Blazars are radio-loud Active Galactic Nuclei (AGN) whose jets have a very small angle to our line of sight. Observationally, the radio emission are mostly compact or a compact-core with a 1-sided jet. With 2.5′′ resolution at 3 GHz, the Very Large Array Sky Survey (VLASS) enables us to resolve the structure of some blazar candidates in the sky north of Decl. −40 deg. We introduce an algorithm to classify radio sources as either blazar-like or non-blazar-like based on their morphology in the VLASS images. We apply our algorithm to three existing catalogs, including one of known blazars (Roma-BzCAT) and two of blazar candidates identified by WISE colors and radio emission (WIBRaLS, KDEBLLACS). We show that in all three catalogs, there are objects with morphology inconsistent with being blazars. Considering all the catalogs, more than 12% of the candidates are unlikely to be blazars, based on this analysis. Notably, we show that 3% of the Roma-BzCAT "confirmed" blazars could be a misclassification based on their VLASS morphology. The resulting table with all sources and their radio morphological classification is available online.
@article{arxiv.2401.04009,
title = {Recognizing Blazars Using Radio Morphology from the VLA Sky Survey},
author = {Zhang-Liang Xie and Eduardo Banados and Silvia Belladitta and Chiara Mazzucchelli and Jan-Torge Schindler and Frederick B. Davies and Bram P. Venemans},
journal= {arXiv preprint arXiv:2401.04009},
year = {2024}
}
Comments
21 pages, 11 figures, accepted for publication in The Astrophysical Journal