The Discovery of a Remnant Radio Galaxy in A2065 Using GMRT

TL;DR

This paper reports the discovery of a remnant radio galaxy in cluster A2065 using GMRT and Chandra data, revealing its structure, possible shock interaction, and connection to the host AGN, contributing to understanding remnant radio sources.

Contribution

First detection of a remnant radio galaxy in A2065 with detailed multiwavelength analysis highlighting shock interaction and AGN connection.

Findings

Elongated, bar-shaped remnant radio structure of ~72x152 kpc.

Surface-brightness edge in X-ray gas indicating possible shock.

Spectral flattening suggesting re-energization of old plasma.

Abstract

The upgraded Giant Metrewave Radio Telescope (GMRT) has been used to map the cluster A2065 at z = 0.0726. We report the discovery of a remnant radio galaxy at the peripheral cluster region. The spatially resolved radio emission from the remnant radio galaxy shows an elongated, bar-shaped structure, whose size is $\approx$ 52$^{\prime\prime}$ $\times$ 110$^{\prime\prime}$ ($\simeq$ 72 $\times$ 152 kpc$^2$). Our study with the multiwavelength GMRT data and \textit{Chandra} data shows that across the remnant radio galaxy there is a hint of a surface-brightness edge in the hot X-ray gas. We detect tentative flattening of the radio spectral index as the old plasma at the near end of the surface-brightness edge is reinvigorated by the passage of possible shock front and shows the expected change in radio emission characteristics. We suggest that the remnant radio galaxy has been seeded by the lobes of the active galactic nucleus (AGN), hosted by the WISEA J152228.01$+$274141.3 source, demonstrating the connection between AGNs and remnant radio sources. Although the number of known remnant radio sources is beginning to increase, we emphasize the need for better data to understand the physics and nature of poorly understood remnant radio sources.