The Star-Forming Galaxy Contribution to the Cosmic MeV and GeV Gamma-Ray Background

Abstract

While star-forming galaxies could be major contributors to the cosmic GeV $\gamma$-ray background, they are expected to be MeV-dim because of the "pion bump" falling off below ~100 MeV. However, there are very few observations of galaxies in the MeV range, and other emission processes could be present. We investigate the MeV background from star-forming galaxies by running one-zone models of cosmic ray populations, including Inverse Compton and bremsstrahlung, as well as nuclear lines (including ${}^{26}$Al), emission from core-collapse supernovae, and positron annihilation emission, in addition to the pionic emission. We use the Milky Way and M82 as templates of normal and starburst galaxies, and compare our models to radio and GeV--TeV $\gamma$-ray data. We find that (1) higher gas densities in high-z normal galaxies lead to a strong pion bump, (2) starbursts may have significant MeV emission if their magnetic field strengths are low, and (3) cascades can contribute to the MeV emission of starbursts if they emit mainly hadronic $\gamma$-rays. Our fiducial model predicts that most of the unresolved GeV background is from star-forming galaxies, but this prediction is uncertain by an order of magnitude. About ~2% of the claimed 1 MeV background is diffuse emission from star-forming galaxies; we place a firm upper limit of <~10% based on the spectral shape of the background. The star-formation contribution is constrained to be small, because its spectrum is peaked, while the observed background is steeply falling with energy through the MeV-GeV range.

Published in ApJ, 27 pages, emulateapj format. Readers may be interested in the concurrent paper by Chakraborty and Fields (arXiv:1206.0770), a calculation of the Inverse Compton background from star-forming galaxies

References in corpus (45)

• The synthesis of the cosmic X-ray background in the Chandra and XMM-Newton era
• The Spectrum of the Isotropic Diffuse Gamma-Ray Emission Derived From First-Year Fermi Large Area Telescope Data
• The nucleosynthesis of Al26 and Fe60 in solar metallicity stars extending in mass from 11 to 120 Msun: the hydrostatic and explosive contributions
• GeV Observations of Star-forming Galaxies with \textit{Fermi} LAT
• Parameterization of Gamma, e^+/- and Neutrino Spectra Produced by p-p Interaction in Astronomical Environment
• SHARC-2 350 Micron Observations of Distant Submillimeter Selected Galaxies
• The present-day star formation rate of the Milky-Way determined from Spitzer detected young stellar objects
• A connection between star formation activity and cosmic rays in the starburst galaxy M 82
• Global cosmic-ray related luminosity and energy budget of the Milky Way
• Inverse Compton Origin of the Hard X-Ray and Soft Gamma-Ray Emission from the Galactic Ridge
• Discrete sources as the origin of the Galactic X-ray ridge emission
• A unified empirical model for infrared galaxy counts based on observed physical evolution of distant galaxies
• Magnetic Fields in Starburst Galaxies and The Origin of the FIR-Radio Correlation
• Cosmic X-ray background and Earth albedo Spectra with Swift/BAT
• Detection of Gamma Rays From a Starburst Galaxy
• The Fermi-LAT high-latitude Survey: Source Count Distributions and the Origin of the Extragalactic Diffuse Background
• Iron line and diffuse hard X-ray emission from the starburst galaxy M82
• The Starburst Contribution to the Extra-Galactic Gamma-Ray Background
• Wild at Heart:-The Particle Astrophysics of the Galactic Centre
• INTEGRAL SPI All-Sky View in Soft Gamma Rays: Study of Point Source and Galactic Diffuse Emissions
• Fermi Large Area Telescope observations of Local Group galaxies: Detection of M31 and search for M33
• Gamma-Rays from Decaying Dark Matter
• Cosmic Gamma-Ray Background from Star-Forming Galaxies
• Winds, Clumps, and Interacting Cosmic Rays in M82
• Relaxation of Blazar Induced Pair Beams in Cosmic Voids
• M82 - A radio continuum and polarisation study I. Data reduction and cosmic ray propagation
• Spectral analysis and interpretation of the γ-ray emission from the Starburst galaxy NGC 253
• Statistics of Cosmological Black Hole Jet Sources: Blazar Predictions for GLAST
• Gamma-Ray and Neutrino Backgrounds as Probes of the High-Energy Universe: Hints of Cascades, General Constraints, and Implications for TeV Searches
• Circum-Galactic Gas and the Isotropic Gamma Ray Background
• Active Galactic Nuclei, Neutrinos, and Interacting Cosmic Rays in NGC 253 & NGC 1068
• The Cosmic MeV Gamma-ray Background and Hard X-ray Spectra of Active Galactic Nuclei: Implications for the Origin of Hot AGN Coronae
• Contribution from Star-Forming Galaxies to the Cosmic Gamma-Ray Background Radiation
• Discovery of GeV Emission from the Circinus galaxy with the Fermi-LAT
• Revealing Type Ia supernova physics with cosmic rates and nuclear gamma rays
• Properties of Nearby Starburst Galaxies Based on their Diffuse Gamma-ray Emission
• Angular power spectrum of gamma-ray sources for GLAST: blazars and clusters of galaxies
• Diffuse Gamma Rays from the Galactic Plane: Probing the "GeV Excess" and Identifying the "TeV Excess"
• The FIR-Radio Relationship at High and Low Redshift
• Radio source stacking and the infrared / radio correlation at microJy flux densities
• A Comprehensive Search for Gamma-Ray Lines in the First Year of Data from the INTEGRAL Spectrometer
• Inverse Compton Contribution to the Star-Forming Extragalactic Gamma-Ray Background
• Design and Performance of the Soft Gamma-ray Detector for the NeXT mission
• A SCUBA/Spitzer Investigation of the Far Infra-Red Extragalactic Background
• Assessing The Starburst Contribution to the Gamma-Ray and Neutrino Backgrounds

Cited by in corpus (40)

• The spectrum of isotropic diffuse gamma-ray emission between 100 MeV and 820 GeV
• Science with e-ASTROGAM (A space mission for MeV-GeV gamma-ray astrophysics)
• Constraining High-Energy Cosmic Neutrino Sources: Implications and Prospects
• The Origin of the Extragalactic Gamma-Ray Background and Implications for Dark-Matter Annihilation
• Star-forming galaxies as the origin of diffuse high-energy backgrounds: Gamma-ray and neutrino connections, and implications for starburst history
• The nature of the Diffuse Gamma-Ray Background
• A simplified view of blazars: the neutrino background
• Astrophysical Sources of High Energy Neutrinos in the IceCube Era
• What IceCube data tell us about neutrino emission from star-forming galaxies (so far)
• A novel approach in the WIMP quest: Cross-Correlation of Gamma-Ray Anisotropies and Cosmic Shear
• Deciphering Contributions to the Extragalactic Gamma-Ray Background from 2 GeV to 2 TeV
• Spatially Resolving a Starburst Galaxy at Hard X-ray Energies: NuSTAR, Chandra, AND VLBA Observations of NGC 253
• The TeV Diffuse Cosmic Neutrino Spectrum and the Nature of Astrophysical Neutrino Sources
• Unveiling the Gamma-ray Source Count Distribution Below the Fermi Detection Limit with Photon Statistics
• Equipartition and Cosmic Ray Energy Densities in Central Molecular Zones of Starbursts
• Are Starburst Galaxies Proton Calorimeters?
• Tomographic-spectral approach for dark matter detection in the cross-correlation between cosmic shear and diffuse gamma-ray emission
• Star-Forming Galaxies Significantly Contribute to the Isotropic Gamma-Ray Background
• Constraining Gamma-Ray Emission from Luminous Infrared Galaxies with Fermi-LAT; Tentative Detection of Arp 220
• Constraints on Dark Matter Annihilation/Decay from the Isotropic Gamma-Ray Background
• High-energy gamma-ray and neutrino production in star-forming galaxies across cosmic time: Difficulties in explaining the IceCube data
• Background modelling for $\gamma$-ray spectroscopy with INTEGRAL/SPI
• Revisiting the Contributions of Supernova and Hypernova Remnants to the Diffuse High-Energy Backgrounds: Constraints on Very-High-Redshift Injections
• Fermi-LAT gamma-ray anisotropy and intensity explained by unresolved Radio-Loud Active Galactic Nuclei
• Extragalactic gamma-ray background from AGN winds and star-forming galaxies in cosmological galaxy formation models
• The origin of the cosmic gamma-ray background in the MeV range
• Probing the Extragalactic Cosmic Rays origin with gamma-ray and neutrino backgrounds
• On ultra high energy cosmic rays and their resultant gamma rays
• Source-count Distribution of Gamma-Ray Blazars
• IceCube Neutrinos from Hadronically Powered Gamma-Ray Galaxies
• Revisiting the constraints on primordial black hole abundance with the isotropic gamma ray background
• Characterising the signatures of star-forming galaxies in the extra-galactic $\gamma$-ray background
• Measurement of redshift dependent cross correlation of HSC clusters and Fermi $\gamma$ rays
• Lower Bound on the Cosmic TeV Gamma-ray Background Radiation
• Gamma-rays from kilonovae and the cosmic gamma-ray background
• Secondary Radio and X-ray Emissions from Galaxy Mergers
• MeV cosmic-ray electrons modify the TeV pair-beam plasma instability
• Cosmic Radioactivity and Galactic Chemical Evolution
• Extragalactic Searches for Dark Matter Annihilation
• Diffuse continuum emission and large extended sources at MeV energies