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The 2009 Fermi Symposium

Fermi LAT Observations of Diffuse Gamma-Ray Emission in the Galactic Center

Seth Digel, KIPAC/SLAC


The Milky Way is a bright, diffuse source of high-energy gamma rays from interactions of cosmic rays with interstellar gas and photons and contains many discrete sources of gamma rays - e.g., pulsars, pulsar wind nebulae, supernova remnants, X-ray binaries - that are related to Population I objects. These in turn are associated with dense interstellar gas and either directly or indirectly are the sources of much of the infrared-UV interstellar radiation field. The Galactic center region is the brightest in diffuse gamma-ray emission, and has a uniquely high density of potential gamma-ray emitters. The Fermi Large Area Telescope has surveyed the high-energy gamma-ray sky with unprecedented sensitivity. The Galactic center region is particularly challenging to study, owing to the density of sources and the difficulty of measuring the distribution of interstellar gas, as well as the long lines of sight to and through the Galactic center in the Milky Way. In this presentation we describe the efforts of the LAT team to model the diffuse emission in this region, for study in its own right and in support of detecting and characterizing the discrete sources of high-energy gamma rays.