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 227

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Scheduled webinars

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25/04 - 11:00 am BRT

Bruno Castilho ( LNA )

Title: to be Announced

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16/05 - 11:00 am BRT

Katelyn Stringer ( Texas A&M University )

Identifying RR Lyrae in the Dark Energy Survey

RR Lyrae variable stars (RRL) are powerful distance indicators which can be used to locate stellar structures within the Milky Way halo. The Dark Energy Survey (DES), with its large observing footprint and depth, presents a rich opportunity to discover these variables to distances near the edge of the Galactic halo. However, the small number of observations in the DES wide-field survey data (fewer than 20 multiband observations over the first three years) pose a challenge for the traditional RRL detection techniques. In this talk, I will describe the multiband template fitting method and machine learning classifier we developed to identify 5783 RRL candidates in the first three years of DES data. These methods will enable RRL detection in other sparse multiband data sets that are not optimized for time series analyses.

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23/05 - 11:30 am BRT

Fabian Schmidt ( Max Planck Institute - Garching )

New approaches to galaxy clustering

The large-scale clustering of galaxies contains a wealth of information on the geometry and expansion history of the universe, on gravity, and on the initial conditions. In order to extract this information, we need to deal with the complex formation process of galaxies. As a result, current observational constraints are largely based only on the robust BAO feature. However, thanks to significant advances in o ur theoretical understanding of galaxy clustering, we now have a well-defined approach for absorbing all the complicated, incompletely understood physics of galaxy formation into a set of free parameters (the bias parameters and stochastic amplitudes), which opens up considerable additional constraining power. The next challenge to tackle then is how best to connect this theory with data, as delivered by ongoing and future surveys such as BOSS, DESI, and Euclid. In my talk, I will review these developments, and discuss the prospects galaxy clustering as a robust probe of cosmology in the coming decade.

Past webinars


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18/04 - 11:00 am BRT

Paola Dimauro ( Observatoire de Paris )

Is morphology telling us the truth about quenching?

Passive and star forming galaxies have different morphology and structure, suggesting a link between the star formation activity and the formation/growth of internal components. Despite the numerous efforts, the details of how galaxies form and evolve, and in particular the mechanisms responsible of the decreasing/cessation of the star formation and the morphological transformations are still not fully understood. In the talk I will present results we obtained combining the morphology and the star formation activities for galaxies in the CANDELS survey. We first studied structural properties of the four main morphological classes (bulge dominated systems, pure spiral disk dominated, intermediate 2-component and irregular disturbed galaxies) and how their fractions change at different epochs (Huertas-Company et al,2016) to then move forward and analyze in more details the galaxy structure exploring bulge and disk properties and how they correlate with the morphology or the star formation activities of the host galaxies (Dimauro et al, 2018, 2019).

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11/04 - 11:00 am BRT

Hao-Yi Wu ( The Ohio State University )

Probing Cosmic Acceleration with Galaxy Clusters

The acceleration of the Universe is one of the biggest puzzles in physics: is it due to a cosmological constant, dynamical dark energy, or modification of gravity? Galaxy clusters provide a unique opportunity to answer this question. In this talk, I will first discuss how we use cluster abundances to constrain cosmic acceleration, and how weak gravitational lensing effects play a key role in constraining cluster mass. I will then present my research on using simulations to understand cluster weak lensing signals and to accurately model covariance matrices. These results not only mitigate the systematic errors in current cluster surveys but also help the optimization of future ground- and space-based missions.

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04/04 - 11:00 am BRT

Adriano Pieres ( LineA )

Describing the thick disk and halo of the Galaxy as seen by the Dark Energy Survey

In this webinar I will talk about the results of the MWFitting pipeline applied to the stellar content of the DES-Y3 Gold internal release, in a paper about to be published. We fit the thick disk and halo of the Milky Way, simulating the Galaxy with a combination of TRILEGAL models. The stellar density of the thick disk is modeled with an exponential dependence in the radial and vertical directions, and the halo is described as an oblate model with the density of stars decreasing following a radial power law. The pipeline shows robust parameters for those components and the residuals from photometric comparisons attest the excellent job of the method. I detailed the methods applied in the pipeline, the implications of the results, also regarding the upcoming surveys and finally preliminary outcomes with other surveys.

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28/03 - 11:00 am BRT

Jennifer Marshall ( Texas University )

The future of massively multiplexed spectroscopy: the Maunakea Spectroscopic Explorer

Numerous international astronomy reports have recently highlighted the need for fully dedicated, large aperture, massively multiplexed spectroscopy in the optical and near-Infrared wavelength regimes. Such a facility is the most obvious missing link in the emerging network of ground-based observational facilities world-wide. The Maunakea Spectroscopic Explorer (MSE) is a planned 11-m telescope facility designed to fill this scientific gap. MSE is completely dedicated to multi-object optical and near-Infrared spectroscopy of samples of between thousands and millions of astrophysical objects at a range of spectral resolutions. In this talk I will overview the wide-ranging scientific capabilities of the MSE project and review the current design status of this next generation observatory.

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21/03 - 11:00 am BRT

Michael Wood-Vasey ( University of Pittsburgh )

LSST and Data Facilities to Enable Science with Billions of Objects

The Large Synoptic Survey Telescope will open new frontiers in large-scale data analysis in astronomy. In this talk I will discus the opportunities and current implementation of data access and analysis in the LSST Project and in the Dark Energy Science Collaboration. The LSST Science Platform is being built to enable the LSST community to explore the rich and large datasets from from LSST. While the LSP may not be fully operational until the beginning of the LSST Operations in late 2022, development and prototyping efforts are currently underway to understand both the technical scope and user interactions with this ambitious platform. In parallel to the LSST Project construction efforts, the wider LSST scientific community is preparing for LSST. In particular, the Dark Energy Science Collaboration (DESC) was formed to fully exploit the ability of LSST to determine the nature of dark energy. In advance of data from LSST, DESC is preparing a series of Data Challenges to develop and verify scientific and basic data processing pipelines. These data challenges are helping both DESC and the LSST Project explore and understand the opportunities and challenges of exploring terabyte-scale image datasets with catalogs with billions to trillions of entries.

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14/03 - 11:00 am BRT

Brian Yanny ( Fermilab )

The Balrog simulation for DES Years 1-3

We present details of the Balrog object injection and (re)measurement code which is used by DES to determine completeness and biases in detection and measurement of faint stars and galaxies.

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07/03 - 11:00 am BRT

George Beckett ( University of Edinburgh )

UK Ambitions for Astronomy in the LSST Era

The Large Synoptic Survey Telescope promises to revolutionalise many aspects of optical astronomy, most notably dealing with the transient universe. UK-based astronomers have a particular opportunity, since the UK is part of several other significant facilities on a similar timescale--for example, Euclid, 4MOST, and SKA--yielding a possibility to secure leadership in a number of areas, including dark energy, solar system science, and transients. Recognising this, the UK community has formed a consortium with representation from every UK-based astronomy group, to encapsulate its ambitious plans for LSST and to secure funding for a substantial programme of R&D, in the lead up to the beginning of telescope operations in 2022. Through this consortium, LSST:UK has secured data rights for 100 Affiliate PIs (plus the associated 400 Junior Associates), and embarked on an 8-year research and development programme that will yield a UK-based LSST Data Access Centre, tailored to the specific requirements of priority UK astronomy goals. In this talk, I will share highlights from the UK programme to date, including an alert-handling service that is being trialled on the Zwicky Transient Facility, large-scale database ingest and query experiments, toward the 35 billion objects that LSST is predicted to observe, and a fledgling cloud-based deployment of an analysis platform that will be at the heart of the UK DAC. I will also preview the plans for the next phase of work, during 2019--2023, which are likely to involve closer international collaboration on provisioning of data and associated analysis services as well as the finalisation of plans for UK-led User-generated Products, as we transition from the construction to the commissioning phase of LSST.