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Title: COMPONENTS OF THE EXTRAGALACTIC GAMMA-RAY BACKGROUND

Abstract

We present new theoretical estimates of the relative contributions of unresolved blazars and star-forming galaxies to the extragalactic {gamma}-ray background (EGB) and discuss constraints on the contributions from alternative mechanisms such as dark matter annihilation and truly diffuse {gamma}-ray production. We find that the Fermi source count data do not rule out a scenario in which the EGB is dominated by emission from unresolved blazars, though unresolved star-forming galaxies may also contribute significantly to the background, within order-of-magnitude uncertainties. In addition, we find that the spectrum of the unresolved star-forming galaxy contribution cannot explain the EGB spectrum found by EGRET at energies between 50 and 200 MeV, whereas the spectrum of unresolved flat spectrum radio quasars, when accounting for the energy-dependent effects of source confusion, could be consistent with the combined spectrum of the low-energy EGRET EGB measurements and the Fermi-Large Area Telescope EGB measurements.

Authors:
 [1];  [2]
  1. Astrophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
  2. Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
Publication Date:
OSTI Identifier:
21578321
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 736; Journal Issue: 1; Other Information: DOI: 10.1088/0004-637X/736/1/40; Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BACKGROUND RADIATION; COSMIC PHOTONS; GALAXIES; BOSONS; COSMIC RADIATION; ELEMENTARY PARTICLES; IONIZING RADIATIONS; MASSLESS PARTICLES; PHOTONS; RADIATIONS

Citation Formats

Stecker, Floyd W., and Venters, Tonia M., E-mail: floyd.w.stecker@nasa.gov. COMPONENTS OF THE EXTRAGALACTIC GAMMA-RAY BACKGROUND. United States: N. p., 2011. Web. doi:10.1088/0004-637X/736/1/40.
Stecker, Floyd W., & Venters, Tonia M., E-mail: floyd.w.stecker@nasa.gov. COMPONENTS OF THE EXTRAGALACTIC GAMMA-RAY BACKGROUND. United States. doi:10.1088/0004-637X/736/1/40.
Stecker, Floyd W., and Venters, Tonia M., E-mail: floyd.w.stecker@nasa.gov. Wed . "COMPONENTS OF THE EXTRAGALACTIC GAMMA-RAY BACKGROUND". United States. doi:10.1088/0004-637X/736/1/40.
@article{osti_21578321,
title = {COMPONENTS OF THE EXTRAGALACTIC GAMMA-RAY BACKGROUND},
author = {Stecker, Floyd W. and Venters, Tonia M., E-mail: floyd.w.stecker@nasa.gov},
abstractNote = {We present new theoretical estimates of the relative contributions of unresolved blazars and star-forming galaxies to the extragalactic {gamma}-ray background (EGB) and discuss constraints on the contributions from alternative mechanisms such as dark matter annihilation and truly diffuse {gamma}-ray production. We find that the Fermi source count data do not rule out a scenario in which the EGB is dominated by emission from unresolved blazars, though unresolved star-forming galaxies may also contribute significantly to the background, within order-of-magnitude uncertainties. In addition, we find that the spectrum of the unresolved star-forming galaxy contribution cannot explain the EGB spectrum found by EGRET at energies between 50 and 200 MeV, whereas the spectrum of unresolved flat spectrum radio quasars, when accounting for the energy-dependent effects of source confusion, could be consistent with the combined spectrum of the low-energy EGRET EGB measurements and the Fermi-Large Area Telescope EGB measurements.},
doi = {10.1088/0004-637X/736/1/40},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 736,
place = {United States},
year = {2011},
month = {7}
}