Signatures of multiple episodes of AGN activity in the core of Abell 1795

TL;DR

This study combines radio and X-ray observations to identify multiple signatures of recurrent AGN activity in Abell 1795, revealing a complex feedback history with multiple cavities and aged plasma in the cluster core.

Contribution

First combined radio and X-ray analysis confirming multiple AGN activity episodes and characterizing their signatures in Abell 1795.

Findings

Identification of multiple X-ray cavities associated with AGN activity.

Detection of aged plasma in radio extensions of cavities.

Evidence supporting recurrent AGN feedback shaping cluster core morphology.

Abstract

In this paper we analyze AGN activity signatures in the rich nearby galaxy cluster Abell 1795 aiming to confirm and characterize the long-term feedback history in the system. We combine radio observations at 610 and 235 MHz from the Giant Metrewave Radio Telescope (GMRT) with 3.4 Msec X-ray data from the Chandra Observatory. Extracting radial temperature profiles, as well as X-ray and radio surface brightness profiles in three directions showing major morphological disturbances, we highlight the signatures of activity in the system. For the first time we observe radio emission corresponding to the NW X-ray depression, which provides evidence in favor of the classification of the depression as a cavity. We identify two other X-ray cavities situated NW and SW of the AGN. While the central radio emission corresponding to the inner cavities shows flatter spectral index, the radio extensions associated with the furthest X-ray cavities consist of aged plasma. All observed signatures both in radio and X-ray are consistent with several consecutive episodes of AGN activity, which gave rise to the observed morphology NW and SW from the core. In the southern region, we confirm the cooling wake hypothesis for the origin of the long tail. The deep X-ray data also allows us to distinguish significant distortions in the tail's inner parts, which we attribute to the activity of the AGN.