The Infrared-Gamma-Ray Connection: A WISE View of the Extragalactic Gamma-Ray Sky

TL;DR

This study reveals a strong correlation between infrared and gamma-ray emissions in blazars, providing insights into particle acceleration and jet physics in extragalactic sources, based on WISE and Fermi data analysis.

Contribution

We confirm and strengthen the infrared--gamma-ray connection in blazars using the latest WISE and Fermi data, highlighting its significance over the radio--gamma-ray link.

Findings

A tight correlation between mid-IR colors and gamma-ray spectral index.

The infrared--gamma-ray connection links emission powers and particle spectra.

The connection is stronger than the radio--gamma-ray correlation.

Abstract

Using data from the WISE all-sky survey we discovered that the non-thermal infrared (IR) emission of blazars, the largest known population of extragalactic gamma-ray sources, has peculiar spectral properties. In this work, we confirm and strengthen our previous analyses using the latest available releases of both the WISE and the Fermi source catalogs. We also show that there is a tight correlation between the mid-IR colors and the gamma-ray spectral index of Fermi blazars. We name this correlation "the infrared--gamma-ray connection". We discuss how this connection links both the emitted powers and the spectral shapes of particles accelerated in jets arising from blazars over ten decades in energy. Based on this evidence, we argue that the infrared--gamma-ray connection is stronger than the well known radio--gamma-ray connection.