Início » Ciência » Webinars » Apresentações » 2013
12/12 - 12:00 am
Martha Haynes
Abstract ⓘ
Abstract
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Martha Haynes
Title
The US Astronomy and Astrophysics Decadal Science Strategy Survey Process (Cornell University)
Abstract
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.
Slides not available
05/12 - 12:00 am
Luiz Nicolaci da Costa
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Luiz Nicolaci da Costa
Title
LIneA: Status Report (ON, LIneA)
Abstract
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.
Slides not available
28/11 - 12:00 am
Simon White
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Simon White
Title
The formation and evolution of the galaxy population (Max-Planck-Institut für Astrophysik)
Abstract
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.
Slides not available
14/11 - 12:00 am
Markus Demleitner
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Markus Demleitner
Title
The VO And Why It Matters To You (Heidelberg University)
Abstract
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.
Slides not available
07/11 - 12:00 am
Stephane Arnouts
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Stephane Arnouts
Title
The UV side of galaxy evolution (Laboratoire d’Astrophysique de Marseille)
Abstract
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.
Slides not available
24/10 - 12:00 am
Manda Banerji
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Manda Banerji
Title
The VISTA Hemisphere Survey (UCL)
Abstract
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.
Slides not available
17/10 - 12:00 am
Daniel Oliveira
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Daniel Oliveira
Title
Scientific Workflow Management in Cloud Environments (IC-UFF)
Abstract
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.
Slides not available
19/09 - 12:00 am
Richard Kron
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Richard Kron
Title
The Dark Energy Spectroscopic Instrument (DESI) (Fermilab)
Abstract
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.
Slides not available
12/09 - 12:00 am
Jean-Paul Kneib
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Jean-Paul Kneib
Title
Mapping the Universe with Massive Spectroscopic Redshift Surveys (Ecole polytechnique fédérale de Lausanne)
Abstract
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).
Slides not available
05/09 - 12:00 am
Stefan Müller
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Stefan Müller
Title
Dark Energy Survey – Software Management (FHNW)
Abstract
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.
Slides not available
29/08 - 12:00 am
Flávia Sobreira
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Flávia Sobreira
Title
Large-scale analysis of the Blind Cosmology Challenge Angular Correlation Function (Observatório Nacional)
Abstract
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.
Slides not available
22/08 - 12:00 am
Nelson Pinto
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Nelson Pinto
Title
Modelos cosmológicos sem singularidade e confronto com as observações (CBPF)
Abstract
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.
Slides not available
15/08 - 12:00 am
Marcos Lima
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Marcos Lima
Title
Cosmology from Galaxy Clusters (University of Sao Paulo)
Abstract
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.
Slides not available
08/08 - 12:00 am
Michael Blanton
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Michael Blanton
Title
The Future of the Sloan Digital Sky Survey (University of New York)
Abstract
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.
Slides not available
01/08 - 12:00 am
Rogério Rosenfeld
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Rogério Rosenfeld
Title
Some thoughts on the cross-correlation of cluster counts and ACF (IFT-UNESP)
Abstract
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.
Slides not available
18/07 - 12:00 am
Angelo Fausti
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Angelo Fausti
Title
Portal review, next developments and how you can contribute (LInea)
Abstract
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)
Slides not available
11/07 - 12:00 am
David Latham
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David Latham
Title
The Search for Habitable Planets (Havard University)
Abstract
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.
Slides not available
04/07 - 12:00 am
Kathy Romer
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Kathy Romer
Title
XMM Clusters through DECam Eyes (University of Sussex)
Abstract
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.
Slides not available
20/06 - 12:00 am
Alex Kim
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Alex Kim
Title
The Bright Future of Supernova Cosmology (Lawrence Berkeley National Laboratory)
Abstract
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.
Slides not available
13/06 - 12:00 am
Scott Dodelson
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Scott Dodelson
Title
Cross-Correlations (University of Chicago)
Abstract
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.
Slides not available
06/06 - 12:00 am
August Evrard
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August Evrard
Title
Synthetic Skies: a Brief Tour of Computational Cosmology (University of Michigan)
Abstract
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.
Slides not available
23/05 - 12:00 am
Diego Capozzi
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Diego Capozzi
Title
Constraining galaxy formation and its influence on the dark – baryonic matter relationship with future galaxy surveys (University of Portsmouth)
Abstract
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
Slides not available
16/05 - 12:00 am
Sarah Bridle
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Sarah Bridle
Title
Quantifying Dark Energy using Cosmic Lensing (University of Manchester)
Abstract
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.
Slides not available
09/05 - 12:00 am
Martin Crocce
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Martin Crocce
Title
Redshift Space Distortions from combined Photometric Samples (University of Barcelona)
Abstract
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.
Slides not available
02/05 - 12:00 am
Martin Groenewegen
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Martin Groenewegen
Title
The Herschel MESS program: an overview (Royal Observatory of Belgium)
Abstract
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.
Slides not available
25/04 - 12:00 am
Nikhil Padmanabhan
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Nikhil Padmanabhan
Title
Towards 1% measurements of cosmological distances with cosmic sound (Yale University)
Abstract
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.
Slides not available
18/04 - 12:00 am
Keivan Stassum
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Keivan Stassum
Title
Exoplanet discoveries, brown dwarfs, and fundamental stellar astrophysics from KELT, MARVELS, and Kepler (University of Vanderbilt)
Abstract
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.
Slides not available
21/03 - 12:00 am
Chris Miller
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Chris Miller
Title
Measuring the Masses of Galaxy Clusters using their Gravitational Potential (University of Michigan)
Abstract
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.
Slides not available
14/03 - 12:00 am
Ofer Lahav
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Ofer Lahav
Title
The benefits from combining imaging and spectroscopic surveys (University College London)
Abstract
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.
Slides not available
05/03 - 12:00 am
Joe Zuntz
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Joe Zuntz
Title
Cosmic Lensing with the Dark Energy Survey (University of Manchester)
Abstract
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.
Slides not available
28/02 - 12:00 am
Fábio Porto
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Fábio Porto
Title
Big Data Analysis in Astronomy (LNCC)
Abstract
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.
Slides not available