Quasar-driven outflows account for the missing extragalactic gamma-ray background

Abstract

The origin of the extragalactic $\gamma$-ray background permeating throughout the Universe remains a mystery forty years after its discovery. The extrapolated population of blazars can account for only half of the background radiation at the energy range of ~ 0.1-10 GeV. Here we show that quasar-driven outflows generate relativistic protons that produce the missing component of the extragalactic $\gamma$-ray background and naturally match its spectral fingerprint, with a generic break above ~ 1 GeV. The associated $\gamma$-ray sources are too faint to be detected individually, explaining why they had not been identified so far. However, future radio observations may image their shock fronts directly. Our best fit to the Fermi-LAT observations of extragalactic $\gamma$-ray background spectrum provides constraints on the outflow parameters that agree with observations of these outflows and theoretical predictions.

Published in Nature Physics

References in corpus (40)

• Observational Evidence of AGN Feedback
• An Observational Determination of the Bolometric Quasar Luminosity Function
• Giant Gamma-ray Bubbles from Fermi-LAT: AGN Activity or Bipolar Galactic Wind?
• Observational constraints on growth of massive black holes
• Energy spectra of gamma-rays, electrons and neutrinos produced at proton-proton interactions in the very high energy regime
• Massive Molecular Outflows and Evidence for AGN Feedback from CO Observations
• Detection of the Characteristic Pion-Decay Signature in Supernova Remnants
• The spectrum of isotropic diffuse gamma-ray emission between 100 MeV and 820 GeV
• Linear Regression for Astronomical Data with Measurement Errors and Intrinsic Scatter
• Powerful Outflows and Feedback from Active Galactic Nuclei
• Simulations of Ion Acceleration at Non-relativistic Shocks. I. Acceleration Efficiency
• The physics of galactic winds driven by active galactic nuclei
• The Third Catalog of Active Galactic Nuclei Detected by the Fermi Large Area Telescope
• The First Catalog of Active Galactic Nuclei Detected by the Fermi Large Area Telescope
• GeV Observations of Star-forming Galaxies with \textit{Fermi} LAT
• Wind from the black-hole accretion disk driving a molecular outflow in an active galaxy
• Intergalactic Photon Spectra from the Far IR to the UV Lyman Limit for $0<z<6$ and the Optical Depth of the Universe to High Energy Gamma-Rays
• Clearing Out a Galaxy
• The radio luminosity function from the low-frequency 3CRR, 6CE & 7CRS complete samples
• VLBI Observations of a Complete Sample of Radio Galaxies. 10 Years Later
• Fermi Gamma-ray Imaging of a Radio Galaxy
• The Fermi Bubbles: Giant, Multi-Billion-Year-Old Reservoirs of Galactic Center Cosmic Rays
• The Origin of the Extragalactic Gamma-Ray Background and Implications for Dark-Matter Annihilation
• Fermi Large Area Telescope Observations of Misaligned AGN
• Quasar Outflows and AGN Feedback in the Far UV: HST/COS Observations of QSO HE0238-1904
• Contribution of the Gamma-ray Loud Radio Galaxies Core Emissions to the Cosmic MeV and GeV Gamma-Ray Background Radiation
• The nature of the Diffuse Gamma-Ray Background
• Diffuse $\gamma$-ray emission from misaligned active galactic nuclei
• Evidence for Jet Domination of the Nuclear Radio Emission in Low-luminosity Active Galactic Nuclei
• A Unified Model of the Fermi Bubbles, Microwave Haze, and Polarized Radio Lobes: Reverse Shocks in the Galactic Center's Giant Outflows
• Cosmic-ray acceleration in supernova remnants: non-linear theory revised
• Magnetic Fields in the Center of the Perseus Cluster
• Radio-loud active galaxies in the northern ROSAT All-Sky Survey. I. Radio identifications
• The Australia Telescope 20 GHz (AT20G) Survey: The Bright Source Sample
• Chandra and XMM-Newton Observations of NGC 6251
• Corrected Table for the Parametric Coefficients for the Optical Depth of the Universe to Gamma-rays at Various Redshifts
• Contemporaneous VLBA 5 GHz Observations of LAT-Detected Blazars
• A new sample of large angular size radio galaxies. III. Statistics and evolution of the grown population
• Search for Early Gamma-ray Production in Supernovae Located in a Dense Circumstellar Medium with the Fermi LAT
• Probing the gaseous halo of galaxies through non-thermal emission from AGN-driven outflows

Cited by in corpus (17)

• Cool Outflows in Galaxies and their Implications
• Constraints on gamma-ray and neutrino emission from NGC 1068 with the MAGIC telescopes
• Can winds driven by active galactic nuclei account for the extragalactic gamma-ray and neutrino backgrounds?
• Star-Forming Galaxies Significantly Contribute to the Isotropic Gamma-Ray Background
• Gamma rays from Fast Black-Hole Winds
• Extragalactic gamma-ray background from AGN winds and star-forming galaxies in cosmological galaxy formation models
• Unveiling the origin of the gamma-ray emission in NGC 1068 with the Cherenkov Telescope Array
• Cumulative neutrino background from quasar-driven outflows
• Characterising the signatures of star-forming galaxies in the extra-galactic $\gamma$-ray background
• Ultra high energy cosmic rays from non-relativistic quasar outflows
• Extragalactic Observatory Science with the ASTRI Mini-Array at the Observatorio del Teide
• Ultra-high-energy cosmic rays from ultra-fast outflows of active galactic nuclei
• Gamma-ray Emission from Galaxies Hosting Molecular Outflows
• The extragalactic $\gamma$-ray background: imprints from the physical properties and evolution of star-forming galaxy populations
• Secondary Radio and X-ray Emissions from Galaxy Mergers
• The Disk Wind Contribution to the Gamma-Ray emission from the nearby Seyfert Galaxy GRS 1734-292
• Revisiting Disk Winds in Active Galactic Nuclei as an Origin of Cosmic Gamma-ray and Neutrino Backgrounds