A BCG with Offset Cooling: Is the AGN Feedback Cycle Broken in A2495?

Journal
Date Issued
2019
Author(s)
Pasini, T.
•
•
Brighenti, F.
•
Temi, P.
•
Amblard, A.
•
Hamer, S. L.
•
•
O’Sullivan, E.
•
DOI
Abstract
We present a combined radio/X-ray analysis of the poorly studied galaxy cluster A2495 (z = 0.07923) based on new EVLA and Chandra data. We also analyze and discuss Hα emission and optical continuum data retrieved from the literature. We find an offset of ∼6 kpc between the cluster brightest cluster galaxy (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 intracluster medium (ICM) could be responsible for this separation. Furthermore, we detect a second, ∼4 kpc offset between the peak of the Hα 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 1.7 × 105 M ⊙. Exploiting the dust-to-gas ratio and the L Hα -M mol relation, we argue that a significant amount (up to 109 M ⊙) 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 ∼ 1.2 × 1043 erg s-1, the outer one by t age ∼ 53 Myr and P cav ∼ 5.6 × 1042 erg s-1. Their age difference appears to be consistent with the freefall time of the central cooling gas and with the offset timescale estimated with the Hα kinematic data, suggesting that sloshing is likely playing a key role in this environment. Furthermore, the cavities’ power analysis shows that the active galactic nucleus energy injection is able to sustain the feedback cycle, despite cooling being offset from the BCG nucleus.
Volume
885
Issue
2
Start page
111
Uri
Url
Issn Identifier
0004-637X
Ads BibCode
2019ApJ...885..111P
Rights
open.access
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