A BCG with offset cooling: is the AGN feedback cycle broken in A2495?

TL;DR

This study combines radio and X-ray data to analyze the galaxy cluster Abell 2495, revealing offset cooling, potential sloshing effects, and AGN feedback that sustains the cycle despite the cooling offset from the BCG.

Contribution

It provides new insights into the offset cooling process, sloshing effects, and AGN feedback mechanisms in Abell 2495 through multi-wavelength analysis.

Findings

Offset of 6 kpc between BCG and X-ray peak suggests non-central cooling.

Detection of cavities with ages indicating recent AGN activity.

AGN feedback energy is sufficient to sustain the feedback cycle despite cooling offset.

Abstract

We present a combined radio/X-ray analysis of the poorly studied galaxy cluster Abell 2495 (z=0.07923) based on new EVLA and Chandra data. We also analyze and discuss Halpha emission and optical continuum data retrieved from the literature. We find an offset of 6 kpc between the cluster BCG (MCG+02-58-021) and the peak of the X-ray emission, suggesting that the cooling process is not taking place on the central galaxy nucleus. We propose that sloshing of the ICM could be responsible for this separation. Furthermore, we detect a second, 4 kpc offset between the peak of the Halpha emission and that of the X-ray emission. Optical images highlight the presence of a dust filament extending up to 6 kpc in the cluster BCG, and allow us to estimate a dust mass within the central 7 kpc of 1.7e+5 Msun. Exploiting the dust to gas ratio and the L_Halpha-M_mol relation, we argue that a significant amount (up to 10^9 Msun) of molecular gas should be present in the BCG of this cluster. We also investigate the presence of ICM depressions, finding two putative systems of cavities; the inner pair is characterized by t age = 18 Myr and P cav = 1.2e+43 erg/s, the outer one by t age = 53 Myr and P cav = 5.6e+42 erg/s. Their age difference appears to be consistent with the free-fall time of the central cooling gas and with the offset timescale estimated with the Halpha kinematic data, suggesting that sloshing is likely playing a key role in this environment. Furthermore, the cavities' power analysis shows that the AGN energy injection is able to sustain the feedback cycle, despite cooling being offset from the BCG nucleus.