Institute: MPI für Physik     Collection: YB 2016     Display Documents

ID: 716499.0, MPI für Physik / YB 2016
The spectrum of isotropic diffuse gamma-ray emission between 100 MeV and 820 GeV
Authors:
Date of Publication (YYYY-MM-DD):2015
Title of Journal:Astrophysical Journal
Journal Abbrev.:Astrophys.J.
Issue / Number:799
Start Page:86
Audience:Not Specified
Intended Educational Use:No
Abstract / Description:The {\\gamma}-ray sky can be decomposed into individually detected sources, diffuse emission attributed to the interactions of Galactic cosmic rays with gas and radiation fields, and a residual all-sky emission component commonly called the isotropic diffuse {\\gamma}-ray background (IGRB). The IGRB comprises all extragalactic emissions too faint or too diffuse to be resolved in a given survey, as well as any residual Galactic foregrounds that are approximately isotropic. The first IGRB measurement with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope (Fermi) used 10 months of sky-survey data and considered an energy range between 200 MeV and 100 GeV. Improvements in event selection and characterization of cosmic-ray backgrounds, better understanding of the diffuse Galactic emission, and a longer data accumulation of 50 months, allow for a refinement and extension of the IGRB measurement with the LAT, now covering the energy range from 100 MeV to 820 GeV. The IGRB spectrum shows a significant high-energy cutoff feature, and can be well described over nearly four decades in energy by a power law with exponential cutoff having a spectral index of $2.32\\pm0.02$ and a break energy of $(279\\pm52)$ GeV using our baseline diffuse Galactic emission model. The total intensity attributed to the IGRB is $(7.2\\pm0.6) \\times 10^{-6}$ cm$^{-2}$ s$^{-1}$ sr$^{-1}$ above 100 MeV, with an additional $+15$%/$-30$% systematic uncertainty due to the Galactic diffuse foregrounds.
Classification / Thesaurus:Fermi
Comment of the Author/Creator:Accepted by The Astrophysical Journal
External Publication Status:published
Document Type:Article
Communicated by:MPI für Physik
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