Webinars 330

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 300

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Scheduled webinars 01

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29/07 - 11:00 am BRT

Jacques Lepine ( Universidade de São Paulo )

The role of the co-rotation resonance in the Galactic disk and its influence on the Sun and stars of the Solar neighborhood

Past webinars 329

2021

20
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22/07 - 11:00 am BRT

Carlos Bengaly ( (Observatório Nacional) )

Observational tests of the fundamental hypothesis of Cosmology

The standard model of Cosmology (SCM) consists on the LCDM model, which is dominated by cold dark matter and Cosmological Constant. Although this model provides the best description of cosmological observation thus far, the nature of these two components remain unveiled. Therefore, there is an urge to develop models to explain them, but on top of that, we need to put the fundamental hypotheses underlying the SCM under scrutiny. After all, statistically significant evidence of departure of these hypotheses may lead to complete reformulation of the SCM. In this talk, I present some observational tests I carried out with this goal. I will talk about some observational tests of the Cosmological Principle - namely, the assumption of large-scale homogeneity and isotropy of the Universe - using a variety of cosmological data. In addition, I will show results obtained by probing the validity of two fundamental assumptions which these data relies upon: the constancy of the absolute magnitude of Type Ia Supernovae, and the current temperature of the CMB.

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15/07 - 11:00 am BRT

Davide Perna ( INAF Rome Astronomical Observatory )

Near-Earth Asteroids: Risks and Opportunities

The proximity of near-Earth asteroids (NEAs) allows us to investigate the physical properties of small bodies down to the decameter-scale. A dedicated space mission to such small NEAs will be key to shed light on accretion mechanisms that took place in the protoplanetary disk. Extended ground-based observations will be also fundamental to fully characterize the physical diversity of the NEA population, whose discovery rate is exponentially growing in recent years. Besides its relevance for our understanding of the solar system and planetary science, NEA investigation is also essential to assess the potential exploitation of the asteroidal mineral resources in the near future, as well as to increase our capacity of mitigating the asteroid threat of collision with the Earth. I will present and discuss some recent results and future perspectives related to the science of NEAs, with a particular focus on small-sized objects.

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08/07 - 11:00 am BRT

Denny Lee ( Databricks )

Bringing Reliability to your Data Lake with Apache Spark and Delta Lake

Apache Spark has become the de-facto open-source standard for big data processing for its ease of use and performance. The open-source Delta Lake project improves Spark’s data reliability, with new capabilities like ACID transactions, Schema Enforcement, and Time Travel. This helps to ensure that data lakes and data pipelines can deliver high-quality and reliable data to downstream data teams for successful data analytics and machine learning projects. Join us to learn how Apache Spark 3.0 and Delta Lake enhance Data Lake reliability.

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01/07 - 02:00 pm BRT

Wagner Corradi ( Universidade Federal de Minas Gerais / LNA )

Impacto da ciência realizada com os telescópios e instrumentos gerenciados pelo LNA

O Laboratório Nacional de Astrofísica (LNA) é a Unidade de Pesquisa do Ministério de Ciência, Tecnologia e Inovação (MCTI) responsável por planejar, desenvolver, promover, operar e coordenar os meios e a infraestrutura para fomentar, de forma cooperada, a Astronomia Observacional Brasileira. O LNA possui a importante tarefa de gerenciar o Observatório do Pico dos Dias (OPD) e a participação brasileira nos observatórios internacionais Gemini (Norte, no Havaí e Sul, no Chile) e SOAR, no Chile, além de outras iniciativas como o PanEOS, LSST e LLAMA, por exemplo. Além disso, participa ativamente na concepção e construção de novos instrumentos astronômicos e sistemas periféricos. Pretendemos apresentar os avanços na instrumentação e o impacto da ciência realizada com os telescópios gerenciados pelo LNA, a partir de uma perspectiva histórica, nesses 35 anos de sua existência.

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24/06 - 09:00 am BRT

Dalya Baron ( Tel Aviv University )

Machine learning in astronomy: past, present, and future

Machine Learning and Deep Learning have revolutionized many domains, and have sparked a burst of interest in astronomy as well. Astronomical datasets, being large, rich, and consisting of the beautifully complex ingredients of our Universe, seem to offer the perfect testbed for such tools. Past, ongoing, and future surveys have provided or are expected to provide multi-color and multi-temporal observations of hundreds of millions of stars and galaxies in our Universe. The application of Machine Learning tools to these datasets may offer new and exciting opportunities, but it also raises several questions. Will Machine Learning revolutionize the field of astronomy as well? Will it have a dramatic impact on our data processing pipelines, on the models we deduce from the data, or on the types of scientific questions that we ask? In this talk I will review different types of Machine Learning algorithms and will present some example applications of these tools to astronomical datasets. I will describe the current state of the field, focusing on the challenges we face. I will finish by proposing an approach that might help us harness the full potential of these tools in the future.

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10/06 - 02:00 pm BRT

Robert Nikutta ( NOIRLab )

Astro Data Lab - An open-access and open-data science platform

The Astro Data Lab (https://datalab.noirlab.edu), or Data Lab for short, is an astronomical science platform developed at NOIRLab. It is open and free to all who are interested in astronomy, data science, and education efforts. Launched 4 years ago to enable remote access and analysis of survey data products generated by NOAO\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\'s telescopes, such as the Dark Energy Survey, Data Lab now serves almost 100 TB of catalog data from all major NOIRLab-operated facilities, plus high-value external datasets (e.g. Gaia, unWISE/AllWISE, SDSS, and others). It also provides access to over 2 PB of images. As a science platform Data Lab combines big data holdings with a number of very useful data services, and with the powerful idea of remote analysis through a Jupyter notebook server. Data Lab user accounts come with a generous allocation of remote storage for files and personal databases. In this seminar I will introduce the concepts that underlie a science platform, and highlight the data services Data Lab is able to offer thanks to the co-location of big data and compute capacities. I will then discuss some of our current new developments, for instance to serve data products from massively-multiplexed spectroscopic surveys such as SDSS and DESI. Finally I would also like to discuss with everybody some of the challenges and pportunities for making science platforms more unified in terms of user experience, and more interoperable from the operators\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\' perspective. Time permitting, I can show a brief live demo of Data Lab.

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03/06 - 12:00 am BRT

Public Holiday ( Corpus Christi )

No event scheduled

On that day there will be no LIneA webinar. Corpus Christi is a public holiday in some countries, including Brazil.

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27/05 - 11:00 am BRT

Willian Vieira de Abreu ( Universidade Federal do Rio de Janeiro )

Divulgação científica na astronomia: experiências e perspectivas

A Astronomia e ciências afins despertam o interesse da população, oferecendo um grande potencial de estimular jovens a ingressarem em carreiras científicas e despertarem o interesse por temáticas relacionadas. Dentro desse contexto, a divulgação científica pode exercer um importante e necessário papel de impulsionadora de novos talentos e de facilitadora entre ciência e sociedade, podendo inclusive possibilitar um primeiro contato com as ferramentas técnicas da área. Mas o que os jovens pensam sobre a ciência? E os comunicadores da ciência: o que pensam e pesquisam? Discutiremos essas e outras questões a partir de estudos acadêmicos e de dados do Instituto Nacional de Comunicação Pública da Ciência (INCT-CPCT), bem como de pesquisas nacionais e internacionais.

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20/05 - 11:00 am BRT

Thaisa Storchi Bergmann ( Universidade Federal do Rio Grande do Sul )

The relation between Supermassive Black Holes and their host galaxies probed by the MaNGA-SDSS survey

Supermassive Black Holes (SMBHs, masses of 106 – 109 MSun) inhabit the nucleus of most galaxies in the Universe. Although not even light can escape their event horizon, when capturing mass, they become the most efficient energy generators in the Universe via the emission of radiation, winds and jets by an accretion disk that surrounds them in active galactic nuclei (AGN). These are the so-called AGN feedback processes required by galaxy evolution models in order to reproduce the mass distribution of galaxies in the Universe. Nevertheless, the actual processes involved are not yet well constrained by observations. In this talk, I will discuss studies that provide constraints to these processes via MaNGA-SDSS observations of a sample of AGN and a matched control sample of non-active galaxies. These observations have been used to investigate answers to two of the most important questions on the relation between SMBHs and their host galaxies: (I) What are the necessary conditions for triggering/maintaining AGN in galaxies? (II) Which is the impact of the nuclear activity on the host galaxy and its environment?

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13/05 - 11:00 am BRT

Francesco Valentino ( University of Copenhagen )

The life and death of massive galaxies

The majority of the stars in the local Universe belong to massive, red, spheroidal, old galaxies that died several billion years ago, ceasing their active formation of new stars. In our current view, these galaxies experienced an intense burst of growth immediately followed by a sudden death early in the history of the Universe, so that we routinely observe a numerous population of such dead cosmic giants already in place 10 Gyr ago at z~2 comfortably reproduced by many galaxy formation models and simulations. However, the coherent scenario that we have been building during the last 15 years has been recently shaken by the discovery of the existence of massive dead galaxies already at z~4, only 1.5 Gyr after the Big Bang. How is it possible to assemble 100 billion Suns in such a short time, given the expected theoretical limits on the sustainable star formation rate? What can we learn about such a dramatic production of stars? What are the progenitors of these quiescent galaxies at z>4? And why do these cosmic giants die so early in the history of the Universe? Here I will present the results of a spectroscopic campaign targeting massive quiescent galaxies at z~4. These include a compact system at z=4.01 with a measured stellar velocity dispersion fully consistent with z~2 objects, showing that quiescent galaxies can be remarkably mature also from a dynamical standpoint. The absence of nebular emission lines and the lack of far-infrared detections confirm a suppressed star formation. From the joint modeling of the spectra and the SEDs, we derive stellar masses of log(Mstar/Msun)~11, placing these galaxies >1-2 dex below the main sequence. Such modeling suggests that these sources experienced a strong (SFR~1200-3500 Msun/yr) and short (~50 Myr) burst of star formation in their past, properties reminiscent of the population of sub-mm galaxies (SMGs) generally indicated as candidate progenitors. We thus compare the comoving number densities and the expected properties of the progenitors of our and other samples in the literature with observations of z>4 SMGs. We find a fair agreement between these two populations only for the deepest sub-mm surveys detecting the most extreme starbursts, but also more normal galaxies. Exploring the Illustris-TNG simulation, we do retrieve populations of quiescent galaxies at z~3-3.5 with number densities and properties in rough agreement with the observations, but in increasing tension at higher redshifts. We find that not all the progenitors of z~4 quiescent galaxies in the simulation shine as bright SMGs in their past and, conversely, not all bright SMGs quench by z~3, supporting the observational evidence and suggesting the existence of different paths to form massive galaxies in the early Universe.

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07/05 - 03:00 pm BRT

Michael Blanton ( University of New York )

Galaxies Near and Far with the Sloan Digital Sky Survey

I will discuss the recent work of the Sloan Digital Sky Survey on cosmology and galaxy evolution, based on the observations from its fourth phase, which completed its six year program on the morning of January 21, 2021. This spectroscopic survey mapped the Milky Way galaxy, ten thousand nearby galaxies, and finished the largest three-dimensional map of the universe to date. I will describe a sampling of what we have learned, focusing on: tests of the \\\\\\\"simplest\\\\\\\" model of the universe\\\\\\\'s expansion (which seems to be the right one); observations of star-formation and the flow of gas within galaxies; and on the formation history and migration of stars within our own galaxy.

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29/04 - 02:00 pm BRT

Samuel Schmidt ( University of California Davis )

Rubin Obs. Dark Energy Science Collaboration Photometric Redshifts: Challenges and Opportunities

In the era of large area, deep imaging surveys the ability to follow up even a small fraction of objects with spectroscopy is prohibitively expensive. As a result, these surveys will need to rely on other means to determine the distance to objects and turn the observed 2D sky into a fully three-dimensional map of the Universe using only the limited information available from broad band fluxes. In this talk I will discuss the challenges inherent in estimating redshifts for cosmology measurements in the Rubin Observatory Dark Energy Science Collaboration (DESC), which has extremely stringent requirements on knowledge of both individual galaxy redshifts and the redshift distribution of ensemble collections. I will discuss the end-to-end photometric redshift pipeline being developed by DESC, from simulated catalogs, to template and machine learning-based estimation algorithms, to systematic calibrations, that will enable the cutting edge science of the coming decade.

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22/04 - 11:00 am BRT

Allan Alves & Denise Köche ( Agência Propósito )

O que pensa e o que busca a comunidade científica na chegada do LSST

No webinar, a empresa de comunicação Propósito dividirá aprendizados sobre a pesquisa e os workshops realizados com a comunidade científica junto ao LIneA durante o mês de Março de 2021, com as percepções em relação aos impactos e expectativas do uso de big data na astronomia brasileira, assim como as barreiras e expectativas para o futuro.

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15/04 - 11:00 am BRT

LIneA Workshop ( LIneA )

On the Future of Data Centers and eScience Institutes: Celebrating LIneA’s 10th Anniversary

This workshop will bring together representatives of some of the more important data centers, eScience institutes and IT companies to discuss current solutions and new technological trends as data volumes from modern experiments such as LSST, Euclid and SKA continue to grow. The workshop will take place remotely April 13-15, 2021. Inquiries can be sent to workshop2021@linea.gov.br.

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08/04 - 11:00 am BRT

Santiago Àvila ( Universidad Autónoma de Madrid )

The effect of the galaxy-halo connection on galaxy clustering in the advent of stage-IV experiments

Studies of the Large-Scale Structure via galaxy clustering is a fundamental observational pillar of the standard model of cosmology, LCDM. As we enter the era of sub-percent precision cosmology, we need to understand very well the connection between the dark matter halos and the observed galaxies ir order to obtain unbiased cosmological parameters. In this talk I will analyse all the assumptions that enter into the Halo Occupation Distribution (HOD) model to understand how they can affect the clustering of galaxies, with a focus on Emission Line Galaxies (ELGs), key to the next generation of experiments. I will study the shape of the mean halo occupation curves, the probability distribution function of the satellite galaxies and the position and velocity profiles of the satellite galaxies around the halo centers. Later, I will fit the HOD model to ELG data from the completed extended Baryonic Oscillation Spectroscopic Survey (eBOSS) under different assumptions. Finally, I will show what effect the galaxy-halo connection could have on cosmological constraints and will discuss its relevance in the context of future surveys such as Euclid or DESI.

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01/04 - 11:00 am BRT

Tilman Troester ( Royal Observatory, Edinburgh )

Cosmology with the Kilo-Degree Survey

I will present the recent cosmological analyses of weak gravitational lensing observations from the Kilo-Degree Survey (KiDS-1000), with redshift-space galaxy clustering observations from the Baryon Oscillation Spectroscopic Survey (BOSS), and galaxy-galaxy lensing observations from the overlap between KiDS-1000, BOSS and the spectroscopic 2-degree Field Lensing Survey (2dFLenS). I will summarise the methodology and discuss the cosmological constraints, both within the the standard model of cosmology of a spatially flat Universe filled with cold dark matter and dark energy, and several extensions thereof. These results are then put in the context of the S8 tension: the disagreement between measurements of the cosmic microwave background by Planck and late-time analyses, such as ours, on how strongly matter in the Universe is clustered.

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25/03 - 04:00 pm BRT

David Latham ( Harvard-Smithsonian Center for Astrophysics )

TESS - Transiting Exoplanet Survey Satellite

NASA’s Transiting Exoplanet Survey Satellite finished its primary mission and started its first extended mission on July Fourth, 2020. I will trace the history of the mission and the lessons we learned from Kepler and K2, ending with some of the recent highlights.

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18/03 - 11:00 am BRT

Eduardo Janot Pacheco ( Universidade São Paulo )

The PLATO mission: Brazil chasing exoplanets

PLATO is a medium-class mission of ESA’s Cosmic Vision Program. It will address fundamental questions such as: How do planetary systems form and evolve? Are there other systems with planets like ours, able to develop life? The PLATO instrument consists of 26 small aperture telescopes providing a wide field-of-view and a large photometric magnitude range. It will target bright stars in wide fields to detect and characterize by photometric transit planets in the Habitable Zone down to Earth-size. Asteroseismology will be performed for the host stars to obtain unprecedentedly accurate stellar parameters, including masses and ages. Planet parameters accuracy are intended to be: 2%, 4-10% and 10% for planet radii, masses and ages, respectively. Up to 1,000,000 stars in about 50% of the sky will be observed and hundreds of small planets and thousands of Neptune to gas giants will be characterized, providing the first large-scale catalogue of bulk characterized planets with accurate parameters. The data will allow for the first time robust statistical analysis on physical characteristics of planets, of planetary formation, migration, architecture and evolution and its dependence on spectral type, metallicity and age of the host stars. Thirteen European countries and Brazil are participating in PLATO construction and scientific planning. Brazilian scientists of universities and research centers from all over the country are participating in the preparation of the PLATO mission. We will explore the satellite’s data mainly in the fields of stellar seismology, variable stars, white dwarfs, stellar rotation and exoplanets. Brazilian engineering is developing hardware and software components: a simulator for testing the image reading front-end electronics, photometric masks for imaging extraction, part of the altitude control system and jitter correction. We will give in this talk an overview of the PLATO mission and of the Brazilian participation.

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11/03 - 11:00 am BRT

Sunil Mucesh ( University College London )

A machine learning approach to galaxy properties: Joint redshift-stellar mass PDFs with Random Forest

Point estimates of galaxy properties determined with a small number of photometric bands are imprecise. To fully characterise uncertainties in the estimates, accurate probability distribution functions (PDFs) are required. These PDFs must also reflect the correlations between different quantities of interest. Traditionally, such PDFs are derived by fitting model spectra to photometric data. However, this approach quickly becomes impractical for fitting modern datasets, where sample numbers can exceed hundreds of millions. In this talk, I present a novel method based on the Random Forest (RF) machine-learning (ML) algorithm to generate accurate joint redshift-stellar mass PDFs. I discuss different techniques used to validate both the marginal and joint PDFs. Finally, I demonstrate GALPRO, a Python package capable of producing multivariate PDFs of galaxy properties on-the-fly at incredible speeds, and discuss some of its applications.

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04/03 - 01:00 pm BRT

Leanne Guy ( Vera Rubin Observatory )

Opportunities for Early Science with Rubin/LSST

Starting in 2023, the Vera C. Rubin Observatory will spend its first 10 years conducting the Legacy Survey of Space and Time (LSST). LSST will observe the entire visible southern sky and provide the widest, fastest and deepest view of the night sky ever observed. The resulting astronomical archive will be vast; 500PB of image data products and a 15PB final catalog of ~ 40 billion Objects. LSST will dramatically advance our knowledge in many fields including dark energy and dark matter, as well as galaxy formation and potentially hazardous asteroids. In this talk I give an overview of the Rubin Observatory and the Legacy Survey of Space and Time and talk about opportunities for early science and how to get involved.

2020

41

2019

36

2018

38

2017

30

2016

34

2015

31

2014

35

2013

31

2012

17

2011

16