Identification of the infrared non-thermal emission in Blazars

TL;DR

This paper demonstrates how WISE infrared data can effectively distinguish blazars from other sources using a specific color-color diagram, aiding in identifying blazar candidates and counterparts of gamma-ray sources.

Contribution

The study introduces the WISE Blazar Strip (WBS), a new infrared diagnostic tool for identifying blazars and their counterparts in gamma-ray observations.

Findings

The WISE Blazar Strip effectively separates thermal and non-thermal sources.

The WBS can identify new blazar candidates and uncertain types.

Application to VER J 0648+152 confirmed the utility of the WBS.

Abstract

Blazars constitute the most interesting and enigmatic class of extragalactic gamma-ray sources dominated by non-thermal emission. In this Letter, we show how the WISE infrared data make possible to identify a distinct region of the [3.4]-[4.6]-[12] micron color-color diagram where the sources dominated by the the thermal radiation are separated from those dominated by non-thermal emission, in particular the blazar population. This infrared non-thermal region delineated as the WISE Blazar Strip (WBS), it is a powerful new diagnostic tool when the full WISE survey data is released. The WBS can be used to extract new blazar candidates, to identify those of uncertain type and also to search for the counterparts of unidentified gamma-ray sources. We show one example of the value of the use of the WBS identifying the TeV source VER J 0648+152, recently discovered by VERITAS.