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

Using data from the Wide-field Infrared Survey Explorer (WISE) all-sky survey, we discovered that the nonthermal infrared (IR) emission of blazars, the largest known population of extragalactic γ-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 γ-ray spectral index of Fermi blazars. We name this correlation the infrared–γ-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 10decades in energy. Based on this evidence, we argue that the infrared–γ-ray connection is stronger than the well-known radio–γ-ray connection.