Bulletin of the American Physical Society
2009 APS April Meeting
Volume 54, Number 4
Saturday–Tuesday, May 2–5, 2009; Denver, Colorado
Session T4: Early Science from the Fermi Gamma-Ray Space Telescope |
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Sponsoring Units: DAP Chair: Steven Kahn, Stanford Linear Accelerator Center Room: Plaza F |
Monday, May 4, 2009 3:30PM - 4:06PM |
T4.00001: Fermi Observations of Gamma-Ray Bursts Invited Speaker: The Fermi Observatory is advancing knowledge of gamma-ray bursts by making pioneering observations at high energies. The Large Area Telescope (LAT) has unprecedented sensitivity for observations above about 20 MeV. The Gamma-Ray Burst Monitor (GBM) extends the energy range for GRBs from the LAT threshold down to about 8 keV. Both instruments have on-board software to detect and localize GRBs. The Observatory has the capability to autonomously reorient to maintain pointing at a GRB to search for extended high-energy emission. GBM has a trigger flux threshold of $\sim $0.7 photons/cm2/s and has detected over 100 GRBs in the first five months of operation. Several of these bursts have also been detected by the LAT. The high-energy observations provide new information on spectral variability and constraints on the Lorentz factor of the GRB fireball. [Preview Abstract] |
Monday, May 4, 2009 4:06PM - 4:42PM |
T4.00002: Fermi/LAT Observations of the Extragalactic Gamma-ray Sky Invited Speaker: The Fermi Gamma-ray Space Telescope provides a greatly expanded view of the extragalactic gamma-ray sky. The Large Area Telescope (LAT) aboard Fermi has more than an order-of-magnitude greater sensitivity than its predecessor, EGRET, and provides complete coverage of the sky every three hours. During the first year of operations, Fermi/LAT will detect up to several thousands of blazar AGNs and will produce valuable data on the flux and spectral variability of these objects on time scales ranging from several hours to months. The LAT energy range extends from 20 MeV to $>300$ GeV and thus overlaps with several ground-based Cherenkov telescopes. Coordinated observations with these instruments and with observatories at lower wavebands are playing an integral role in the scientific program of Fermi. Here we present several of the most interesting results from observing campaigns on individual blazars. We also present results from studies of the blazar population as a whole, relating the properties derived from Fermi data to those found at radio, optical, X-ray and TeV energies. The blazar contribution to the unresolved extragalactic diffuse emission and studies of other sources classes, such as galaxy clusters, will be discussed. [Preview Abstract] |
Monday, May 4, 2009 4:42PM - 5:18PM |
T4.00003: Galactic scientific results from the first 6 months of the Fermi/LAT mission Invited Speaker: The Large Area Telescope (LAT), one of two instruments on the Fermi Gamma-Ray Space Telescope (formerly GLAST, launched June 11, 2008) is a pair conversion detector designed to study the gamma-ray sky in the energy range 20 MeV to >300 GeV. The greatly improved sensitivity of the LAT compared with its predecessor experiment, EGRET on the Compton Gamma-Ray Observatory, coupled with the uniform and deep sky coverage, and lack of consumables, provides a unique capability for studying the gamma-ray Universe. The Galaxy is replete with gamma-ray sources: pulsars, X-ray binaries, supernova remnants, and molecular clouds to name a few. The propagation of cosmic rays in the Galaxy produces diffuse gamma-ray emission through interactions with the interstellar gas and radiation fields, and is the bright background against which the sources are detected. Diffuse gamma-ray emission is also expected from similar processes in nearby galaxies, such as the Large Magellanic Cloud (which was detected by EGRET), and even from within the solar system itself. The LAT has detected many Galactic gamma-ray sources and the diffuse emissions of the Milky Way and some Local Group galaxies with unprecedented sensitivity and resolution. I will give an overview of the results obtained on these topics for the first 6 months of the Fermi/LAT mission. [Preview Abstract] |
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