The Spectrum of the Isotropic Diffuse Gamma-Ray Emission Derived From First-Year Fermi Large Area Telescope Data

Abstract

We report on the first Fermi Large Area Telescope (LAT) measurements of the so-called "extra-galactic" diffuse gamma-ray emission (EGB). This component of the diffuse gamma-ray emission is generally considered to have an isotropic or nearly isotropic distribution on the sky with diverse contributions discussed in the literature. The derivation of the EGB is based on detailed modelling of the bright foreground diffuse Galactic gamma-ray emission (DGE), the detected LAT sources and the solar gamma-ray emission. We find the spectrum of the EGB is consistent with a power law with differential spectral index g = 2.41+/-0.05 and intensity, I(> 100 MeV) = (1.03+/-0.17) 10^-5 cm^-2 s^-1 sr^-1, where the error is systematics dominated. Our EGB spectrum is featureless, less intense, and softer than that derived from EGRET data.

4 figures, 1 table, supplementary material, accepted by Physical Review Letters

References in corpus (6)

• Measurement of the Cosmic Ray e+ plus e- spectrum from 20 GeV to 1 TeV with the Fermi Large Area Telescope
• Parameterization of Gamma, e^+/- and Neutrino Spectra Produced by p-p Interaction in Astronomical Environment
• Inverse Compton Origin of the Hard X-Ray and Soft Gamma-Ray Emission from the Galactic Ridge
• Fermi LAT Observations of the Vela Pulsar
• Gamma-ray emission from the solar halo and disk: a study with EGRET data
• The Extragalactic Gamma Ray Background

Cited by in corpus (35)

• Giant Gamma-ray Bubbles from Fermi-LAT: AGN Activity or Bipolar Galactic Wind?
• Global cosmic-ray related luminosity and energy budget of the Milky Way
• Observations of the young supernova remnant RX J1713.7-3946 with the Fermi Large Area Telescope
• GZK Neutrinos after the Fermi-LAT Diffuse Photon Flux Measurement
• The Fermi-LAT high-latitude Survey: Source Count Distributions and the Origin of the Extragalactic Diffuse Background
• Constraints on the induced gravitational wave background from primordial black holes
• A new viable region of the inert doublet model
• Fermi-LAT Observations of Two Gamma-Ray Emission Components from the Quiescent Sun
• Cosmic Gamma-Ray Background from Star-Forming Galaxies
• Contribution from Star-Forming Galaxies to the Cosmic Gamma-Ray Background Radiation
• T(13) Flavor Symmetry and Decaying Dark Matter
• Universally Leptophilic Dark Matter From Non-Abelian Discrete Symmetry
• Fermi Gamma-ray Space Telescope: High-Energy Results from the First Year
• The cosmic X-ray and gamma-ray background from dark matter annihilation
• Gamma-ray Constraints on Effective Interactions of the Dark Matter
• Light Higgs Boson, Light Dark Matter and Gamma Rays
• Indirect detection of gravitino dark matter including its three-body decays
• Broken R-Parity in the Sky and at the LHC
• Charge Asymmetric Cosmic Ray Signals From Dark Matter Decay
• No Indications of Axion-Like Particles From Fermi
• The High Energy Budget Allocations in Shocks and GRB
• Constraining the Emissivity of Ultrahigh Energy Cosmic Rays in the Distant Universe with the Diffuse Gamma-ray Emission
• "Discrepant hardenings" in cosmic ray spectra: a first estimate of the effects on secondary antiproton and diffuse gamma-ray yields
• Systematic effects in the extraction of the 'WMAP haze'
• The impact of propagation uncertainties on the potential Dark Matter contribution to the Fermi LAT mid-latitude gamma-ray data
• Black Holes in our Galactic Halo: Compatibility with FGST and PAMELA Data and Constraints on the First Stars
• Primordial Black Hole as a Source of the Boost Factor
• Testing Lorentz Invariance with Neutrinos from Ultrahigh Energy Cosmic Ray Interactions
• A Robust Approach to Constraining Dark Matter from Gamma-Ray Data
• Decaying Dark Matter in Supersymmetric Model and Cosmic-Ray Observations
• Exploring SUSY light Higgs boson scenarios via dark matter experiments
• Constraint on dark matter annihilation with dark star formation using Fermi extragalactic diffuse gamma-ray background data
• Constraints on a Non-thermal History from Galactic Dark Matter Spikes
• Neutralino dark matter with a Light Higgs
• Reconstructing Dark Matter Properties via Gamma-Rays with Fermi-LAT