AGN jets and a fanciful trio of black holes in the Abell 85 Brightest Cluster Galaxy

Juan P. Madrid

Published 2020-12-19Version 1

A new radio map of the Abell 85 Brightest Cluster Galaxy (BCG) was obtained with the Karl G. Jansky Very Large Array (VLA). With a resolution of 0.02", this radio image shows two kiloparsec-scale bipolar jets emanating from the active galactic nucleus of the Abell 85 BCG. The galaxy core appears as a single entity on the new radio map. It has been assumed that the Abell 85 BCG contained a binary black hole in its core. However, Chandra X-ray data and the new high-resolution radio map show no evidence that the Abell 85 BCG harbors a binary black hole. The assumption that this galaxy contains a binary black hole was based on the analysis of its optical surface brightness profile obtained under poor seeing conditions. We demonstrate how the well-known blurring effects of atmospheric seeing can mimic the effects of a binary supermassive black hole (SMBH). Likewise, SDSS J004150.75-091824.3 was postulated to be "a third" SMBH associated with the BCG. In the optical and X-rays, SDSS J004150.75-091824.3 is a point-like source located ~14" away from the nucleus of the Abell 85 BCG. A new spectrum of SDSS J004150.75-091824.3, obtained with the 10.4-m Gran Telescopio Canarias, reveals that this source is a background quasar at a redshift of z=1.560+/-0.003 and not associated in any way with the Abell 85 cluster.