The nature of the variable millimetre–selected AGN in the brightest cluster galaxy of Abell 851

Abstract

ABSTRACT We present the detection of a bright 3 mm continuum source in the brightest cluster galaxy (BCG) in Abell 0851 (z = 0.411) with the NOrthern Extended Millimeter Array (NOEMA). When this detection is compared to other multifrequency observations across 21cm–$100 {\mu {m}}$, including new Arcminute Microkelvin Imager 15 GHz 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 active galactic nucleus 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.