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March 1 (4:00PM) in the 2nd Floor Conference Room in Dearborn Speaker: Vaso Pavlidou (KICP - Univ of Chicago) “Deciphering the GeV Sky: Gamma-Ray Astronomy in the Era of GLAST” The universe is transparent to GeV photons, making this part of the spectrum ideal for obtaining information on high-energy astrophysical phenomena at cosmological distances. The GeV sky was first studied in detail by the Energetic Gamma-Ray Experiment Telescope (EGRET) in the 1990s. Together with an impressive array of data on high-energy systems, the legacy of the EGRET mission includes two persisting puzzles: the nature of 170 yet unidentified gamma-ray sources, and the origin of a diffuse, isotropic, persumably extragalactic gamma-ray background. The launch of the Gamma-ray Large Area Space Telescope in the fall of 2007 will once again open the GeV-window of energies to observations. I will discuss recent progress, using model-independent approaches, on the interconnected questions of unidentified sources and the gamma-ray background, together with additional tests that GLAST will enable us to perform to constrain relevant theories. |