The nature of the variable millimetre-selected AGN in the Brightest Cluster Galaxy of Abell 851

TL;DR

This paper reports the detection of a variable, low luminosity AGN in the Brightest Cluster Galaxy of Abell 851 through millimeter observations, suggesting ongoing radio mode feedback in a massive cluster.

Contribution

First detection of a variable millimeter continuum source in the BCG of Abell 851, linking it to low luminosity AGN activity and feedback mechanisms.

Findings

Detection of a bright 3mm continuum source in the BCG.

Evidence of a flat, variable core source consistent with low luminosity AGN.

Comparison with multi-frequency data supports AGN classification.

Abstract

We present the detection of a bright 3mm continuum source in the Brightest Cluster Galaxy (BCG) in Abell 851 (z=0.411) with the NOrthern Extended Millimeter Array (NOEMA). When this detection is compared to other multi-frequency observations across 21cm-100um, including new Arcminute Microkelvin Imager 15GHz observations, we find evidence for a relatively flat, variable core source associated with the BCG. The radio power and amplitude of variability observed in this galaxy is consistent with the cores in lower redshift BCGs in X-ray-selected clusters, and the flat mm-cm spectrum is suggestive of the BCG being a low luminosity AGN archetype. The discovery of this system could provide a basis for a long-term study of the role of low luminosity radio mode 'regulatory' feedback in massive clusters.