Events at Physics
Events on Wednesday, October 26th, 2011
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- GRB Observations with Fermi Large Area Telescope
- Time: 2:30 pm
- Place: 4274 Chamberlin Hall
- Speaker: Vlasios Vasileiou, LUPM, Universite de Montpellier, Montpellier, France
- Abstract: During its first three years of operations, since August 2008, the Large Area Telescope on board the Fermi spacecraft (Fermi-LAT) has detected more than 30 GRBs in the ~30 MeV - 300 GeV energy range, and has set upper limits on the E>100 MeV emission on hundreds of GRBs occurring in its field of view. These results revealed new and puzzling features in the temporal and spectral behavior of GRBs, such as a delayed onset of the high-energy (E>100 MeV) emission with respect to the lower-energy (keV/MeV) signal detected by the Gamma-Ray Burst Monitor (Fermi-GBM), the presence of an extra spectral component in addition to the Band function, an extended emission lasting significantly longer than the lower-energy keV/MeV prompt emission, and the presence of spectral cutoffs at tens-of-MeV energies. We will present these discoveries and their theoretical implications, focusing both on individual cases and also in the context of a systematic and unbiased study performed towards the first Fermi-LAT GRB catalog. In addition, constraints on any energy dependence of the speed of light placed with GRB observations will be presented.
- Host: Segev BenZvi
- Astronomy Colloquium
- "Spectroscopic Support of Southern Photometric Surveys"
- Time: 3:30 pm
- Place: 4421 Sterling Hall
- Speaker: Mario Mateo, University of Michigan
- Abstract: he upcoming large-scale photometric surveys of the Southern Sky (SkyMapper, PanSTARRS, LSST, GAIA) promise to produce vast catalogs of interesting targets relevant to just about every area of modern astrophysics. I will describe a conceptual plan for a dedicated, all-sky spectroscopic survey that would powerfully complement these photometric projects. The focus of this plan is to develop a facility - the Southern Spectroscopic Survey Telescope (SSST) - that will provide highly flexible, wide-field and moderately deep spectroscopic capabilities over the entire Southern sky. The SSST's capabilities - all based on well-understood, proven technologies - allow it to efficiently explore a wide range of science projects. In particular, the SSST's ability to carry out a range of spectroscopic surveys simultaneously - each of which may involve targets with diverse field distributions and which require vastly different wavelength coverage and spectral resolution - will make it a uniquely powerful facility to advance a broad range of astronomical disciplines. I will describe how the science case for the SSST might be developed and implemented using, as preliminary examples, some specific science cases of interest to astronomers at the University of Michigan. I will also outline an approach that we have begun to pursue that aims to build a viable consortium -perhaps one spearheaded by the institutions of the Big-10? - that could build and operate the SSST through its initial survey cycles.
- Host: Professor Matt Bershady