Abstract
The diffuse galactic -ray emission is produced by cosmic rays (CRs) interacting with the interstellar gas and radiation field. Measurements by the Energetic Gamma-Ray Experiment Telescope (EGRET) instrument on the Compton Gamma-Ray Observatory indicated excess -ray emission relative to diffuse galactic -ray emission models consistent with directly measured CR spectra (the so-called “EGRET GeV excess”). The Large Area Telescope (LAT) instrument on the Fermi Gamma-Ray Space Telescope has measured the diffuse -ray emission with improved sensitivity and resolution compared to EGRET. We report on LAT measurements for energies 100 MeV to 10 GeV and galactic latitudes . The LAT spectrum for this region of the sky is well reproduced by a diffuse galactic -ray emission model that is consistent with local CR spectra and inconsistent with the EGRET GeV excess.
- Received 13 May 2009
DOI:https://doi.org/10.1103/PhysRevLett.103.251101
©2009 American Physical Society
Synopsis
Do cosmic rays account for all the gamma rays in diffuse galactic radiation?
Published 21 December 2009
New data are inconsistent with previous measurements that showed an unexpected excess of diffuse gamma-ray emission in the Galaxy.
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