Sussex )

Galaxy and Mass Assembly (GAMA): Small scale anisotropic galaxy clustering and the pairwise velocity dispersion of galaxies

The Galaxy and Mass Assembly (GAMA) survey provides an unprecedented database for detailed study of galaxies in the nearby (z < 0.5) Universe by combining imaging data from UV to radio and highly-complete spectroscopy to r = 19.8 mag. I will briefly summarise the current status of the GAMA survey and present some key results. I will then describe some work in progress to characterise the galaxy pairwise velocity dispersion to smaller scales than has hitherto been possible, and how such measurements may in future place stringent constraints on modified gravity models.

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02/06 - 10:00 am BRT

Fabricio Ferrari ( FURG )

Morfometryka — A New Way of Establishing Morphological Classification of Galaxies

We present an extended morphometric system to automatically classify galaxies from astronomical images. The new system includes the original and modified versions of the CASGM coefficients (Concentration $C1$ , Asymmetry $A_3$ , and Smoothness $S_3$ ), and the new parameters entropy, $H$, and spirality $\\sigma\\psi$. The new parameters $A_3$ , $S_3$ , and $H$ are better to discriminate galaxy classes than $A_1$ , $S_1$ , and $G$, respectively. The new parameter $\\sigma_psi$ captures the amount of non-radial pattern on the image and is almost linearly dependent on T-type. Using a sample of spiral and elliptical galaxies from the Galaxy Zoo project as a training set, we employed the Linear Discriminant Analysis (LDA) technique to classify EFIGI (Baillard et al. 4458 galaxies), Nair & Abraham (14,123 galaxies), and SDSS Legacy (779,235 galaxies) samples. The cross-validation test shows that we can achieve an accuracy of more than 90\\% with our classification scheme. Therefore, we are able to define a plane in the morphometric parameter space that separates the elliptical and spiral classes with a mismatch between classes smaller than 10\\%. We use the distance to this plane as a morphometric index ($M_i$) and we show that it follows the human based T-type index very closely. We calculate morphometric index M i for ∼780k galaxies from SDSS Legacy Survey–DR7. We discuss how M i correlates with stellar population parameters obtained using the spectra available from SDSS–DR7. We discuss two science cases. We apply the morphometric system together with photometric analysis to discriminate classical from pseudo bulges in a sample of $\\sim$1000 SDSS galaxies from Gadotti (2009). Also, we compare morphometry and kinemtics for CALIFA survey galaxies.

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19/05 - 02:00 pm BRT

Roberto Souto ( LNCC )

Supercomputador Santos Dumont: ambiente computacional petaflópico para pesquisa científica no Brasil

O supercomputador Santos Dumont (SDumont) possui capacidade instalada de processamento na ordem de 1,1 Petaflop/s, apresentando uma configuração híbrida de nós computacionais, no que se refere à arquitetura de processamento paralelo disponível. A chegada de uma máquina deste porte, possibilita aos pesquisadores do país realizarem experimentos e simulações, em uma escala de grandeza que não seria factível com os recursos computacionais para pesquisa disponíveis no Brasil até então. Nesta palestra iremos abordar aspectos tais como a configuração dos nós computacionais, as políticas de alocação de recursos implementadas, e alguns detalhes sobre a operação da máquina até o momento.

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05/05 - 10:00 am BRT

William Hartley ( University College London )

Modelling photo-z in current and future imaging dark energy experiments

There are a number of ambitious ongoing and forthcoming cosmological experiments utilizing information contained within multiple broadband images of galaxies. Among the most important measurable quantities in these surveys are the distances to the galaxies used for a weak lensing or BAO analysis via their photometric redshift. Two approaches are typically taken to the problem of deriving photo-z: modelling the galaxy population and using machine learning techniques to directly map from the photometry to the likely redshift. Machine learning methods are proving to be the more powerful presently, but face fundamental difficulties in the future due to the lack of spectroscopic information. It is vital, then, that modelling methods become competitive. In this webinar I will outline some of the major challenges and necessary developments in pursuit of this goal.

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28/04 - 02:00 pm BRT

Filipe Abdalla ( University College London )

Using cross correlations for calibrating cosmology in with photometric redsfhit surveys

Using photometric redsfhits can be a very statistically useful comsological probe for large scale structure. I will show how we shoudl be able to make great advances in this area by in order to measure the neutrino mass. However calibration of the order of 10^-3 has to be achieved otherwise there will be a large cosmological bias. I will show how to perform a joint analysis in order to calibrate fully the photometric redsfhit sfor the next geenration of data including the Dark nenergy survey and Euclid.

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14/04 - 10:00 am BRT

Francisco Castander ( Institut de Ciències de l’Espai )

The PAUCamera and Survey

PAUCam is new wide field imaging instrument that has been recently commissioned at the WHT telescope. PAUCam is equipped with 40 narrow band filters and 6 broad band filters. It has the capabilty of delivering accurate photometric redshifts. I will talk about the capabilities of the instrument and the PAU Survey that we are starting. The science case of PAUS is based on the combination of clustering and lensing observables.

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07/04 - 10:00 am BRT

Bhuvnesh Jain ( University of Pennsylvania )

Lensing measurements of galaxies, voids and the CMB: tests of the standard cosmological model

I will show weak lensing results from the Sloan Digital Sky Survey and the Dark Energy Survey. We use new methods to measure the mass distribution and clustering of cosmic voids and the shapes of galaxy halos. With the Dark Energy Survey, we have made wide field mass maps and related the galaxy distribution to the lensing mass, including CMB lensing. Ideas that provide alternatives to the standard cosmological model include the possibility that gravity on large scales deviates from general relativity or that dark matter has new interactions. I will describe how a variety of measurements are used to pursue such new physics.

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31/03 - 01:00 pm BRT

Rita Tojeiro ( St. Andrews )

Unlocking the full potential of galaxy spectroscopic surveys

The great era of massive galaxy spectroscopic surveys has opened many doors across galaxy evolution and observational cosmology studies. Accurate three-dimensional positions of millions of galaxies allow us to map the large-scale structure and expansion history of the Universe. In parallel, galaxy spectra allow us to infer many physical properties of galaxies, including their time-resolved star-formation histories. In this webinar I will show how combining these two probes – the large-scale structure and time-resolved star-formation histories – offers a unique perspective in helping us answer a variety of questions, from the growth rate of structure to halo assembly bias.

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10/03 - 02:00 pm BRT

Friedrich Anders ( Potsdam )

APOGEE, Archaeology and Asteroseismology

The Apache Point Observatory Galactic Evolution Experiment (APOGEE) was designed to discover new terrain – by taking high-resolution infra-red spectra of red giants throughout the heavily obscured Galactic midplane. I will present some recent APOGEE results in terms of Galactic Archaeology and its synergies with asteroseismology. Finally, I will discuss science that will be possible with APOGEE-2 and by combining APOGEE with Gaia and K2 data, with a focus on projects with Brazilian involvement.

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03/03 - 10:00 am BRT

Roy Maartens ( Portsmouth and University of Western Cape )

Cosmology with the SKA

The Square Kilometre Array will be the world’s largest astronomy experiment in the next decades. It will open up a new era of cosmology, mapping the Universe on the largest scales in the radio. I will describe the different surveys planned with the SKA, and what we can expect to learn from these surveys.

2015 31

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04/12 - 04:00 pm BRT

Jake VanderPlas ( University of Washington eScience Institute )

Astrostatistics: Opening the Black Box

The large datasets being generated by current and future astronomical surveys give us the ability to answer questions at a breadth and depth that was previously unimaginable. Yet datasets which strive to be generally useful are rarely ideal for any particular science case: measurements are often sparser, noisier, or more heterogeneous than one might hope. To adapt tried-and-true statistical methods to this new milieu of large-scale, noisy, heterogeneous data often requires us to re-examine these methods: to pry off the lid of the black box and consider the assumptions they are built on, and how these assumptions can be relaxed for use in this new context. In this talk I’ll explore a case study of such an exercise: our extension of the Lomb-Scargle Periodogram for use with the sparse, multi-color photometry expected from LSST. For studies involving RR-Lyrae-type variable stars, we expect this multiband algorithm to push the effective depth of LSST two magnitudes deeper than for previously used methods.

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19/11 - 02:00 pm BRT

Erik Tollerud ( Space Telescope Science Institute )

The Development of Astropy and Using it to Identify Local Volume Dwarf Galaxies

I will describe the Astropy Project, a community library for Python in Astronomy. I will describe the origins of Astropy, as well as some key aspects of how we develop Astropy. I will further discuss how this (along with other factors) has lead to the explosive growth of the Astropy community since the project’s inception. I will then discuss an effort I have been leading recently to identify nearby (Local Volume) dwarf galaxies, and describe how many of the critical steps were enabled by Astropy and its affiliated packages.

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05/11 - 02:00 pm BRT

Robin Ciardullo ( Penn State University )

HETDEX and the Star-Forming Galaxies of the z ~ 2 Universe

In a few months, the Hobby Eberly Telescope Dark Energy Experiment will begin obtaining redshifts for roughly a million Ly-alpha emitting galaxies (LAEs) between 1.9 < z < 3.5. While the main purpose of the project is to study the evolution of Dark Energy, the project will produce an incredible data base for studies of galaxy evolution. In preparation for this, we have been investigating the physical and chemical properties of emission-line galaxies in the z ~ 2 universe, using LAEs discovered from the ground and samples of [O III]-emitting objects identified from space. We show that LAEs are not “low mass, dust-poor galaxies caught in the act of formation”, but instead normal star-forming galaxies with stellar masses that span almost the entire galaxy mass range, from at least 7.5 < log M/Msun < 10.5. We use our z ~ 2 galaxy samples to explore issues such as the relationship between stellar mass and metallicity, the systematics of star-formation rate indicators, the behavior of dust attenuation laws versus stellar mass, and the question of what makes an LAE and LAE.

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29/10 - 01:00 pm BRT

Anthony Gonzalez ( University of Florida )

The Massive and Distant Clusters of WISE Survey

The Massive and Distant Clusters of WISE Survey (MaDCoWS) is a comprehensive program to detect and characterize the most massive galaxy clusters in the Universe at z~1 over the full extragalactic sky. In this talk I will give an overview of the survey and present the status of our search within the PanSTARRS footprint, which has yielded several thousand candidate clusters. I will demonstrate that MaDCoWS is efficiently isolating the cluster population at this epoch, and present recent results from targeted follow-up observations, including confirmation of the second most massive galaxy cluster known at z>1. Finally, I will discuss our ongoing Spitzer program to image nearly 2000 MaDCoWS candidates and discuss potential improvement from incorporation of new data sets.

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22/10 - 01:00 pm BRT

Dustin Lang ( Carnegie Mellon University, University of Waterloo )

The DECam Legacy Survey: image reductions using The Tractor

The Dark Energy Camera (DECam) Legacy Survey is a mid-size survey of about 6000 square degrees of the equatorial sky in g,r,z filters to 2 mags deeper than SDSS. These images overlap millions of spectra from SDSS and BOSS, so should be useful for a variety of science cases. It is a public survey: the raw images have zero proprietary period, and we aim to do public data releases every 6 months. I’ll introduce the survey and the data reduction approach we’re using: a forward-modeling code called the Tractor, which allows us to make simultaneous measurements in images taken in a variety of bands and in a variety of observing conditions, and even from multiple instruments.

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15/10 - 10:00 am BRT

Jeremy Tinker ( New York University )

The Red Sequence and How It Got That Way

I will focus on the growth of the red sequence from redshifts 1 to 0, using data from SDSS and COSMOS to isolate the different physical mechanisms that might quench a galaxy and cause it to migrate onto the red sequence. I will use the relationship between galaxies and dark matter halos to quantify the relative contribution to red sequence growth from field galaxies and group galaxies. I will demonstrate that, since z=1, the efficiency of quenching field galaxies is dramatically increasing, while the efficiency of quenching group galaxies is actually slowing down.

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01/10 - 11:00 am BRT

Sarah Kendrew ( Oxford University )

Integral field spectroscopy of high-redshift galaxies in the ELT era

High-resolution cosmological simulations are increasingly valuable for preparing surveys and studying the capabilities of future instrumentation. In combination with dedicated instrument simulators and astrophysical modelling methods, data from cosmological simulations can be transformed into realistic observations of a range of astrophysical targets. I’ll present the tools developed to produce observations of a RAMSES simulated star-forming galaxy at z=3 with the E-ELT first light integral field spectrograph HARMONI. Using the data, we investigate how well the properties of the star particle data, in particular the stellar kinematics, can be recovered from the simulated observations. In addition, by adjusting parameters in the instrumental simulation software, we use the simulation data to demonstrate how PSF convolution affects the ability to recover the galaxy’s properties, even for high-resolution adaptive optics-assisted observations. Finally, I’ll discuss future opportunities for extending the work to include more detailed physics, or to larger samples of galaxies.

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24/09 - 02:00 pm BRT

Zheng Zheng ( University of Utah )

Anisotropic Galaxy Clustering in the Isotropic Universe

Contemporary spectroscopic galaxy surveys (e.g., the Sloan Digital Sky Survey, or SDSS) can map out the distribution of galaxies in the universe in great detail. The clustering of galaxies measured from such surveys has become a powerful probe of cosmology and galaxy formation and evolution. I will talk about the anisotropic patterns seen in galaxy clustering and discuss what we can learn about cosmology and galaxy formation from such anisotropies. I will first talk about a gravitational origin of the anisotropic clustering, known as redshift-space distortion. I will highlight our recent work with SDSS/SDSS-III clustering data on studying the relation between galaxies and dark matter halos and on discovering the difference between galaxy and halo kinematics. Then I will move to a non-gravitational origin of the anisotropic clustering of high-redshift star-forming galaxies, a completely new effect predicted by our recent work from radiative transfer study of such galaxies. I will discuss the profound implications in using such galaxies to study cosmology and physical conditions and environments of galaxies and talk about the current observational status.

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17/09 - 10:00 am BRT

Adam Amara ( ETH Zürich )

Information from Cosmology Experiments and the Latest DES Results

Bayesian statistical methods have become common place in cosmology and numerous new experiments have reported posterior results on cosmological parameters. With all of these measurements we can ask basic questions such as: how much have given experiments contributed to our knowledge of the Universe? and are the results from different experiments consistent with each other? In this talk I will present a discussion of relative entropy and how this powerful statistical tool can be used to condense complex results to address these important questions. To demonstrate this tool I will present results from the CMB, before moving to the Dark Energy Survey, for which we have recently published our first cosmology results. In particular I will focus the last part of the talk on the challenges of making precision weak lensing measurements and the prospects for the upcoming data that we are processing now.

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10/09 - 10:00 am BRT

Rachel Mandelbaum ( Carnegie Mellon University )

Intrinsic galaxy alignments and the cosmic web

The intrinsic shapes of galaxies are not purely random, but rather exhibit coherent alignments (“intrinsic alignments”) with cosmological large-scale structure. Intrinsic alignments include a great deal of information about galaxy formation and evolution in a cosmological context, while also serving as a contaminant to weak gravitational lensing measurements (which assume that all coherent galaxy alignments are due to gravitational lensing). In this talk, I will discuss recent progress in our understanding of galaxy intrinsic alignments on both the observational side and the computational side, using SDSS-III BOSS data and SPH simulations, respectively. Recent work using massive BOSS galaxies has permitted a study of how galaxy intrinsic alignments vary from small scales (within massive halos) to cosmological scales, and how the level of the alignments scales with the galaxy environment (for brightest group galaxies, satellites in groups, and field galaxies). Among these new observational results is the fact that the level of small-scale alignments (<1 Mpc/h) correlates more tightly with the large-scale galaxy bias (from >10 Mpc/h) than with the galaxy luminosity. On the computational side, high-resolution SPH simulations with 100 Mpc/h box sizes are able to make predictions for how galaxy intrinsic alignments scale with galaxy properties, as well as to make verifiable predictions for the intrinsic alignment 2-point correlation functions of massive galaxies that are observed by existing galaxy redshift surveys. I will discuss challenges for using and interpreting simulated intrinsic alignment signals, and the latest results for their comparison with observations, as well as the implications for future weak lensing surveys.

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03/09 - 10:00 am BRT

Alex de Oliveira ( Observatório Nacional )

Pluto’s atmosphere from stellar occultations in 2012 and 2013

Pluto, as well as other objects of the Kuiper belt, is not very subject to the influence of solar radiation, so its atmosphere, provides information about the primordial composition of the protoplanetary cloud. As far as ground based observations are concern, the most effective technique to study Pluto’s atmosphere, is using stellar occultations lightcurves. In this work we present results from two Pluto stellar occultations observed on 18 July 2012 and 04 May 2013, and monitored respectively from five and six sites in South America. Both campaigns involved large telescopes (including the 8.2-m VLT at ESO/Paranal). The high SNR ratios and multi-chord coverage provide amoung the best Pluto atmospheric profiles ever obtained from the ground. We show that a spherically symmetric, clear (no-haze) and pure N2 atmosphere with a unique temperature profile satisfactorily fits the twelve lightcurves provided by the two events. We find, however, a small but significant increase of pressure of 6% (6-sigma level) between the two dates. We provide atmospheric constrains between 1190 km and 1450 km from Pluto’s center, and we determine the temperature profile with accuracy of a few km in vertical scale. This profile provides (assuming no troposphere) a Pluto surface radius of 1190 +/- 5 km, consistent with preliminary values obtained by New Horizons. Currently measured CO abundances are too low to explain an observed negative mesospheric thermal gradient. We explore the possibility of an HCN (recently detected by ALMA) cooling. This model, however, requires largely supersaturated HCN. Zonal winds and vertical compositional variations of the atmosphere are also unable to explain the observed mesospheric trend, leaving the question open. These events are the last useful ground-based occultations recorded before the 29 June 2015 occultation observed from Australia and New Zealand, and before the NASA’s New Horizons flyby of July 2015. This work can serve as a benchmark in the New Horizons context, enabling comparisons between ground-based and space results concerning Pluto’s atmospheric structure and temporal evolution.

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27/08 - 10:00 am BRT

Elmer Luque ( Universidade Federal do Rio Grande do Sul )

Search for substructure in the outer Milky-Way halo

The search for stellar substructures, such as globular clusters, dwarf galaxies and stellar streams, out to the farther fringes of our Galaxy helps us better understand the Milk-Way in many ways: the census of MW satellites and their remnants constrains models of structure formation, the process of mass accretion over time, the Galactic gravitational potential, and the structure and stellar populations of the Galactic Halo. We used a matched-filter technique applied to colour-magnitude data, originally developed by Balbinot et al (2011, MNRAS, 416, 393), to search for new stellar systems on the Dark Energy Survey (DES) first year data based on coadded images (Y1A1). Our goal has been the identification of new clusters and dwarf galaxies. The method was initially improved to be able to detect stellar substructure without prior knowledge of the generating population, using a grid of simulated CMD models instead. It was also validated with the Sloan Digital Sky Survey (SDSS), where we recovered most previously identified faint MW satellites. In this contribution we report on the new satellite candidates identified in the DES Y1A1 and Y2Q1 data. Additionally, we reported the discovery of a new star cluster using the first-year DES data. Finally, the SparSEx code detected new possible candidates for stellar objects in the Y2Q1 data, and the follow-up observations meant to confirm the physical reality of the sparser systems and to better constrain the properties of the richer ones.

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20/08 - 10:00 am BRT

Helio Perottoni ( OV UFRJ )

Mapping Triangulum-Andromeda with SDSS. Photometric Cartography

The Milky Way was formed in a complex chain of physical processes involving dissipative gravitational collapse, gas flows and galactic mergers. The outer stellar halo is home to a number of substructures that are likely remnants of former interactions of the Galaxy with its dwarf satellites. Triangulum-Andromeda (TriAnd) is one of these halo substructures, found as a debris cloud by Rocha-Pinto et al. (2004) using 2MASS M giants. We analyzed the region of Triangulum-Andromeda using photometric data from the Ninth Data Release of Sloan Digital Sky Survey (SDSS DR9). By comparing the observations with simulations from the TRILEGAL Galactic model we were able to identify and map several scattered overdensities of main sequence stars that seem to be associated with TriAnd over a large area covering ~ 500 deg2. At least two of these excesses may represent new, not previously known, stellar structures, and one of them resembles a faint stellar stream. Our estimates for the their luminosity and total stellar mass (~ 103 to 105 M_sun), for a population having [Fe/H] = -0.46 dex, 8 Gyr and a distance module of 16.3 mag, are compatible with other halo overdensities and with the luminosity of some ultra-faint Milky Way satellites.

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13/08 - 10:00 am BRT

Kyoung-Soo Lee ( Purdue University )

Probing the Early Epoch of Massive Cluster Formation

Galaxy clusters serve as unique laboratories to study galaxy formation and cosmology. Nevertheless, little is known about the early stage of cluster formation when the cluster members assembled the bulk of their masses. Long before these galaxies are observed, they shut down star formation and evolved passively since. While this general picture is accepted, the detailed star formation histories of typical cluster galaxies, when/how they shut down star formation, and how these differ from those of field galaxies are not well understood. The biggest challenge has been to identify the sites of massive cluster progenitors (or ‘protoclusters’) at the peak epoch of their formation (z>~3) as such efforts require sampling of very large volumes and adequate imaging/spectroscopy sensitivities to unambiguously determine protocluster membership. Based on the existing data on the recently discovered massive protocluster (total mass >~10^15 Msun, similar to that of the Coma), I will present several observational evidence that suggest that a systematic search for massive protoclusters can be conducted efficiently utilizing several characteristics that mark the protocluster sites and their constituents. Preliminary results on the properties of several confirmed protoclusters, compared to the field, will be discussed.

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30/07 - 02:00 pm BRT

Francisco Förster Burón ( Universidad de Chile )

The High cadence Transient Survey (HiTS): real-time detection of supernovae and other transients with DECam

At the Astroinformatics Laboratory of the Center for Mathematical Modelling (CMM) at the University of Chile and the Millennium Institute for Astronomy (MAS) we have developed a novel transient detection pipeline to be used in real-time with data from the Dark Energy Camera (DECam). DECam is a 520 Megapixel CCD camera with an unprecedented wide angle field of view mounted on the 4m Blanco telescope at the Cerro Tololo Inter-American Observatory (CTIO). During 5/6 contiguous nights in the 2014/2015 we were able to achieve the real-time data analysis of more than 120/150 square degrees of the sky with a cadence of only 2/1.6 hours. We processed more than 1000 billion pixels in total, leading to the discovery of 30/90 new SNe. We also found thousands of previously unknown asteroids and hundreds of variable stars that can be used to map the structure of the outer parts of the Milky Way.

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16/07 - 10:00 am BRT

Tim Eifler ( Jet Propulsion Laboratory )

CosmoLike – Preparing for multi-probe cosmological likelihood analyses with Dark Energy Survey data

The Dark Energy Survey (DES) has recently completed its second season of observations, now covering the full 5000deg^2 survey footprint at varying depth (23.2-23.4 mag in the i-band). This high quality data set will be extended to a depth of 24 mag i-band during the next 3 years but already today it poses new challenges for the precise modeling of observables of the Universe’s Large-Scale Structure (LSS), and its astrophysical and observational systematics. The tightest constraints on cosmology from DES data will be obtained through a joint analysis of all probes (e.g., weak lensing, galaxy clustering, magnification, cluster masses). Such joint analyses face several difficulties: First, the cosmological information is highly correlated, which requires a joint likelihood including all cross correlations between the individual probes. Second, even more problematic are the correlations of various systematic effects originating from astrophysics and the measurements themselves. In this talk I will give a quick introduction to the DES collaboration and survey. I will then describe the CosmoLike analysis framework that is being developed for a joint likelihood analysis of multiple cosmological probes extracted from DES data. This multi-probe DES analysis is an excellent starting point to prepare for challenges of future data sets from LSST, Euclid, and WFIRST.

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09/07 - 10:00 am BRT

Gary Bernstein ( University of Pennsylvania )

How clear is a cloudless sky?

Every astronomy student learns how to make photometric measurements with array-camera data by using a flat-field and standard stars. The Sloan and PanStarrs surveys have estimated photometric errors of ~0.01 mag, achieved by a renewed emphasis on using internal consistency to build more accurate models of the instrument response. What physical effects are not properly treated by the standard calibration methods? I’ll show how millimag repeatability is attainable on a given night of DES observations with careful treatments of CCD nonlinearities, pixel-size variations, varying spectral response, and scattered light, that are not part of typical image processing. To tie together all the DES data at millimag level, we have to ask some basic questions: how much does the transparency of the sky vary over time and space on cloudless “photometric” nights? How much does the instrument response change over months or years? I’ll present encouraging results of studies with DES.

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25/06 - 10:00 am BRT

Henry McCracken ( Institut d’Astrophysique de Paris )

Galaxies, dark matter haloes and how efficiently galaxies form: new results from the UltraVISTA survey

In my talk I will present the UltraVISTA survey, an ultra-deep near-infrared survey of the COSMOS field. By combining this data with broad-band and medium-band photometry from Subaru telescope and the Spitzer space telescope, together with a very large number of spectroscopic redshifts, we are able to derive precise photometric redshifts and stellar masses for a very large sample of galaxies in the redshift range 0 < z < 2. We will use this mass-selected sample to investigate the relationship between galaxies and the dark matter haloes which host them over more than half of the age of the universe. We discuss the implications this work has for how efficiently galaxies form stars and what is the fate of satellites galaxies in dark matter haloes. Finally, I will briefly describe the prospects for continuing this study with the latest UltraVISTA / COSMOS data sets which will be publicly available before the end of the year.

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11/06 - 11:00 am BRT

Flavia Sobreira ( Fermi National Accelerator Laboratory )

DES Large Scale Structure First Results

In this talk I will present results of galaxy clustering selected from the photometric Science Verification data of the Dark Energy Survey. The SV data corresponds to a period of observations in late 2012 and early 2013 that provided science-quality images for more than 250 sq. deg. at the nominal depth of the survey (iAB ∼ 24). I will put particular emphasis in detailing how we mitigate systematic effects that comes from potential sources as seeing, airmass, sky brightness and also about the behavior of galaxy bias over a broad range of linear scales and its comparison with a CFHTLS sample, showing that the results from both galaxy samples are in very good agreement.

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28/05 - 10:00 am BRT

Dante Miniti ( UNAB/MAS/CATA Chile )

Rediscovering the Milky Way with the VVV Survey

As one of the major surveys of the southern sky, the VISTA telescope at ESO’s Paranal Observatory in Chile is mapping the central regions of the Milky Way in infrared light to search for new and hidden objects. The VVV survey (standing for VISTA Variables in the Via Lactea) returns to the same parts of the sky again and again to spot objects that vary in brightness as time passes. By observing in infrared light, astronomers can see right through the dust-filled central parts of the Milky Way and spot many previously hidden objects. In just this tiny part of one of the VISTA surveys, astronomers have discovered two unknown and very distant Cepheid variable stars. They are the first such stars found that lie in the central plane of the Milky Way beyond its central bulge.

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21/05 - 10:00 am BRT

Emmanuel Bertin ( Institut d’Astrophysique de Paris )

The DANCe project: recycling 15 years of archival wide-field data for kinematic studies

The DANCe (Dynamical Analysis of Nearby ClustErs) project aims at deriving a comprehensive census of the stellar and substellar content of a number of nearby (1 kpc) young (500 Myr) associations. Members are identified based on their kinematics properties, ensuring little contamination from background and foreground sources. I will show how robust individual proper motions can be computed with a precision better than 1 mas/yr by combining thousands of wide-field images downloaded from public archives and covering more than a decade of observations. I will present the first results of the survey and discuss the technical challenges associated with the use of large wide-field image datasets from existing public archives.

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28/04 - 02:00 pm BRT

Paolo Giommi ( ASDC )

The ASI Science Data Center: Scientific results and technical activities

The ASI Science Data Center (ASDC) is a facility of the Italian Space Agency dedicated to the acquisition, processing, archival and distribution of scientific data from several scientific satellites, 13 of which are currently operational. It operates in the fields of astrophysics, cosmology, solar system exploration, and cosmic-rays. A general overview of the ASDC will be presented together with the description of some on-going activities aimed at establishing a similar facility in Brazil, in cooperation with several Brazilian institutions. Some of the most relevant scientific results, mostly in extragalactic astrophysics will also be presented.

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16/04 - 10:00 am BRT

Gail Zasowski ( JHU )

New Tools for Galactic Archeology from the Milky Way

One of the critical components for understanding galaxy evolution is understanding the Milky Way Galaxy itself — its detailed structure and chemodynamical properties, as well as fundamental stellar physics, which we can only study in great detail locally. This field is currently undergoing a dramatic expansion to the kinds of large-scale statistical analyses long used by the extragalactic community, among others, thanks in part to the enormous influx of data from multiple large space- and ground-based surveys. I will describe the Milky Way and Local Group in the context of general galaxy evolution and highlight some recent developments in Galactic astrophysics that have strong implications for our understanding of how galaxies form and change across cosmic time. These advances include work done to characterize different elusive phases of the ISM, to describe the resolved bulk stellar properties of the inner disk and bulge, and to map stellar chemical properties and star formation histories throughout the Galactic disk. The rapid progress in these areas promises to continue, with the advent of coming datasets from missions like APOGEE, Gaia, and WFIRST.

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09/04 - 11:00 am BRT

David Nidever Nidever ( University of Michigan )

Examining Galaxy Formation and Evolution with the Milky Way and Its Satellites

How galaxies form and evolve remains one of the cornerstone questions in our understanding of the universe on grand scales. The Milky Way and its satellites are a local laboratory for studying the evolution and properties of galaxies of various masses in great detail. I will highlight some recent results from several projects that are providing new insights into the structure and formation history of the Milky Way and the Magellanic Clouds. First, I will discuss some of my work with the SDSS-III/APOGEE data including a recent result that suggests that the early evolution of the MW disk was characterized by stars that shared a similar star formation history and were formed in a well-mixed, turbulent, and molecular-dominated ISM with a short gas consumption timescale. Second, my investigation of the gaseous Magellanic Stream has found that stellar feedback is an important mechanism in its formation and that the Stream is significantly longer than previously thought which has important implications for the interaction history of the MCs with each other and the MW. Finally, in an effort to observationally constrain stellar structure formation on small scales, I have undertaken a multi-faceted photometric and spectroscopic study of the Magellanic Clouds. I will discuss various results from this work including the discovery of remarkably extended stellar components of both the LMC and SMC, reaching distances of ~20 kpc and ~10 kpc from their respective centers. I will also discuss some initial results from SMASH (Survey of the Magellanic Stellar Periphery), a new NOAO community DECam survey that is photometrically mapping the stellar periphery of the Magellanic Clouds for low surface brightness features.

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26/03 - 10:00 am BRT

Carlos Frenk ( Durham University )

Cosmology in our Backyard

One of the most impressive advances in Physics in the past three decades is the development of the “standard model of cosmology,” LCDM (where L stands for Einstein’s cosmological constant and CDM for cold dark matter). This model accounts for an impressive array of data on the structure of the Universe on large-scale scales, from a few gigaparsecs down to a few megaparsecs. On the scales of galaxies and clusters, however, the model cannot be tested with the same degree of rigour as on larger scales where microwave background radiation data and measures of galaxy clustering provide clean and well-understood diagnostics. Yet, it is precisely on these small scales that the nature of the dark matter manifests itself most clearly. I will discuss theoretical predictions for the small-scale structure of the universe which appear to be discrepant with recent kinematical data for satellite galaxies of the Milky Way. Possible solutions range from the relatively mundane – that the mass of our galaxy is smaller than is often thought – through exotic baryonic processes to the more radical assumption that the dark matter is not what the standard model assumes.

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19/03 - 10:30 am BRT

Bob Nichol ( University of Portsmouth )

Dark Energy Survey Supernova Survey

The Dark Energy Survey (DES) has just completed its second of five years of observations. A key part of DES is a new search for high redshift supernovae; the biggest search for such events ever undertaken. In this talk, I will review DES focusing on this new supernova survey and outline the techniques we are employing to find and classify thousands of supernova-like transient events. In addition to “normal” supernovae, DES has also found a number of interesting transient, especially several examples of a new breed of “superluminous supernovae”. I will discuss these new cosmic explosions and present examples now detected in DES to z>1. I will finish by looking forward to LSST which could find thousands such supernovae.

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05/03 - 10:00 am BRT

Richard McMahon ( University of Cambridge )

Quasars in formation and in the Epoch of Reionization

Sensitive new near infra-red surveys with the VISTA telescope in Chile are allowing us to probe two significant epochs of galaxy and super massive black hole formation; the peak of galaxy and supermassive black hole activity at a redshifts of around 2-3 and the epoch of the first galaxies and supermassive black holes at redshifts above 6. I will review the current status of near IR surveys in the Southern Hemisphere with a focus on the near IR VISTA surveys and the complementary new optical surveys with the VST and the Dark Energy Survey. I will also present recent results from our surveys for z>6 quasars focusing on the new results at z>6.5 including the recent detection of 158micron [CII] cooling line with IRAM and ALMA and the properties of the intergalactic medium at high redsdshift. I will summarise the current status of these surveys and highlight recent scientific results and prospects for the next 3-5 years.

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12/02 - 10:00 am BRT

Alessandro Morbidelli ( Observatoire de la Côte d’Azur )

Solar System formation and evolution

The discovery of over 1,000 extrasolar planets reveals a huge diversity of planetary system architectures, even when restricting the sample to the sole giant planets. We see many Jovian planets at distances from the parent stars comparable to those of our terrestrial planets or even much smaller (hot Jupiters), as well as on orbits with a variety of eccentricities, ranging up to almost unity. These wild and surprising orbits are usually explained invoking two processes: planet migration and planet instabilities. Then, the question arises on whether our Solar System experienced these processes as well and why its structure looks so different from those of the giant planet extrasolar systems discovered so far. Luckily, we have a huge number of observational constraints that can guide us to reconstruct with some confidence the evolution of the Solar System back to the time of giant planet formation. A non-exhaustive list of constraints is made of: the orbits of the giant planets (non-resonant, partially eccentric and inclined), the Earth/Mars dichotomy (mass ratio, formation timescales), the asteroid belt (depleted, excited, featuring 2 distinct populations partially mixed, accretion within 3My, less than 10Gy-equivalent collisional evolution), Jupiter’s Trojans (extremely strong dynamical excitation, L4/L5 asymmetry), the irregular satellites populations (similar for all giant planets once rescaled to the planet’s Hill radius), the Kuiper belt (complex structure with cold, hot, resonant and scattered populations), the Oort cloud (its large population, compared to the Kuiper belt), the Late Heavy Bombardment of the Moon. I will present a model that can explain the global structure of the Solar System, consistent with all constraints listed above. If this model is correct, it suggests that the specific structure of the Solar System is due to some specific and fortuitous events that happened during its evolution. Changing slightly these events produces, through a chaotic propagation of effects, radically different final systems which cover a wide portion of the observed diversity of planetary systems.

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05/02 - 04:00 pm BRT

Eric Bellm ( Caltech )

The Dynamic Universe

The advent of wide-field synoptic imaging has re-invigorated the venerable field of time domain astronomy. We begin with various science results from the ongoing Palomar Transient Factory (PTF) survey — newborn supernovae, gap transients, orphan afterglows, relativistic explosions and near earth asteroids. Our next-generation survey, the Zwicky Transient Facility (ZTF), provides more than an order of magnitude improvement in survey speed. We describe its design, science goals, and public surveys. Mansi Kasliwal (Carnegie Observatories) Eric Bellm (Caltech)

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29/01 - 10:00 am BRT

Christopher Bonnet ( Institut de Fisica d’Altes Energies )

Machine learning for photometric redshifts

I will be discussing the current state of machine learning for photometric redshifts from a machine learning standpoint and a astronomy standpoint. This include usage of algorithms, PDF estimation and handling of the photometric errors. I will give an overview of the current status in the DES. I will talk about the pitfalls that we face and the problems we will have to solve if we are wanting to perform precision cosmology with 5-year DES data (or LSST, Euclid).

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22/01 - 12:00 pm BRT

François Mignard ( Observatoire de la Côte d’Azur )

The GAIA mission: objectives, principle, status

A year ago ESA successfully launched the Gaia satellite to survey our Galaxy with astrometry, photometry and spectroscopy. The main goal is to investigate the formation and evolution of the Milky Way through the kinematics and physics of its stars. Astrometry will give the position, proper motion and distances to an unprecedented accuracy down a 20 mag for about 1 billion sources. I will explain how the instruments on-board can achieve this ambitious goal with a scanning satellite and will report on the actual performances as seen after the commissioning phase. Some early achievement will be shown as well to support the claim that Gaia will be a success despite some unexpected hardware problems detected in the early weeks of the mission.

2014 35

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11/12 - 10:00 am BRT

Luiz Nicolaci da Costa ( ON/LIneA )

Reviewing 2014 and Outlook for 2015

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27/11 - 10:00 am BRT

Hendrik Hildebrandt ( Bonn University )

PHAT: PHoto-z Accuracy Testing

Photometric redshifts (photo-z) have become a major tool in extragalactic astronomy used to add a third dimension to the inherently two-dimensional images of the sky. Being easier to obtain and going deeper than spectroscopic redshifts photo-z are indispensable in situations where approximate distances to large numbers of faint galaxies are needed (e.g. weak gravitational lensing). Testing and characterising the accuracy of photo-z is an important ingredient in making current and future imaging surveys reach their scientific goals. In PHAT (PHoto-z Accuracy Testing) we established blind test environments to test one crucial ingredient influencing the accuracy of photo-z in isolation, the photo-z algorithm/method. Results are presented showing the convergence of different algorithms which suggests that a theoretical limit has been reached by the most mature algorithms. Still several areas where significant improvement can be achieved (beyond the pure algorithm) are highlighted. More recent developments are presented and the most pressing problems are discussed with a special emphasis on issues related to future weak lensing projects to study the nature of the accelerating expansion of the Universe.

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13/11 - 01:30 pm BRT

David Gerdes ( University of Michigan )

Characterizing the trans-Neptunian Solar System with DES

The population of solar system objects beyond Neptune preseves a fossil record of events that shaped the solar system. Members of the Kuiper Belt turn out to have a rich dynamical structure that includes a classical disk, objects in mean motion resonances with Neptune, scattered disk objects, and even a handful of detached/inner Oort Cloud objects which cannot have been placed into their orbits through interactions with the major planets in their current configuration. With an unprecedented combination of area and depth, the Dark Energy Survey is well-positioned to discover hundreds of new trans-Neptunian objects and elucidate the history that produced this complex structure. I will describe a search for TNOs in the DES supernova fields and discuss the properties of the objects that have been discovered to date. I will also discuss the challenges and benefits of extending the search to the full DES survey area.

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07/11 - 12:00 am BRT

Stephane Arnouts ( Laboratoire d’Astrophysique de Marseille )

The UV side of galaxy evolution

During the last decade a clear picture has emerged about the evolution of SFR and Stellar Mass densities from 0: the SF activity peaks at z~1-2, followed by a drop of a factor ~10-20 up to now. Exploring the evolution of the galaxy properties with cosmic time and environment is one approach to understand the physical processes that regulate the star formation activity. To this end a wealth of multi-wavelength surveys have been used with a variety of SF indicators (UV/Ha/OII/FarIR/radio/..). Among them, UV is of particular interest since it is available over the entire redshift range. Although it is severely affected by dust, if this issue can be solved, then UV offers a unique opportunity to explore the low mass world (10^8 in contrast to other estimators like the Far-IR or optically selected surveys dominated by massive galaxies. This is interesting since the Star Formation Efficiency is thought to be a balance between gas accretion and feedback processes which may differ on both side of the mass function knee (M~10^10.3 Mo). In this talk, I will first revisit our original GALEX luminosity functions based on a new photometric algorithm developed for GALEX images. By using the Far-Infrared observations in the COSMOS field, I will present a new method to predict the dust amount (or infrared excess, IRX=Lir/Luv) in galaxies based on a single color vector combining NUV, r, K luminosities (which can be of interest for future optical/NIR surveys). With this in hand, I will explore the evolution of the SFR Density up to z=1.5, the relative contribution of low and massive galaxies, and its implication on the general framework of galaxy formation.

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06/11 - 12:00 am BRT

Ben Burningham ( University of Hertfordshire/NASA Ames )

Testing substellar atmospheric models with benchmark brown dwarfs

The current generation of wide field surveys are probing such a volume that significant numbers of brown dwarfs are being identified as rare wide common proper motion binary companions to higher mass stellar primaries. If such systems are formed in the same manner as similarly separated stellar binaries then it follows that the composition and age of the primary may be used to infer the same properties for the low-mass companion, making such systems crucial calibrators of exoplanetary and substellar atmospheric model grids. They are thus referred to as benchmark systems. I will discuss the current status of the substellar benchmark sample, highlighting how the emerging grid of calibrated atmospheres can be used to provide new insights into the strengths and deficiencies of differing model approaches. Finally, I will examine how the potential of benchmark brown dwarfs for breaking observational degeneracies can be realised to solve key science goals in exoplanetary science.

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30/10 - 10:00 am BRT

Beth Willman ( Havefroth College )

Observational cosmology in the Milky Way’s backyard

The ultra-faint dwarf galaxies discovered around the Milky Way and M31 over the last decade includes objects with less than one millionth of the Milky Way’s own luminosity. The detailed properties of these puny satellites, as well as the remnants thereof, are being used to test dark matter+galaxy formation models. To fully exploit the Milky Way’s halo to test such models requires a stellar halo map that is as complete and unbiased as possible. I will discuss how wide-field surveys will contribute to mapping the Milky Way out to its virial radius. I will focus on efforts to learn about ultra-faint dwarf galaxies and their relationship with dark matter halos, and early results from a program to map the Milky Way to its outermost regions using M giant stars.

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09/10 - 11:00 am BRT

Jeffrey Kantor ( LSST )

Future Wide Field Imaging with LSST

The Large Synoptic Survey Telescope (LSST) project is a proposed large-aperture, wide-field, ground-based telescope that will survey half the sky every few nights in six optical bands. LSST will produce a data set suitable for answering a wide range of pressing questions in astrophysics, cosmology, and fundamental physics. The 8.4-meter telescope will be located in the Andes mountains near La Serena, Chile. The 3.2 Gpixel camera will take 6.4 GB images every 15 seconds, resulting in 15 TB of new raw image data per night. An estimated 10 million transient alerts per night will be generated within 60 seconds of when the camera’s shutter closes. Processing such a large volume of data, converting the raw images into a faithful representation of the universe, automated data quality assessment, automated discovery of moving or transient sources, and archiving the results in useful form for a broad community of users is a major challenge. We present an overview of the planned computing and network infrastructure, database architecture, and pipelines for LSST, and highlight challenges in each area.

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02/10 - 10:00 am BRT

Maria Teresa Crosta ( Observatorio Astrofisico di Torino )

Gravitational Astrometry in the Gaia Era

Advancements in astronomical observations and technical instrumentation requires coding light propagation at high level of precision. Indeed light propagation and its subsequent detection should be conceived in a fully relativistic context, whenever the accuracy of the measurements are comparable to the curvature due to the gravity source background geometry. This is particularly needed for the Gaia space missions (ESA), launched on December 2013, whose main goal is to trace back star directions from within our local curved dynamical Solar System. By achieving the μ-as accuracy, Gaia will not only greatly enhance our knowledge of the Galactic structure, but it will also provide precise information allowing astronomers to frame a much more detailed kinematical picture of our Galaxy than what presently available. A 6-dimensional accurate reconstruction of the individual stars across a large portion of the Milky Way necessarily needs rigorous relativistic modeling of Gaia observables consistently with the precepts of General Relativity (GR) and the theory of measurements; the relativistic consistency of the whole data processing chain, together with an appropriate realization of the reference frames, are indispensable prerequisites for having the physical correct determination of distances, parallaxes and proper motions. Moreover, Gaia, repeatedly observing over 5 years a million or so of bright and stable stars, will constitute by far the largest and most thorough astronomical experiment in testing GR ever attempted, possibly with the sensitivity for testing the dilaton-runaway scenario. In the form of repeated Eddington-like differential experiments the detection of the light deflection due to Jupiter’s quadrupole, predicted by GR and yet to be proved, will be performed. It seems that, with such an unprecedented novelty of forthcoming data, fundamental astronomy cannot be set aside from fundamental physics, and astrometry will become even more intimate with probing cosmology at zero redshift, dealing with local cosmology, where accurate absolute motions of stars within our Galaxy will provide access to the cosmological signatures left in the disk and halo.

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25/09 - 02:00 pm BRT

Eduardo Rozo ( Stanford )

Planck Clusters and Neutrino Mass

The Planck collaboration found that the abundance of galaxy clusters as measured with Planck appears to be in tension with CMB data, unless one allows for massive neutrinos. We will critically review the evidence for neutrino mass from Planck galaxy clusters, connecting it to the well known Planck—maxBCG discrepancy.

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18/09 - 11:00 am BRT

Michael Strauss ( Princeton University )

The Evolution of Quasars with Cosmic Time

While the luminosity and mass distributions of quasars has evolved dramatically with cosmic time, the physical properties of quasars of a given luminosity are remarkably independent of redshift. I will describe recent results on the spectra of luminous quasars, the dark matter halos in which they sit, and the intergalactic medium of their host galaxies, that are essentially indistinguishable from moderate redshifts to z>6. The one property apparently unique to the highest-redshift quasars is that some small fraction show evidence for having very little infrared excess from hot dust. Dust obscuration is another theme in quasar studies; an appreciable fraction of the growth of black holes may be hidden at optical wavelengths by dust. I will describe searches for obscured quasars at high redshift and low, and studies of their demographics and physical properties. I will also describe recent results on the properties of the host galaxies of quasars.

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11/09 - 10:00 am BRT

Stefano Borgani ( OATS/INAF )

Cosmology with galaxy clusters: the role of simulations

In my talk I will first briefly review the application of galaxy clusters as tools to trace cosmic evolution. I will then discuss the recent advances in the this field, as driven by the increasing quality of observational data, and by the much improved description of clusters through detailed numerical simulations. I will present recent results on the analysis of such simulations aimed at calibrating clusters as precision tools for cosmology. In this context, I will discuss (a) possible biases that affect mass estimates based on X-ray and weak lensing data; (b) effects of baryons on the calibration of the halo mass function. I will finally discuss the perspectives for precision cosmology with galaxy clusters offered by the future generation of large multi-wavelegth surveys.

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04/09 - 02:00 pm BRT

Enrique Gaztañaga ( IEEC-CSIC )

LSS with angular cross-correlations:Combining Spectroscopic and Photometric Surveys

The search for the nature of the dark sector relies on the combination of multiple techniques and probes, from both spectroscopic and photometric data. This matches well with the fact that some probes are intrinsically 3D (like RSD) and some 2D (like WL). But to get the best constraints we need to combine all of these.We show how using angular cross-correlations we can recover the full 3D galaxy clustering information, including BAO and RSD in spectroscopic surveys. This allows the combination of spectroscopic and photometric galaxy surveys, including photo-z error calibration and addition of WL. We show some application of these ideas in current data and simulations and show how overlapping surveys result in both better constrains and better understanding of systematic errors.

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28/08 - 11:00 am BRT

Basilio Santiago ( UFRGS )

Resolved Stellar Populations: DES and beyond

In the Cold Dark Matter (CDM) structure formation scenarios, the mass assembly process of a large spiral galaxy like our own is expected to have involved many smaller and dark matter rich fragments with masses comparable to the currently observed dSph and dE galaxies. These are in fact the most abundant galaxies in the Universe. The currently known population of such systems around the Galaxy has doubled in recent years, with most of the recent discoveries coming from the analysis of SDSS data. Yet, a much larger number of Galactic satellites is expected from CDM simulations of a MW-like galaxy, and this large discrepancy is called the missing satellite problem. Many stellar streams have also been detected recently, attesting that the mass accretion process is an on going one. All this has led to a new picture of the MW halo as a stellar component full of substructure from which the DM content and gravitational potential of the Galaxy can be modelled and structure formation scenarios can be tested. DES is the next large survey capable of uncovering a large number of new MW satellites, both dwarf galaxies and star clusters, as well as their stellar left overs. In this talk I will give an overlook of on going and future research based on DES stellar data, with an emphasis on the search for and characterization of newly found stellar systems around the Galaxy. Time allowing, I will also mention some other perspectives opened up by other large spectroscopic and photometric surveys, both in the present and future, such as SDSS-III, SDSS-IV, GAIA, and LSST, for better understanding MW structure and stellar populations.

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21/08 - 11:00 am BRT

Jo Bovy ( Princeton University )

Unraveling the Milky Way’s history with APOGEE

Observations of the structure and dynamics of different stellar populations in the Milky Way provide a unique perspective on galaxy formation, evolution, and dynamics. APOGEE is at the forefront of a new generation of surveys probing the chemo-dynamical structure of the Milky Way over large volumes in the disk and halo. I will discuss key science results from APOGEE-1.

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14/08 - 11:00 am BRT

Luciano Nicastro ( INAF – IASF Bologna )

Databases and web technologies for astronomy

We live in the Web 2.0 era. And the next level is approaching.The question is: does astronomy take advantages of these innovative, modern web technologies? I would say it doesn’t. We know that astronomers, and scientists in general, are very resilient to changes of habits. The reasons for that are several and partially understandable. However I’ll try to demonstrate that a modern approach to astronomical data management, visualization and analysis is not just a matter of aesthetic. Database management systems, relational and NoSQL, are becoming an accepted tool in astronomy. But the peculiarity of the astronomical data may reduce their performance and usability. However understanding well the problem is a good starting point to solve it. As a use case example, I’ll show how the spherical data management was solved in MySQL, the most used open source DBMS. Web technologies are very suitable to develop user friendly web-based tools for observational astronomy and can boost the exploitation of huge data archives such as those that will be produced by ground and space projects, like LSST, GAIA, TAOS-II, etc. But it would also be much easier to manage heterogeneous or multi-wavelength data. In spite these technologies, e.g. HTML5, WebSocket, WebGL, WebCL, WebRTC (note the “Web” prefix) are still not fully mature, they are already accepted and “open” standards in the browsers of our laptops, tablets and cellphones. To use web-tools, nothing but an updated browser is required to the user. Nothing to install or to maintain, i.e. no Apps, no OS incompatibility, … no Java!I’ll discuss the impact of these new technologies in astronomy and present examples to show their capabilities.

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07/08 - 02:00 pm BRT

Jeff Newman ( University of Pittsburgh )

Exploring the Milky Way and the Universe with Extragalactic Surveys

Determining the global properties of the Milky Way presents unique challenges, primarily due to our position embedded within its disk. As a result our knowledge of many basic properties of the Galaxy, including its color and luminosity, has remained limited. In this talk, I will describe how we have developed improved determinations of the total stellar mass (M) and star formation rate (SFR) of the Milky Way using Hierarchical Bayesian statistical techniques. We then use the results, in combination with data from SDSS, to better determine the Galaxy’s luminosity and integrated color. We exploit the close relationship between galaxies’ photometric properties and their total stellar mass and star formation rate. We thus select a sample of Milky Way analog galaxies designed to match the best Galactic M and SFR measurements, including measurement uncertainties. Applying the Copernican assumption that the Milky Way should not be special amongst galaxies of similar properties, the color and luminosity distribution of these Galactic analogs then constrains the properties of our own Galaxy much more tightly than previous measurements. In the remaining time, I will describe the next steps in large spectroscopic surveys of the distant universe. I will provide an overview of the eBOSS project, a component of the next-generation SDSS-IV survey beginning observations this summer; eBOSS will obtain redshifts of ~650,000 galaxies and ~850,000 QSOs at 0.6 < z < 3.5 in order to study dark energy via the Baryon Acoustic Oscillations (BAO) technique. I will also describe plans for DESI, the Dark Energy Spectroscopic Instrument, which may be used for a survey of >20 million galaxies and QSOs, placing strong constraints on dark energy models via BAO early in the next decade.

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31/07 - 11:00 am BRT

Boris Leistedt ( UCL )

Constraints on Primordial non-Gaussianity from 800,000 photometric quasars

I will present robust constraints on primordial non-Gaussianity from the clustering of one million photometric quasars from the Sloan Digital Sky Survey (SDSS). The constraints on $f{\\rm NL}$, its spectral index, and $g{\\rm NL}$, are the tightest ever obtained from a single population of quasars or galaxies, and are competitive with the results obtained with WMAP, demonstrating the potential of quasars to probe the largest scales of the universe and complement CMB experiments. These results take advantage of a novel technique, ‘extended mode projection’, to mitigate the complex spatially-varying systematics present in the survey in a blind and robust fashion. This approach is promising for exploiting the full potential of the Dark Energy Survey, Euclid and LSST, which require a careful mitigation of systematics in order to robustly constrain new physics.

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24/07 - 11:00 am BRT

Jim Annis ( Fermilab )

The DES and gravity wave counterpart detections

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26/06 - 11:00 am BRT

Mario Mateo ( University of Michighan )

The Present and Future(?) of Multi-Object Fiber Spectroscopy

THe Michigan/Magellan Fiber System (M2FS) has recently begun operation at the Magellan/Clay telescope. I describe the key feature of M2FS and summarize some early science that has come out of the instrument. I also summarize some of the novel features of M2FS that make it a potentially powerful basis for a large-scale spectroscopic survey facility.

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05/06 - 11:00 am BRT

Felipe Braga Ribas ( Observatório Nacional )

A ring system detected around the Centaur (10199) Chariklo – Parte II

The Milky Way ultra-faint galaxies are the least luminous and most dark matter dominated galaxies in the known Universe. We have recently shown that these galaxies are also the oldest known galaxies, containing exclusively old stars (>11 Gyr). We have also shown that the Milky Way ultra-faint dwarf galaxies have shallower IMF slopes as compared to the Milky Way over the mass range 0.5 – 0.75 M_sun. I will review both of these results and their implications for galaxy formation at all mass scales.

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29/05 - 02:00 pm BRT

Steven Kahn ( Standford University )

LSST science overview

The Large Synoptic Survey Telescope is a large-aperture, wide-field, ground-based telescope designed to survey the entire southern sky every few nights in six optical color bands. As such it will enable a diverse array of scientific investigations ranging from studies of moving objects in the solar system to the structure and evolution of the universe as a whole. The project has recently been approved for construction as a joint effort between the National Science Foundation and the Department of Energy in the United States. I will review the basics of the LSST system design and highlight a selection of the exciting science topics that LSST will address.

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08/05 - 11:00 am BRT

Matias Carrasco Kind ( UIUC )

How to produce, combine, store and use photo-z PDFs

As we enter the era of precision cosmology, there has been a widespread adoption of photometric redshift probability density functions (PDFs) to aid in cosmological measurements as these provide much more information than single redshift estimates that allows, among other advantages, tighter constrains. On one hand, both current and future photometric surveys like DES or LSST are expected to obtain images from millions to billions of distinct galaxies, therefore the computation of these photo-z PDFs as well as their storage and management is becoming a increasingly important challenge. On the other hand, currently there exist a very wide variety of algorithms to compute these photo-z’s, each with their own strengths and weaknesses. In this talk I will discuss how tools from Machine Learning and Statistics can help us to address these issues by reviewing our work on the computation, efficient Bayesian combination, highly compressed storage and application of photo-z PDFs which will help us to better understand the dark components of the universe.

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24/04 - 10:00 am BRT

Marla Geha ( Yale University )

The Baryon Content of Ultra-Faint Galaxies

The Milky Way ultra-faint galaxies are the least luminous and most dark matter dominated galaxies in the known Universe. We have recently shown that these galaxies are also the oldest known galaxies, containing exclusively old stars (>11 Gyr). We have also shown that the Milky Way ultra-faint dwarf galaxies have shallower IMF slopes as compared to the Milky Way over the mass range 0.5 – 0.75 M_sun. I will review both of these results and their implications for galaxy formation at all mass scales.

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17/04 - 10:00 am BRT

Jim Rich ( SPP – Saclay )

Dimensional Analysis in Cosmology

Dimensional analysis plays an important background role in physics, allowing us to understand much without doing much. It highlights the roles of fundamental constants and demonstrates, ironically, that only the dimensionless constants are really fundamental. In this presentation, I will dimensionally analyze a variety of cosmological measurements with the hope gaining some insight into the measurements of cosmological parameters and the limits that those measurements place on time-variations of fundamental constants.

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10/04 - 10:00 am BRT

Felipe Braga Ribas ( Observatório Nacional )

A ring system detected around the Centaur (10199) Chariklo – Parte I

Hitherto, rings have been found exclusively around the four giant planets in the Solar System. Rings are natural laboratories in which to study dynamical processes analogous to those that take place during the formation of planetary systems and galaxies. Their presence also tells us about the origin and evolution of the body they encircle. Here we report observations of a multichord stellar occultation that revealed the presence of a ring system around (10199) Chariklo, which is a Centaur–that is, one of a class of small objects orbiting primarily between Jupiter and Neptune–with an equivalent radius of 124 + 9 kilometres. There are two dense rings, with respective widths of about 7 and 3 kilometres, optical depths of 0.4 and 0.06, and orbital radii of 391 and 405 kilometres. The present orientation of the ring is consistent with an edge-on geometry in 2008, which provides a simple explanation for the dimming of the Chariklo system between 1997 and 2008, and for the gradual disappearance of ice and other absorption features in its spectrum over the same period. This implies that the rings are partly composed of water ice. They may be the remnants of a debris disk, possibly confined by embedded, kilometre-sized satellites.

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03/04 - 12:00 pm BRT

Mario Juric ( LSST )

LSST Data Management: Overview of the System

The Large Synoptic Survey Telescope (LSST) is a planned, large-aperture, wide-field, ground-based telescope that will survey half the sky every few nights in six optical bands from 320 to 1050 nm. It will explore a wide range of astrophysical questions, ranging from discovering “killer” asteroids, to examining the nature of dark energy. The LSST will produce on average 15 terabytes of data per night, yielding an (uncompressed) data set of over 100 petabytes at the end of its 10-year mission. Dedicated HPC facilities will process the image data in near real time, with full-dataset reprocessings on annual scale. A sophisticated data management system will enable database queries from individual users, as well as computationally intensive scientific investigations that utilize the entire data set. In this talk, I will give an overview of what LSST will deliver once operational, describe how the data management system is organized and talk about opportunities for use of the LSST software as early as today.

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27/03 - 10:00 am BRT

Roderik Overzier ( Observatório Nacional )

The Formation of Cosmic Structure through the eyes of new Surveys and Simulations

In the first part of this talk I will present an overview of the Millennium Run Observatory, a unique theoretical virtual observatory based on dark matter simulations, semi-analytic galaxy formation models, and virtual telescopes with a wide range of applications including modeling of (extra-galactic) surveys, testing of theoretical predictions, and the interpretation of observational data. In the second part of this talk, I will present an overview of several current and planned studies designed to investigate the formation of the large-scale structure at high redshifts, such as COSMOS, HETDEX, Subaru/Hypersuprimecam and the Subaru/PFS Survey.

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20/03 - 12:00 am BRT

Kevin Bundy ( IPMU/University of Tokyo )

The Manga Instrument and Survey

I will discuss the design, ongoing construction, and soon-to-begin execution of a new survey to obtain resolved spectroscopy for 10,000 nearby galaxies called Manga(Mapping Nearby Galaxies at Apache Point Observatory). Manga is one of three programs that make up the 6-year SDSS-IV project, beginning in August 2014. Manga will deploy 17 fiber-bundle IFUs across the Sloan 2.5m Telescope’s 3 degree field-of-view, targeting a mass-selected sample with a median redshift of 0.03, typical spatial resolution of 1-2 kpc, and a per-fiber signal-to-noise ratio of 5-10 in the outskirts of target galaxies. For each galaxy in the sample, Manga will provide maps and measured gradients of the age and chemistry of stellar populations, the gas-phase metallicity and star formation rates, as well as the velocity fields of both stars and gas. This unprecedented, rich data set will shed new light on the early formation history, ongoing growth, and eventual “death” via star-formation quenching of nearby galaxies.

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13/03 - 10:00 am BRT

Patrick Petitjean ( Institut d’AstroPhysique )

Quasar Science from SDSS

The SDSS-III BOSS (Baryonic Oscillation Spectroscopic Survey) project will produce a catalog of more than 200,000 quasars mostly at z>2. I will review the different fields that will be boosted by the availability of the catalog insisting on quasar absorption lines.

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27/02 - 04:00 pm BRT

Ani Thakar ( Johns Hopkins University )

SkyServer to SciServer: The Past, Present and Future of the SDSS CAS

The Sloan Digital Sky Survey Catalog Archive Server (CAS) and its Web portal, the SkyServer, have been in operation since 2001 and still going strong. The multi-terabyte SDSS catalog archive ushered in the era of big data, and has been a huge success by any measure, but that does not mean that it did not have its share of growing pains, mid-life crises and near-death experiences. This talk covers the good, e.g.,the extremely fruitful collaboration with Jim Gray that resulted in a new paradigm of data-intensive science with databases, and the extensive reusable building blocks that we built along the way; the bad, e.g. the lack of a plan to distribute data to mirror sites, and the impact on operational schedules and resources of the unprecedented data sizes; and the ugly, e.g. having to ditch our original object-oriented DBMS platform after spending several man-years of development effort on it. Through it all, the SkyServer has emerged as a oft-imitated and adapted model for data intensive science. As SDSS is poised to enter its fourth phase, the SkyServer is preparing to transition into an integrated and unified data infrastructure for big data in all sciences: SciServer.

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20/02 - 11:00 am BRT

Daniel Eisenstein ( Harvard University )

The Dark Energy Spectroscopic Instrument

I will describe the study of dark energy with modern large redshift surveys, focusing on the use of the baryon acoustic oscillation and redshift distortion methods. I will describe some of the latest results from the SDSS-III Baryon Oscillation Spectroscopic Survey, including our 1% measurement of the distance to redshift 0.57. I will then present the Dark Energy Spectroscopic Instrument (DESI), a new survey project proposed for the Kitt Peak National Observatory Mayall 4-m telescope. Using a new 5000-fiber spectrograph, DESI will conduct a vast spectroscopic survey of galaxies and quasars, surveying the Universe out to z=3.5 and producing very accurate measurements of the cosmic distance scale and evolution of large-scale structure.

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17/02 - 10:00 am BRT

Tsvi Piran ( Racah Institute of Physics, Hebrew University of J )

Neutron star mergers, Gamma-Ray Bursts and the Origin of Gold

Almost twenty-five years ago we suggested in a paper titled: “Nucleosynthesis, neutrino bursts and gamma-rays from coalescing neutron stars” that gamma ray bursts (GRBs) arise in neutron star mergers. We combined this prediction with earlier ideas of Lattimer and Schramm to suggest that in addition these mergers are the sources of heavy r-process material in the Universe, or put differently gold, silver and other rare heavy (A>130) elements. In recent years there is an accumulation of indirect evidence that short GRBs indeed arise from such mergers. Last June the Hubble Space telescope observed a very weak Infrared signal that followed a short GRB. This gave further indication for this link. This IR signal is interpreted as a Macronova, a short-lived IR signal that arises from the radioactive decay of debris from a compact binary merger. If the interpretation is correct this implies that indeed a significant amount of heavy r-process material was formed in this event. Combining this with the rate of observed short GRBs this implies that neutron star mergers produce most, if not all, heavy r-process material. Further observations of IR excess following short GRBs could confirm this hypothesis within a few years from now and resolve the last mystery concerning the origin of elements in the Universe.

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06/02 - 12:00 am BRT

Daniel Thomas ( University of Portsmouth )

Science with SDSS-IV/MaNGA

MaNGA (Mapping Nearby Galaxies at APO), which is part of the Sloan Digital Sky Survey IV, is an optical fiber-based multi-object IFU that will target 10,000 galaxies over a 6 year campaign with start of survey operations on July 1st 2014. MaNGA will allow the internal kinematics and spatially-resolved properties of stellar populations and gas inside galaxies to be studied as a function of local environment and halo mass for the very first time. I will review the current status of the project and provide an overview of the science that will be done with this project.

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30/01 - 12:00 am BRT

David Weinberg ( Ohio State University )

Cosmological Highlights from the Sloan Digital Sky Survey

I will describe some of the scientific highlights from the Sloan Digital Sky Survey (SDSS), concentrating on those connected to cosmology and galaxy formation. In the three phases to date,SDSS-I, II, and III, the Sloan collaboration has carried out several of the largest and most ambitious surveys of the distant universe and the Milky Way galaxy, with deep digital imaging over one third of the sky and spectroscopy of more than 2 million galaxies, 200,000 quasars, and half a million stars. Cosmological achievements include: probing the epoch of reionization with the most distant known quasars; comprehensively characterizing the properties of galaxies and the relations between galaxies and their parent dark matter halos; discovering ubiquitous substructure in the outer Milky Way and more than a dozen new companion satellite galaxies; mapping cosmic expansion over the last four billion years with more than 500 Type Ia supernovae; and, through its precision measurements of structure on very large scales, providing a central pillar of the standard cosmological model based on inflation, cold dark matter, and dark energy. I will review these highlights,with particular attention to recent progress in measuring the properties of dark energy through baryon acoustic oscillations. I will summarize plans and prospects for SDSS-IV, which begins in July 2014.

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22/01 - 12:00 am BRT

Nicolás G. Busca ( ON/LIneA )

First observations of Baryon Acoustic Oscillations in the LyA forests of BOSS quasars

The accelerated expansion of the Universe, discovered in the late 90’s using distant supernovae, was a surprise and remains an enigma. Is it due to a wrong understanding of gravity or to the presence of the mysterious “dark energy” Baryon acoustic oscillations in the primordial Universe provide us with a calibrated ruler imprinted in the distribution of matter. The BOSS experiment exploits this distance scale to measure the Hubble expansion rate with an intermediate redshift probe, galaxies at z~0.6, and a high redshift probe, the BAO-Lyα forests of distance quasars. In particular, the Lyα technique is novel and introduced for the first time by BOSS. In this talk, I will describe BOSS-Lyα and its cosmological context. I will discuss its first results that demonstrate, for the first time, the deceleration that preceded the accelerated expansion. I will also discuss the perspectives for the near future.

2013 31

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12/12 - 12:00 am BRT

Martha Haynes ( Cornell University )

The US Astronomy and Astrophysics Decadal Science Strategy Survey Process

Every 10 years, the US federal agencies (NSF, NASA and DOE) which support astronomy and astrophysics research ask the National Research Council (NRC) to conduct a survey of the state of space- and ground-based astronomy and astrophysics programs and to recommend priorities for the most important scientific and technical activities for the next decade. In this webinar I will discuss the process by which these “decadal surveys” are conducted by the NRC and some lessons learned along the way.

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05/12 - 12:00 am BRT

Luiz Nicolaci da Costa ( ON, LIneA )

LIneA: Status Report

O objetivo é apresentar uma breve revisão dos acontecimentos mais importantes do LIneA durante o ano de 2013, uma discussão das metas a serem atingidas em 2014 e os desafios sendo atualmente enfrentados pelo laboratório.

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28/11 - 12:00 am BRT

Simon White ( Max-Planck-Institut für Astrophysik )

The formation and evolution of the galaxy population

Recent observations of the high-redshift universe have characterized the initial conditions for nonlinear structure formation over the full range of scales responsible for dwarf and giant galaxies, galaxy clusters and the large-scale cosmic web. At the same time, wide-field spectroscopic and photometric surveys have measured the abundance and clustering of low-redshift galaxies as a function of mass, size, morphology, kinematic structure, gas content, metallicity, star formation rate and nuclear activity, while deep surveys have explored the evolution of several of these distributions to z>3. Galaxy population simulations aim to interpret these observations within the LCDM structure formation paradigm, thereby constraining the complex, diverse and heavily interconnected astrophysics of galaxy formation. I will show that recent simulations are broadly consistent with the galaxy abundances and clustering seen both in wide-field and in deep surveys, Such simulations provide predictions for topics as different as galaxy-galaxy lensing, the triggering and duty cycles of AGN, and the evolution of Tully-Fisher, mass-size and mass-metallicity relations. They show galaxy assembly histories to be strongly constrained by the structure formation paradigm, giving insight into issues such as internally versus externally driven evolution, inflow versus winds, major versus minor mergers, in situ versus ex situ star formation, and disks versus bulges. In addition, simulations can now be adapted to represent any chosen LCDM-like cosmology, allowing a first assessment of whether galaxy formation uncertainties will limit our ability to do precision cosmology with galaxy surveys.

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14/11 - 12:00 am BRT

Markus Demleitner ( Heidelberg University )

The VO And Why It Matters To You

In the most technical words, the Virtual Observatory (VO) is an effort to enable uniform and efficient access to astronomical data. With more glitz, it is like the Web and Google, only for data. In this talk I will try to convice you that what sounds incredibly tedious and boring in reality is exciting and useful to your research. Thus, after some motivation filling in the gaps in the above definitions, I will go on describing some of the key VO technologies and the ways to use them. I will close pointing out why you should also publish to the VO and that that probably is not hard.

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07/11 - 12:00 am BRT

Stephane Arnouts ( Laboratoire d’Astrophysique de Marseille )

The UV side of galaxy evolution

During the last decade a clear picture has emerged about the evolution of SFR and Stellar Mass densities from 0: the SF activity peaks at z~1-2, followed by a drop of a factor ~10-20 up to now. Exploring the evolution of the galaxy properties with cosmic time and environment is one approach to understand the physical processes that regulate the star formation activity. To this end a wealth of multi-wavelength surveys have been used with a variety of SF indicators (UV/Ha/OII/FarIR/radio/..). Among them, UV is of particular interest since it is available over the entire redshift range. Although it is severely affected by dust, if this issue can be solved, then UV offers a unique opportunity to explore the low mass world (10^8 in contrast to other estimators like the Far-IR or optically selected surveys dominated by massive galaxies. This is interesting since the Star Formation Efficiency is thought to be a balance between gas accretion and feedback processes which may differ on both side of the mass function knee (M~10^10.3 Mo). In this talk, I will first revisit our original GALEX luminosity functions based on a new photometric algorithm developed for GALEX images. By using the Far-Infrared observations in the COSMOS field, I will present a new method to predict the dust amount (or infrared excess, IRX=Lir/Luv) in galaxies based on a single color vector combining NUV, r, K luminosities (which can be of interest for future optical/NIR surveys). With this in hand, I will explore the evolution of the SFR Density up to z=1.5, the relative contribution of low and massive galaxies, and its implication on the general framework of galaxy formation.

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24/10 - 12:00 am BRT

Manda Banerji ( UCL )

The VISTA Hemisphere Survey

I will present an overview of the near infrared VISTA Hemisphere Survey. VHS is the largest near infrared survey undertaken to date and on completion, will provide J and K-band imaging over most of the southern celestial hemisphere to a depth of 30x fainter than 2MASS. I will describe how the VHS data will complement optical data from the Dark Energy Survey, in particular providing more accurate photometric redshifts for DES galaxies. I will also present some other science applications of the new VHS data, in particular in identifying high redshift galaxy clusters, luminous red galaxies and populations of both obscured and high redshift quasars.

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17/10 - 12:00 am BRT

Daniel Oliveira ( IC-UFF )

Scientific Workflow Management in Cloud Environments

Most of the existing large-scale scientific experiments modeled as scientific workflows are computing intensive and require a huge amount of computing resources (typically distributed) to execute thousands of tasks in High Performance Computing (HPC) environments, such as clusters or grids. In recent years, cloud computing environments start posing as a promising HPC environment by providing elastic features that can be instantiated on demand, without the need for scientists to acquire its own infrastructure. However, the effective use of clouds to execute workflows that demand HPC presents many open, yet important, challenges. As scientists execute scientific workflows that require HPC, it is difficult to decide the amount of resources and how long they will be required beforehand, since the allocation of these resources is elastic. In addition, scientists have to deal with how to capture distributed provenance information and fluctuations in the distributed environment resources. This presentation introduces SciCumulus, which is an approach to adaptively manage the parallel execution of scientific workflows in clouds. The SciCumulus verifies the available computing power, dynamically adjusts the allocation of tasks and scales the cloud environment to achieve a better performance, without compromising distributed provenance gathering. The experiments presented in this thesis showed the benefits of the adaptive approach of SciCumulus that evidenced a performance increase of up to 37.9% compared to traditional approaches that provide parallelism in the clouds with the advantage of offering a service for provenance capture at runtime.

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19/09 - 12:00 am BRT

Richard Kron ( Fermilab )

The Dark Energy Spectroscopic Instrument (DESI)

The Dark Energy Spectroscopic Instrument (DESI) is a planned 5000-fiber, 3-degree FOV system to be operated on the 4-m Mayall Telescope on Kitt Peak, Arizona. The project is motivated by placing tighter constraints on cosmological parameters via large-scale structure starting in 2018 (i.e. roughly between the end of the Dark Energy Survey and the beginning of the LSST era). The sources selected for redshift measurement will be a combination of emission-line galaxies, luminous red galaxies, and quasars (specifically Lyman alpha absorption systems). The plan is to cover ~ 15,000 square degrees of sky and obtain 20 to 30 million redshifts in less than 5 years. This talk will cover these basics; describe the nature of the emerging DESI partnership and the technical status of the project; and list some open issues.

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12/09 - 12:00 am BRT

Jean-Paul Kneib ( Ecole polytechnique fédérale de Lausanne )

Mapping the Universe with Massive Spectroscopic Redshift Surveys

The vision of our Universe has changed dramatically in the last century, this is of course the results of a better understanding of the physics but also thanks to the growing number of observations of distant galaxies and quasars. With the discovery of the accelerating expansion of the Universe at the turn of the last millennium, cosmologist are now faced to a new mystery that was nicknamed Dark Energy. Important new resources are thus now dedicated to map the large scale structures of the Universe, and a number of new facilities are planned. In particular, I will focus on the recent advances and projects regarding the mapping of the Universe with massive spectroscopic redshift surveys. I will present the latest results from the SDSS/BOSS project focusing on the BAO measurement. Then I will describe what will achieve the next generation spectroscopic surveys, starting with SDSS/eBOSS survey that will start in 2014, and followed by DESI (2018), PFS (2018) and Euclid (2020).

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05/09 - 12:00 am BRT

Stefan Müller ( FHNW )

Dark Energy Survey – Software Management

The Data Management team of the Dark Energy Survey (DESDM) is responsible to create data products for the scientists from the raw images made with the Blanco telescope. The data quality is directly affected by the software quality. In this talk I will report on our efforts to ensure traceablitiy and quality of the DESDM software. The heart of the new software management system is EUPS, a package management tool. Around this tool we are building a system for continuous integration, documentation and release management. While our work is still in progress, DESDM has already started migrating their production pipelines to the new system. With several active users, and hundreds of software packages, the system is now in everyday use.

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29/08 - 12:00 am BRT

Flávia Sobreira ( Observatório Nacional )

Large-scale analysis of the Blind Cosmology Challenge Angular Correlation Function

The study of the large scale structure of the Universe has became a big challenge when analyzing a wide area photometric galaxy survey. In this presentation I will show the results of using the full shape of the 2-point galaxy angular correlation function to constrain cosmological parameters from the BCC-Aardvark when considering the 5000 sq degree DES footprint.

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22/08 - 12:00 am BRT

Nelson Pinto ( CBPF )

Modelos cosmológicos sem singularidade e confronto com as observações

Discutirei os contextos físicos onde a singularidade inicial do modelo cosmológico padrão pode ser evitada, enfatizando os modelos que possuem uma fase de contração anterior à presente fase de expansão do Universo. Em seguida, apresentarei as possíveis consequências observacionais desta fase contrativa primordial, sobretudo nas anisotropias da radiação cósmica de fundo, comparando com os resultados oriundos dos modelos inflacionários, visando construir observáveis que possam diferenciar estes dois tipos de modelos cosmológicos.

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15/08 - 12:00 am BRT

Marcos Lima ( University of Sao Paulo )

Cosmology from Galaxy Clusters

Galaxy clusters probe the tail of the cosmological density field and constitute the largest collapsed structures in the Universe. Their abundance is exponentially sensitive to density perturbations and to the underlying cosmology. In this presentation I discuss some of the aspects related to the extraction of cosmological parameters from the observed counts of clusters in optical surveys.

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08/08 - 12:00 am BRT

Michael Blanton ( University of New York )

The Future of the Sloan Digital Sky Survey

I describe plans for the next-generation Sloan Digital Sky Survey, to begin in July 2014, and which consists of three programs, APOGEE-2, MaNGA and eBOSS. APOGEE-2 will use both the Sloan Foundation Telescope at Apache Point and the du Pont Telescope at Las Campanas to study Galactic archaeology with high-resolution near-infrared spectroscopy. MaNGA will develop fiber bundle technology for the BOSS spectrograph to perform multiplexed spatially resolved spectroscopy with an unprecedented combination of wavelength coverage and resolution for 10,000 nearby galaxies. eBOSS will study the Universe’s expansion using a massive survey of galaxies and quasars. eBOSS will also perform follow-up spectroscopy on X-ray and variable sources, making it both the largest and most broadly selected quasar survey. I will show how this innovative set of programs will lead to a better understanding of cosmology and galaxy formation, as well as stellar and exoplanetary astronomy.

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01/08 - 12:00 am BRT

Rogério Rosenfeld ( IFT-UNESP )

Some thoughts on the cross-correlation of cluster counts and ACF

In this seminar I’ll show some preliminary ideas on how to use the Halo Model to estimate the cross-correlation of cluster counts and the ACF.

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18/07 - 12:00 am BRT

Angelo Fausti ( LInea )

Portal review, next developments and how you can contribute

We had a successful review of the portal at Fermilab last week. While a formal report is being prepared by the review panel we anticipate that the priorities for the next months are Quick Reduce, QA coadd (for tests at NCSA and for desdm releases) and the E2E infrastructure for the creation of Value-Added Catalogs. In this presentation we’ll discuss recent developments in the portal and how you can contribute in each of these projects. Angelo Fausti and Patricia Bittencourt (LInea)

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11/07 - 12:00 am BRT

David Latham ( Havard University )

The Search for Habitable Planets

We live at a very special time in the history of astronomy. We are poised to discover and characterizes exoplanets enough like the Earth that we can imagine life as we know it could arise and be comfortable. We are seeking rocky planets at the right distances from their host stars for water to be liquid on the surface, and with a secondary atmosphere that might even show evidence for biogenic gases.Transiting planets are where the present action is, because they can provide masses and radii for planets, and thus the bulk properties such as density and surface gravity that constrain our models of their interior structure and composition. Are they ice giants like Uranus and Neptune, or rocky worlds like the terrestrial planets, or maybe something in between with lots of water or extended atmospheres of hydrogen and helium. NASA’s Kepler mission has provided lots of small planet candidates, but the bottleneck for characterizing them is the ultra-precise radial velocities needed for confirming and characterizing the planets with mass determinations. HARPS-N has recently come into operation at the Telescopio Nazionale Galileo on La Palma and is now contributing to the follow up of Kepler candidates, but we need better ways to correct for astrophysical effects that distort the radial velocities, and still better velocity precision if we hope to reach the level of 9 cm/s induced by a true Earth twin in a one-year orbit around a star like the Sun. Kepler looks at only one four hundreth of the sky. We need an all-sky survey for transiting planets to find the nearest and brightest examples for radial-velocity follow up and studies of planetary atmospheres with missions like the James Webb Space Telescope and G-CLEF spectrograph on the Giant Magellan Telescope. Our long-range goal is to see if the atmospheres of any potentially habitable planets actually show evidence for biogenic gases that have been produced in large enough quantities to impact the biosphere and be detected remotely. If we detect spectroscopic biomarkers that can only be present if they are continually replenished by life, then we can point at that star and speculate that we may not be alone in the universe.

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04/07 - 12:00 am BRT

Kathy Romer ( University of Sussex )

XMM Clusters through DECam Eyes

Using data from the Scientific Verification phase of the Dark Energy Survey (DES-SV), we will present results derived from deep, multi-colour, images of XMM clusters made using the DECam instrument. Some of these clusters are well known (e.g. The Bullet Cluster), but many of these clusters have been confirmed for the first time using DECam data. DECam images and preliminary optical to X-ray scaling relations, will be shown. We will describe the methods used to generate XMM images of more than 600 clusters that overlap with the DES-SV footprint. These methods have been adapted from those used in the XMM Cluster Survey (XCS). Existing results from the XCS will be reviewed.

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20/06 - 12:00 am BRT

Alex Kim ( Lawrence Berkeley National Laboratory )

The Bright Future of Supernova Cosmology

Type Ia supernovae (SNe Ia) remain a powerful probe of dark energy, giving the best current measurements of the accelerating expansion of the universe. Although results are limited by systematic uncertainties, new analyses modeling supernova light curves as a Gaussian process show significant improvement in calibrating SN Ia absolute magnitudes. Reduction of systematic ncertainties and better experiments will keep SNe Ia a critical contributor to our quest to understand dark energy.

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13/06 - 12:00 am BRT

Scott Dodelson ( University of Chicago )

Cross-Correlations

The standard cosmological lore is that galaxy survey and cosmic microwave background experiments open up a window on fundamental physics such as dark energy and dark matter. The four distinct probes enabled by surveys — Baryon Acoustic Oscillations, Clusters, Gravitational Lensing, and Supernovae — together with a pristine view of the early universe via the CMB allow us to determine cosmological parameters such as the equation of state of dark energy. I argue that this paradigm is breaking down, as we come to realize that the four probes are all correlated with one another and with the CMB itself. How to proceed is the subject of a raging debate, with many possible routes and assumptions. I give a few examples from the Dark Energy Survey.

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06/06 - 12:00 am BRT

August Evrard ( University of Michigan )

Synthetic Skies: a Brief Tour of Computational Cosmology

In 1970, Jim Peebles modeled the Coma cluster of galaxies with 300 point masses on a gigantic CDC “supercomputer”. Since then, simulations of cosmic structure have grown dramatically in scope and scale. In this talk, I will review the history and survey current trends in simulation methodology, then describe methods used to produce synthetic skies for the Dark Energy Survey. I will close with some technical and social challenges, including coordinating data management of global simulation assets and barriers to continued growth of simulation scale.

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23/05 - 12:00 am BRT

Diego Capozzi ( University of Portsmouth )

Constraining galaxy formation and its influence on the dark – baryonic matter relationship with future galaxy surveys

The current picture of structure formation predicts that structures (or haloes) form hierarchically due to the dark matter clustering. However, the picture portrayed for dark matter might not be applicable to baryonic matter (constituting the galaxy stellar and gas content), because it is not subject only to gravity. In fact, despite the general belief that galaxies form hierarchically (the majority of semi-analytic models are built on this premise), several are the observations this scenario struggles to reproduce (e.g., the so-called downsizing). Furthermore, the influence that the physics driving galaxy formation has on galaxy-structure properties is still unresolved. I will introduce these topics and describe how they can be addressed by using data from current and future galaxy surveys (DES, BOSS, SERVS, SDSS) in the general field and in galaxy structures (clusters and groups). In particular, I’ll focus on galaxy luminosity and stellar mass functions, downsizing process, halo occupation distribution and the detection of 3

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16/05 - 12:00 am BRT

Sarah Bridle ( University of Manchester )

Quantifying Dark Energy using Cosmic Lensing

I will describe the great potential and possible limitations of using the bending of light by gravity (gravitational lensing) to constrain the mysterious dark energy which seems to dominate the contents of our Universe. In particular we have to remove the blurring effects of our telescopes and the atmosphere to extreme precision, and account for possibly coherent distortions of galaxy shapes due to processes in galaxy formation. I will discuss these issues in more detail and review some recent progress in tackling them, putting them into the context of the upcoming Dark Energy Survey.

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09/05 - 12:00 am BRT

Martin Crocce ( University of Barcelona )

Redshift Space Distortions from combined Photometric Samples

In this talk I will discuss the possibility of measuring redshift space distortions from angular auto-correlations in photometric surveys such as DES or PanSTARRS, if galaxies are selected in photometric redshift bins. In particular I will discuss the gains (e.g. in constraining the growth rate of structure) obtained from including as observables also the cross-correlations between bins, that introduce radial information. And show that further improvements can be achieved by combining two galaxy populations with different biases over the same photometric sky area. In all, our findings show that a survey such as DES should constrain the evolution of $f(z)timessigma_8(z)$ in few bins beyond $zsim 0.8-0.9$ at the $10%$ level per-bin. This is perfectly compatible with recent constrains from lower-$z$ spectroscopic surveys and highlights a new and exciting application of upcoming photometric data.

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02/05 - 12:00 am BRT

Martin Groenewegen ( Royal Observatory of Belgium )

The Herschel MESS program: an overview

MESS, Mass loss of Evolved Stars, is a Herschel guaranteed time key program of over 300 hours that observed roughly a hundred evolved stars in our galaxy, both using photometry and spectroscopy. Although the range of objects varies wildly, from AGB stars and Planetary Nebulae, to LBVs and SN remnants, the focus point of all investigations has been the mass loss process. I will be giving an overview of the program and the results obtained so far.

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25/04 - 12:00 am BRT

Nikhil Padmanabhan ( Yale University )

Towards 1% measurements of cosmological distances with cosmic sound

Measuring the accelerated expansion of the Universe with the goal of better understanding its underlying physics is one of the leading programs in cosmology today. The baryon acoustic oscillation technique is one of the foremost tools in our toolbox today. This talk will explain the underlying physics of this method and the reasons it is extremely robust to observational and theoretical systematic errors. I will then present the latest results from the SDSS and BOSS surveys, currently the most precise distance constraints from this method. These will include a new analysis technique to undo the effects of the nonlinear evolution of the density field and partially “reconstruct” the initial density field, and can reduce the distance errors by a factor of 1.7. I will discuss the implications of these measurements, and will conclude by discussing prospects for improvements in the immediate and not-so-immediate future.

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18/04 - 12:00 am BRT

Keivan Stassum ( University of Vanderbilt )

Exoplanet discoveries, brown dwarfs, and fundamental stellar astrophysics from KELT, MARVELS, and Kepler

The advance of ultra-precise radial velocities and light curves for large numbers of stars is opening the door to fundamental discoveries regarding exoplanets, brown dwarfs, and of the stars that host them. This talk will review in particular the recent discoveries of the brightest known transiting exoplanet host stars with the ground-based survey, discovery of brown dwarf companions to stars with the MARVELS radial-velocity survey, and efforts to determine the relative chemical abundances of wide binaries hosting planets. Finally, we present an exciting new discovery using Kepler light curves of a new “fundamental evolutionary plane” for stars involving measures of their photometric variations. Using this new fundamental plane we can measure the surface gravities of stars to better than 0.06 dex using only a standard light curve, with no need for asteroseismic analysis. We also are able to explain the RV jitter of stars using this new fundamental plane.

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21/03 - 12:00 am BRT

Chris Miller ( University of Michigan )

Measuring the Masses of Galaxy Clusters using their Gravitational Potential

Dynamical processes within galaxy clusters are governed by the Newtonian gravitational potential. This potential (or its derivative) is observed in the motions of tracers: the gas and galaxies. I will discuss how spectroscopic follow-up of galaxy clusters can be used to infer the masses of galaxy clusters using three techniques: virialization and the velocity dispersion; the radius/velocity phase-space distribution function and the Jean’s Equation; and the escape velocity. I will compare how well the velocity dispersion and the escape velocity infer halo masses in the Millennium simulation after accounting for realistic observable constraints, like targeting and color/magnitude selection. Finally, I will discuss how direct measurements of the potential can address predictions from f(R) modified gravity.

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14/03 - 12:00 am BRT

Ofer Lahav ( University College London )

The benefits from combining imaging and spectroscopic surveys

The talk will discuss the landscape of imaging and spectroscopic surveys, and how combining them could improve contrail of systematics. In addition, such combination could help to distinguish between models of Dark Energy and Modified Gravity.

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05/03 - 12:00 am BRT

Joe Zuntz ( University of Manchester )

Cosmic Lensing with the Dark Energy Survey

Cosmological weak lensing is a method of probing the universe by measuring minuscule distortions in the shape of galaxies half the universe away. As light from these galaxies travels to us it cross the cosmos it passes through regions of matter whose gravity acts like a lens, changing the image shape. If we can accurately measure the distortion we can therefore map the universe. The Dark Energy Survey is a telescope project to measure this lensing effect. WIth the help of Brazilian computing facilities the newly built DECam on the Blanco telescope in Chile will make the biggest map of the universe ever created, and will help us unlock the secrets of the Dark Energy effect, the acceleration of the expansion of the cosmos over billions of years. In this talk I’ll discuss the promise, power, and problems of cosmic lensing, including some quite surprising challenges.

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28/02 - 12:00 am BRT

Fábio Porto ( LNCC )

Big Data Analysis in Astronomy

In this talk we will make a summary of the EMC Big Data Summer School, held at UFRJ-COPPE from 4 to 7 of February 2013. We will focus on the talks and discussions related to big data processing of distributed databases using the Hadoop framework. We will draw a comparison among different distributed database architectures and their impact on the parallel evaluation of workflows and a possible integration with Hadoop. Next, we will discuss strategies for partitioning the data based on a known workload that can be used to integrate with Hadoop.

2012 17

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22/12 - 12:00 am BRT

Mauro Barbieri ( University of Padua )

Trilegal – New improvements

In this talk I will present the new improvements that I have added to stellar population synthesis code TRILEGAL : extinction model, binary evolution, variable stars, asteroseismic parameters, planet populations and their probability of detection. I will present also the results of a study of giant stars observed by CoRoT and how TRILEGAL can be used on ensemble asteroseismology studies.

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06/12 - 12:00 am BRT

Bruno Coelho ( CAAUL, University of Lisboa )

Beneath the Morphology of Quasi-stellar Objects

In the framework of the unified theory the classification of AGNs is largely a matter of line-of-sight perspective. Naturally a less schematic classification must consider the object interaction and merger history, dust contents, star formation waves, the rate and gyro direction of the central massive black hole, and the enrichment of the off accretion disk shells or regions. Nonetheless the entrusted relationship between the mass of the central black hole, its luminosity, and the mass and luminosity of the host galaxy must generally hold. Since by optical ground observations quasars are essentially quasi stellar objects, an apparent paradox hence arises by which the more massive and luminous a host galaxy is, the more luminous the quasar tends to be, thus making the more invisible by contrast the host galaxy. The presence of the host galaxy can be inferred also from color studies and from departures of the compound PSF of quasar and host galaxy to the purely pointlike stellar PSFs. This methodology can be used to classify morphologically the quasars observed out the atmosphere, as will be the case of the Gaia mission, enabling to derive a centroid astrometrically more precise than if a stellar PSF would have been applied for the centroid determination. We present the methodology to calculate morphological indexes, the observational programs in course, and a comprehensive analysis of images from the SDSS QSO catalogue.

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29/11 - 12:00 am BRT

Daniel Thomas ( University of Portsmouth )

Galaxy evolution with BOSS

I will give a brief overview over the BOSS/SDSS-III survey and its potential for galaxy evolution studies. I will particularly focus on our recent work on characterising the emission line and kinematic properties of BOSS galaxies, and their use to study the dynamical and dark matter properties of massive galaxies with look-back time.

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18/10 - 12:00 am BRT

Will Percival ( University of Portsmouth )

Cosmological Measurements from Galaxy Clustering

First results are presented from galaxy clustering measurements in the Baryon Oscillation Spectroscopic Survey (BOSS), which is part of SDSS-III. Data release 9, which was publicly released in July, contains 327,349 massive galaxies with an effective redshift z=0.57 covering 3,275 square degrees. Assuming a concordance LCDM cosmological model, this is equivalent to 0.77 h^{-3} Gpc^3, and represents the largest sample of the Universe ever surveyed at this density. In addition to reviewing the physics behind these techniques, I will present results from Baryon Acoustic Oscillation (BAO), Redshift-Space Distribution (RSD) measurements. I will then look ahead to future projects.

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11/10 - 12:00 am BRT

David Gerdes ( University of Michigan )

Photometric Redshifts Using Boosted Decision Trees

Photometric redshifts are essential to the next generation of large optical surveys, including DES, as the number of galaxies that will be observed far exceeds the ability to measure redshifts spectroscopically. Techniques for measuring photometric redshifts generally fall into two categories: template-based methods, and empirical or training-set-based methods. In this talk I will describe an empirical method, ArborZ, based on a machine-learning technique called Boosted Decision Trees. I will describe the training procedure and present results of the algorithm on SDSS data. I will also discuss the algorithm’s performance in the realistic case when the properties of the training set and the target photometric set differ. I’ll conclude with implications for DES.

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04/10 - 12:00 am BRT

Alberto Krone-Martins ( University of Lisboa )

Unsupervised Photometric Membership Assignment in Stellar Clusters

One of the most ancient problems in the photometric study of stellar clusters is the assignment of membership for its stars. Although several approaches exist for attacking this problem, they usually involve the adoption of complex theorethical models for the photometric data (isochrones) and/or the selection and use of control fields, possibly biasing some results. We have developed a data-driven, fully automated and unsupervised method to perform membership assignment in Stellar Clusters using photometric and spatial data, which is independent from complex theorethical models, as well as from the adoption of observational control fields. Our method is based on an iterative solution, and relies on Principal Component Analysis, clustering algorithms and kernel density estimations. Optionally, it also allows the user to take into account error models and missing data. We will present a description of the method, results obtained with its application to a set of realistic simulations as well as results obtained from analysis of real data of selected Open Clusters.

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27/09 - 12:00 am BRT

Eduardo Ogasawara ( CEFET/RJ & COPPE/UFRJ )

An Algebraic and Parallel Approach for Scientific Workflows using Chiron

Large-scale scientific experiments based on computer simulations are typically modeled as scientific workflows, which facilitate the sequencing of different programs. These scientific workflows are defined, executed and monitored by Scientific Workflow Management Systems (SWfMS). As these experiments manage large amounts of data, it is interesting, if not essential, to execute them in High Performance Computing (HPC) environments, such as clusters, grids and clouds. However, few SWfMS provide parallel support and they usually lack a run-time provenance support mechanism. Also, the existing parallel SWfMS have limited primitives to optimize workflow execution. To address these issues, we developed an algebraic approach to specify the scientific workflow, and it leaded to the implementation of Chiron: An Algebraic-Based parallel scientific workflow engine. Chiron has a native distributed provenance gathering mechanism and can perform algebraic transformations to obtain better execution strategies. Chiron is efficient in executing scientific workflows, with the benefits of bringing room for declarative specification and run-time provenance support.

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20/09 - 12:00 am BRT

Michael Bucha ( University of Zurich )

Modeling the Dark Energy Survey

The Dark Energy Survey (DES) is a project to map out galaxies in 5000 sq deg of the southern sky with the intent of providing tighter constraints on the nature of dark energy using, among other methods, galaxy clusters, weak lensing, and baryon acoustic oscillations. DECam, a wide field camera constructed for the project, recently saw first light and is currently undergoing commissioning. As the beginning of the survey is now imminent, the DES project is in its final stages of preparing for the incoming data. One aspect of this is a project known as the Blind Cosmology Challenge (BCC). The BCC is an ambitious project designed to test our ability to accurately extract cosmology from the DES data set by means of running the cosmological analysis pipeline on a set of synthetic galaxy catalogs designed to model the predicted DES galaxy catalog. A suite of these catalogs are being created using a range of underlying cosmologies. In this talk, I will review the ongoing efforts to create these synthetic, wide area galaxy catalogs, that probe the full range of environments and scales we anticipate the survey to probe. This is a challenging project that requires realistically modeling a wide range of galaxy properties, such as photometry, clustering, shape noise, and lensing effects. Additionally, I will present some initial results from evaluating the behavior of cluster finders on such catalogs.

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13/09 - 12:00 am BRT

Carlos Cunha ( University of Stanford )

Problemas radiais e angulares em estudos cosmológicos de grandes escalas

Esta apresentação será dividida em duas partes. Parte I: Requerimentos para a calibragem angular em estudos de estrutura de grande escala. O agrupamento de galaxies em grande escala é rico em informações sobre a origem e composição do Universo. Porem, é muito difícil quantificar a seleção da amostra coletada durante vários anos em uma vasta área do céu. Nessa palestra, apresentarei um formalismo para estimar os erros sistemáticos induzidos por efeitos na selecao da amostra e identificarei os requerimentos para a calibragem do Dark Energy Survey (DES). Parte II: Requerimentos para acompanhamento espectroscópico de estudos fotométricos. Redshifts são uma propriedade essencial em cosmologia. Por limitações de tempo e dinheiro, estudos cosmológicos fotométricos dependem de estimativas intrinsincamente imprecisas de redshifts, os chamados photo-zs. Os photo-zs nao devem ser utilizados em analises cosmológicas a menos que as incertezas sejam quantificadas com precisão. Tipicamente, as incertezas sao caracterizadas usando uma amostra de galaxias com redshifts determinados espectroscopicamente. Porem, redshifts espectroscopicos nao sao perfeitos, e as amostras são incompletas e contem redshifts incorretos. Nessa palestra, descreverei problemas em amostras de redshifts espectroscopicos e como utiliza-los para a calibragem de erros de redshifts fotométricos.

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06/09 - 12:00 am BRT

Rodney Gomes ( Observatório Nacional )

Origem dos TNO’s: o que sabemos e o que resta saber

G. Kuiper previu que deveria existir um disco de objetos de gelo além da órbita de Netuno. Estes corpos seriam remanescentes do disco de planetesimais original, cujos componentes não conseguiram se aglutinar para formar planetas por ser a região trans-netuniana pouco densa para promover uma acreção de planetesimais até o tamanho planetário. Este disco deveria ser dinamicamente frio (órbitas pouco excêntricas e pouco inclinadas), poderia se extender até ~ 100 UA e teria ter uma massa total em torno de algumas massas da terra. Embora a descoberta dos primeiros objetos do Cinturão de Kuiper tenha parcialmente satisfeito a previsão de G. Kuiper, na verdade as órbitas dos TNO’s se mostraram bem diferentes do esperado, ou seja, excêntricas, inclinadas e com uma borda externa em torno de 50 UA. Além disso, a massa total estimada para o Cinturão de Kuiper certamente está abaixo de 0.1 massa da Terra e existem fortes evidências da existência de duas populações distintas dentro do Cinturão. Neste seminário, estarei apresentando o que já foi desenvolvido para explicar a peculiar estrutura orbital do Cinturão de Kuiper e sua relação com a evolução primordial do Sistema Solar. Estarei, ainda, discorrendo sobre os pontos ainda não totalmente esclarecidos da estrutura dinâmica dos TNO’s e os cenários que estariam por detrás da possível explicação desses pontos.

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30/08 - 12:00 am BRT

Roberto Cid Fernandes ( UFSC & IAA-Granada )

Galaxy growth in 1 and 2D: 1st results from the CALIFA survey

Spectral synthesis of galaxies is the science/art of digging as much information as possible from galaxy spectra. In the last decade, evolutionary synthesis models with decent spectral resolution in the optical have promoted huge advances in this area, which, combined with the avalanche of data has lead to substantial progress in our understanding of galaxies. The STARLIGHT code is one such tool in this business. It performs Angstrom-by-Angstrom fits of galaxy spectra combining models of simple stellar populations of various ages and metallicities. It has been employed to address a variety of issues, from problems where one seeks information on stellar population mixtures (a.k.a. Star Formation Histories), to others where one is more interested in getting rid of stellar light in order to measure emission lines, to study stellar kinematics, and even to test the ingredients (SSP models) themselves. This talk will (1) briefly review the basics of spectral synthesis and illustrate its power as a tool to study galaxy evolution in 1D (ie, SDSS-like integrated spectra), and (2) move on to the main course: We will present the 1st results of the application of STARLIGHT to the 1st 100 galaxies observed in the CALIFA survey. CALIFA is collecting data cubes (integral field spectroscopy) for 600 galaxies (~ 1000 spectra per target) spread over the color magnitude diagram. Besides its own importance, this pioneer IFS survey serves as a test-bed for future projects, like SAMI and MaNGA. We have developed an end-to-end pipeline to processes data cubes through STARLIGHT, thus allowing us to resolve galaxies in time and space. Dissecting galaxy spectra as a function of position is showing us how the different morphological components of galaxies build their mass and metals over time, and promises to provide important clues for galaxy evolution models in general.

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23/08 - 12:00 am BRT

Eduardo Bezerra ( CEFET/RJ )

Aplicações da Computação para Astronomia: Mineração de Dados e Simulação

O grande volume de dados acumulado por observações em Astronomia tem suscitado a demanda por técnicas computacionais para descobrir padrões e tendências relevantes subjacentes a esses dados. De outro lado, esses mesmos dados acumulados permitem a identificação de parâmetros da dinâmica de alguns fenômenos físicos astronômicos de tal forma que esses parâmetros podem ser usados para a produção de simulações computacionais dos fenômenos. Nesse seminário, são apresentadas introduções a algumas técnicas de mineração de dados e de simulação computacional, e são apresentadas possibilidades de aplicação dessas técnicas para suporte à Astronomia.

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17/08 - 12:00 am BRT

Thiago Gonçalves ( -- )

O estudo de galáxias Lyman break em baixo redshift

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16/08 - 12:00 am BRT

Eduardo Balbinot ( UFRGS, LineA )

FindSat – Hunting for sparse structures in the halo

The census of MW satellites and their distribution as a function of Galactocentric distance, mass, metallicity among other properties, will help recover the history of mass assembly in our Galaxy and test structure formation scenarios.The Milky Way has two distinct groups of satellite galaxies when we consider their year of discovery. 9 satellites were known up to the 1970s. About 15 new small galaxies were discovered with the wide and homogeneous surveys from the past 15 years, such as SDSS and 2MASS. The Dark Energy Survey (DES) is anticipated to lead to the detection of dozen more such systems, assuming that their stellar nature can be distinguished from the much larger number of galaxy clusters to be sampled. With this goal in mind we are developing FindSat, an algorithm that searches for new satellite galaxy and star clusters candidates as overdensities of stellar sources in a large photometric survey. FindSat was validated using SDSS DR7 data and successfully recovered all previously identified MW satellites with these data. It was then applied to DR8 data in the Southern Galactic region of the BOSS survey. 30 candidates were found, for which deeper follow up images from CFHT are being taken. We will present our very preliiminary results from these new images, including one already confirmed new MW satellite.

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09/08 - 12:00 am BRT

Karin Menendez ( Observatório do Valongo )

Galáxias Submilimétricas – Uma População Enigmática Em Alto Redshift

Galáxias ultraluminosas no infravermelho (L>1012Lsolar; ULIRGs) são raras no universo local, mas dominam a densidade de energia co-móvel em alto redshift (z>2). Devido à grande abundância de poeira, muitas destas ULIRGs são fracas no óptico e foram descobertas apenas recentemente devido à emissão térmica da poeira em comprimentos de onda submilimétricos. Estudos detalhados das chamadas galáxias submilimétricas (SMGs) revelam: morfologias complexas associadas a mergers; taxas de formação estelar de até 1000 vezes a taxa na Via Láctea; e a presença de núcleos ativos (AGN) que indica a coexistência de formação estelar intensa com o crescimento rápido de buracos negros supermassivos. Com um redshift médio de z~2 e a capacidade de formar o grosso da massa estelar de uma galáxia elíptica em ~108 anos, as SMGs são candidatas viáveis a progenitoras das galáxias de maior massa no universo local. Assim, estes objetos formam uma população extremamente interessante para o estudo da parcela mais massiva em modelos atuais de formação e evolução de galáxias. Apresentarei uma revisão breve do que conhecemos sobre estas galáxias e compartilharei alguns dos resultados mais recentes baseados em dados H-alpha coletados com o espectrógrafo de campo integral OSIRIS no telescópio Keck, Hawaii. Este instrumento foi construído para funcionar com o sistema de Óptica Adaptativa com Estrela Laser que permite uma resolução até 10 vezes maior que estudos anteriores limitados pelo seeing atmosférico. Portanto, estes resultados são nossa primeira visão detalhada da distribuição do gás ionizado nas SMGs. Estudos como estes nos preparam para uma nova era de detalhe na distribuição de combustível molecular em galáxias no alto redshift com o ALMA.

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02/08 - 12:00 am BRT

Rogério Rosenfeld ( IFT-Unesp )

The Discovery of a New Boson at the LHC

In this talk I’ll describe how the long-sought Higgs boson of the Standard Model was finally found at the LHC.

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19/07 - 12:00 am BRT

Antônio Guimarães ( UFRJ )

Descrição (sem energia escura) da Expansão Cósmica

The apparent magnitude and redshift of type Ia supernovae provide currently the most stringent constraints on the cosmic expansion history. We study alternative ways to describe the cosmic expansion that are independent of dark energy models and even independent of assumptions about the energy contend of the universe and the underlying gravitational theory. One first approach was to use kinematic models for the cosmic expansion, where we found that even very simple models allow for data fittings that are as good as.

2011 16

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15/12 - 12:00 am BRT

Rogério Riffel ( -- )

From Porto Alegre to the world

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03/11 - 12:00 am BRT

Flavia Sobreira ( -- )

Angular correlation function as cosmological probes

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20/10 - 12:00 am BRT

Alexandre Andrei ( -- )

Tame as a pack of lions

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29/09 - 12:00 am BRT

Gustavo Porto de Mello ( -- )

Metallicities and Kinematics of Galactic Disk Stars from MARVELS Spectra

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15/09 - 12:00 am BRT

Júlio Camargo ( -- )

An astrometric contribution from the DECam observations

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01/09 - 12:00 am BRT

Letícia Dutra Ferreira ( -- )

The SDSS-III MARVELS survey: Exoplanets and Brown Dwarfs in late-type stars

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17/08 - 12:00 am BRT

Thiago Gonçalves ( -- )

O estudo de galáxias Lyman break em baixo redshift

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11/08 - 12:00 am BRT

Paulo Pellegrini ( -- )

Topics of Galaxy Evolution with Photometric Redshifts

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04/08 - 12:00 am BRT

Luciano Casarni ( -- )

High accuracy power spectra for non linear weak lensing forecasts

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09/06 - 12:00 am BRT

Ricardo Ogando ( -- )

The Cluster Finder Industrial Revolution

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02/06 - 12:00 am BRT

Cristina Furlanetto ( -- )

Arcos Gravitacionais em Aglomerados de Galáxias: detecção, caracterização e modelamento

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19/05 - 12:00 am BRT

Monica Benjamin ( -- )

Planning: scope and design documents

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12/05 - 12:00 am BRT

Leo Girard ( -- )

Attempts to fit TRILEGAL parameters using photometry from SDSS and 2MASS

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05/05 - 12:00 am BRT

Rogério Rosenfeld ( -- )

Forecasts for cosmological parameters from DES angular correlation function

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28/04 - 12:00 am BRT

Cristina Chiappini ( -- )

New constrains on Milky Way’s formation using TRILEGAL

Cristina Chiappini, Leo Girardi e João Amarante.

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14/04 - 12:00 am BRT

Helio Rocha-Pinto ( -- )

The Galaxy seen through finite lines of sight