DA 362: A Gamma-ray Emitting Compact Symmetric Object

TL;DR

This paper reports the discovery of Gamma-ray emission from DA 362, a rare gamma-ray emitting compact symmetric object, providing insights into high-energy processes in this unique class of radio-loud AGN.

Contribution

It presents the first detailed multiwavelength analysis confirming DA 362 as a Gamma-ray emitting CSO, highlighting its unique flaring activity and subluminal jet motion.

Findings

Detected Gamma-ray flaring activity from DA 362.

Confirmed its CSO nature with subluminal jet velocity.

Observed a hard X-ray spectrum suggesting obscuration.

Abstract

The Gamma-ray detection from an astrophysical object indicates the presence of an extreme environment where high-energy radiation is produced. With the continuous monitoring of the Gamma-ray sky by the Fermi Large Area Telescope (LAT), leading to deeper sensitivity, the high-energy Gamma-ray emission has now been detected from a diverse class of jetted active galactic nuclei (AGN). Here, we present the results of a multiwavelength study of the radio source DA~362, which was reported to be a blazar candidate of uncertain type. However, it was recently identified as a bona fide compact symmetric object (CSO) based on its sub-kpc, bi-polar radio morphology, and lack of radio variability. This makes DA~362 the only fourth Gamma-ray emitting object of this enigmatic class of radio-loud AGN. Using five very long baseline interferometry observations covering 1996-2018, we found the jet separation velocity to be subluminal ($v_{\rm app}\sim 0.2c$), thus supporting its CSO nature. Its Fermi-LAT observations revealed a Gamma-ray flaring activity, a phenomenon never detected from the other three Gamma-ray detected CSOs. This object is bright in the near-infrared band but extremely faint in the optical-ultraviolet filters, hinting at possible obscuration. The Swift X-Ray Telescope observation of DA 362 reveals an extremely hard X-ray spectrum, though a strong claim cannot be made due to large uncertainties. We conclude that deeper observations are needed to probe the broadband properties of this enigmatic object and to understand the origin of high-energy Gamma-ray emission.