Diffuse $\gamma$-ray emission from misaligned active galactic nuclei

TL;DR

This paper models the diffuse gamma-ray emission from misaligned active galactic nuclei (MAGN), establishing a correlation with radio luminosity, constraining the gamma-ray luminosity function, and estimating the MAGN contribution to the isotropic gamma-ray background.

Contribution

It introduces a new correlation between gamma-ray and radio-core luminosities for MAGN, constrains the gamma-ray luminosity function, and estimates their contribution to the gamma-ray background.

Findings

MAGN can contribute up to nearly the entire IGRB.

The gamma-ray luminosity correlates with radio-core luminosity.

Estimated MAGN flux ranges from 10% to nearly 100% of the IGRB.

Abstract

We calculate the diffuse $\gamma$-ray emission due to the population of misaligned AGN (MAGN) unresolved by the Large Area Telescope (LAT) on the {\it Fermi} Gamma-ray Space Telescope ({\it Fermi}). A correlation between the $\gamma$-ray luminosity and the radio-core luminosity is established and demonstrated to be physical by statistical tests, as well as compatible with upper limits based on {\it Fermi}-LAT data for a large sample of radio-loud MAGN. We constrain the derived $\gamma$-ray luminosity function by means of the source count distribution of the MAGN detected by the {\it Fermi}-LAT. We finally estimate the diffuse $\gamma$-ray flux due to the whole MAGN population which ranges from 10% up to nearly the entire measured Isotropic Gamma-Ray Background (IGRB). We evaluate also the room left to galactic DM at high latitudes ($>10^\circ$), by taking into account the results on the MAGN together with the other significant galactic and extragalactic $\gamma$-rays emitting sources.