# Fermi Large Area Telescope Measurements of the Diffuse Gamma-Ray Emission at Intermediate Galactic Latitudes

Abstract : The diffuse Galactic gamma-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 gamma-ray emission > 1 GeV relative to diffuse Galactic gamma-ray emission models consistent with directly measured CR spectra (the so-called EGRET GeV excess''). The excess emission was observed in all directions on the sky, and a variety of explanations have been proposed, including beyond-the-Standard-Model scenarios like annihilating or decaying dark matter. The Large Area Telescope (LAT) instrument on the Fermi Gamma-ray Space Telescope has measured the diffuse gamma-ray emission with improved sensitivity and resolution compared to EGRET. We report on LAT measurements of the diffuse gamma-ray emission for energies 100 MeV to 10 GeV and Galactic latitudes 10 deg. <= |b| <= 20 deg. The LAT spectrum for this region of the sky is well reproduced by a diffuse Galactic gamma-ray emission model that is consistent with local CR spectra and inconsistent with the EGRET GeV excess.
Document type :
Journal articles
Domain :

http://hal.in2p3.fr/in2p3-00446920
Contributor : Virginie Mas <>
Submitted on : Wednesday, January 13, 2010 - 4:46:18 PM
Last modification on : Friday, November 27, 2020 - 5:52:10 AM

### Citation

A. A. Abdo, Markus Ackermann, Marco Ajello, B. Anderson, W. B. Atwood, et al.. Fermi Large Area Telescope Measurements of the Diffuse Gamma-Ray Emission at Intermediate Galactic Latitudes. Physical Review Letters, American Physical Society, 2009, 103, pp.251101. ⟨10.1103/PhysRevLett.103.251101⟩. ⟨in2p3-00446920⟩

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