Início » Ciência » Webinars » Apresentações » 2014
11/12 - 10:00 am
Luiz Nicolaci da Costa
Abstract ⓘ
Abstract
×Speaker
Luiz Nicolaci da Costa
Title
Reviewing 2014 and Outlook for 2015 (ON/LIneA)
Abstract
Slides not available
27/11 - 10:00 am
Hendrik Hildebrandt
Abstract ⓘ
Abstract
×Speaker
Hendrik Hildebrandt
Title
PHAT: PHoto-z Accuracy Testing (Bonn University)
Abstract
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.
Slides not available
13/11 - 01:30 pm
David Gerdes
Abstract ⓘ
Abstract
×Speaker
David Gerdes
Title
Characterizing the trans-Neptunian Solar System with DES (University of Michigan)
Abstract
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.
Slides not available
07/11 - 12:00 am
Stephane Arnouts
Abstract ⓘ
Abstract
×Speaker
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
06/11 - 12:00 am
Ben Burningham
Abstract ⓘ
Abstract
×Speaker
Ben Burningham
Title
Testing substellar atmospheric models with benchmark brown dwarfs (University of Hertfordshire/NASA Ames)
Abstract
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.
Slides not available
30/10 - 10:00 am
Beth Willman
Abstract ⓘ
Abstract
×Speaker
Beth Willman
Title
Observational cosmology in the Milky Way’s backyard (Havefroth College)
Abstract
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.
Slides not available
09/10 - 11:00 am
Jeffrey Kantor
Abstract ⓘ
Abstract
×Speaker
Jeffrey Kantor
Title
Future Wide Field Imaging with LSST (LSST)
Abstract
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.
Slides not available
02/10 - 10:00 am
Maria Teresa Crosta
Abstract ⓘ
Abstract
×Speaker
Maria Teresa Crosta
Title
Gravitational Astrometry in the Gaia Era (Observatorio Astrofisico di Torino)
Abstract
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.
Slides not available
25/09 - 02:00 pm
Eduardo Rozo
Abstract ⓘ
Abstract
×Speaker
Eduardo Rozo
Title
Planck Clusters and Neutrino Mass (Stanford)
Abstract
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.
Slides not available
18/09 - 11:00 am
Michael Strauss
Abstract ⓘ
Abstract
×Speaker
Michael Strauss
Title
The Evolution of Quasars with Cosmic Time (Princeton University)
Abstract
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.
Slides not available
11/09 - 10:00 am
Stefano Borgani
Abstract ⓘ
Abstract
×Speaker
Stefano Borgani
Title
Cosmology with galaxy clusters: the role of simulations (OATS/INAF)
Abstract
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.
Slides not available
04/09 - 02:00 pm
Enrique Gaztañaga
Abstract ⓘ
Abstract
×Speaker
Enrique Gaztañaga
Title
LSS with angular cross-correlations:Combining Spectroscopic and Photometric Surveys (IEEC-CSIC)
Abstract
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.
Slides not available
28/08 - 11:00 am
Basilio Santiago
Abstract ⓘ
Abstract
×Speaker
Basilio Santiago
Title
Resolved Stellar Populations: DES and beyond (UFRGS)
Abstract
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.
Slides not available
21/08 - 11:00 am
Jo Bovy
Abstract ⓘ
Abstract
×Speaker
Jo Bovy
Title
Unraveling the Milky Way’s history with APOGEE (Princeton University)
Abstract
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.
Slides not available
14/08 - 11:00 am
Luciano Nicastro
Abstract ⓘ
Abstract
×Speaker
Luciano Nicastro
Title
Databases and web technologies for astronomy (INAF – IASF Bologna)
Abstract
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.
Slides not available
07/08 - 02:00 pm
Jeff Newman
Abstract ⓘ
Abstract
×Speaker
Jeff Newman
Title
Exploring the Milky Way and the Universe with Extragalactic Surveys (University of Pittsburgh)
Abstract
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.
Slides not available
31/07 - 11:00 am
Boris Leistedt
Abstract ⓘ
Abstract
×Speaker
Boris Leistedt
Title
Constraints on Primordial non-Gaussianity from 800,000 photometric quasars (UCL)
Abstract
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.
Slides not available
24/07 - 11:00 am
Jim Annis
Abstract ⓘ
Abstract
×Speaker
Jim Annis
Title
The DES and gravity wave counterpart detections (Fermilab)
Abstract
Slides not available
26/06 - 11:00 am
Mario Mateo
Abstract ⓘ
Abstract
×Speaker
Mario Mateo
Title
The Present and Future(?) of Multi-Object Fiber Spectroscopy (University of Michighan)
Abstract
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.
Slides not available
05/06 - 11:00 am
Felipe Braga Ribas
Abstract ⓘ
Abstract
×Speaker
Felipe Braga Ribas
Title
A ring system detected around the Centaur (10199) Chariklo – Parte II (Observatório Nacional)
Abstract
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.
Slides not available
29/05 - 02:00 pm
Steven Kahn
Abstract ⓘ
Abstract
×Speaker
Steven Kahn
Title
LSST science overview (Standford University)
Abstract
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.
Slides not available
08/05 - 11:00 am
Matias Carrasco Kind
Abstract ⓘ
Abstract
×Speaker
Matias Carrasco Kind
Title
How to produce, combine, store and use photo-z PDFs (UIUC)
Abstract
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.
Slides not available
24/04 - 10:00 am
Marla Geha
Abstract ⓘ
Abstract
×Speaker
Marla Geha
Title
The Baryon Content of Ultra-Faint Galaxies (Yale University)
Abstract
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.
Slides not available
17/04 - 10:00 am
Jim Rich
Abstract ⓘ
Abstract
×Speaker
Jim Rich
Title
Dimensional Analysis in Cosmology (SPP – Saclay)
Abstract
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.
Slides not available
10/04 - 10:00 am
Felipe Braga Ribas
Abstract ⓘ
Abstract
×Speaker
Felipe Braga Ribas
Title
A ring system detected around the Centaur (10199) Chariklo – Parte I (Observatório Nacional)
Abstract
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.
Slides not available
03/04 - 12:00 pm
Mario Juric
Abstract ⓘ
Abstract
×Speaker
Mario Juric
Title
LSST Data Management: Overview of the System (LSST)
Abstract
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.
Slides not available
27/03 - 10:00 am
Roderik Overzier
Abstract ⓘ
Abstract
×Speaker
Roderik Overzier
Title
The Formation of Cosmic Structure through the eyes of new Surveys and Simulations (Observatório Nacional)
Abstract
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.
Slides not available
20/03 - 12:00 am
Kevin Bundy
Abstract ⓘ
Abstract
×Speaker
Kevin Bundy
Title
The Manga Instrument and Survey (IPMU/University of Tokyo)
Abstract
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.
Slides not available
13/03 - 10:00 am
Patrick Petitjean
Abstract ⓘ
Abstract
×Speaker
Patrick Petitjean
Title
Quasar Science from SDSS (Institut d’AstroPhysique)
Abstract
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.
Slides not available
27/02 - 04:00 pm
Ani Thakar
Abstract ⓘ
Abstract
×Speaker
Ani Thakar
Title
SkyServer to SciServer: The Past, Present and Future of the SDSS CAS (Johns Hopkins University)
Abstract
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.
Slides not available
20/02 - 11:00 am
Daniel Eisenstein
Abstract ⓘ
Abstract
×Speaker
Daniel Eisenstein
Title
The Dark Energy Spectroscopic Instrument (Harvard University)
Abstract
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.
Slides not available
17/02 - 10:00 am
Tsvi Piran
Abstract ⓘ
Abstract
×Speaker
Tsvi Piran
Title
Neutron star mergers, Gamma-Ray Bursts and the Origin of Gold (Racah Institute of Physics, Hebrew University of J)
Abstract
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.
Slides not available
06/02 - 12:00 am
Daniel Thomas
Abstract ⓘ
Abstract
×Speaker
Daniel Thomas
Title
Science with SDSS-IV/MaNGA (University of Portsmouth)
Abstract
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.
Slides not available
30/01 - 12:00 am
David Weinberg
Abstract ⓘ
Abstract
×Speaker
David Weinberg
Title
Cosmological Highlights from the Sloan Digital Sky Survey (Ohio State University)
Abstract
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.
Slides not available
22/01 - 12:00 am
Nicolás G. Busca
Abstract ⓘ
Abstract
×Speaker
Nicolás G. Busca
Title
First observations of Baryon Acoustic Oscillations in the LyA forests of BOSS quasars (ON/LIneA)
Abstract
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.
Slides not available