Abell 267 BCG

Lore & Background

Abell 267 BCG was first discovered in January 1993 by astronomers. It resides as the brightest cluster galaxy in the fossil galaxy cluster Abell 267, with a redshift of 0.229. When observed with the Very Large Array (VLA) at six centimeters, it displays no signs of any associated radio emission, making it technically radio-quiet, with total radio power estimated at less than 23.55 W Hz−1. The BCG also shows an absence of emission lines in its own optical spectrum, and no radio flux was detected based on optical follow-up studies.

The core of the BCG has a red appearance based on its inner color profile shape. Its projected offset relative to the X-ray emission peak of the cluster is estimated at 77.5 kiloparsecs. A study published in 2012 found it belongs to a fossil galaxy cluster and determined its R-band magnitude as 15.72, with an effective surface brightness of 19.50 ± 0.12 magnitudes per arcsecond square. The supermassive black hole at its center has an estimated mass of 2.11 × 10^9 M☉, and the galaxy's rotation is estimated at 0.05 ± 0.06 Vmax with a central velocity dispersion of 321 ± 8 km/s.

Evidence suggests the BCG has an unresolved radio source based on VLA observations at 1.4 GHz frequencies, with total radio luminosity less than 21.3 × 10^38 keV s−1 Hz−1. The radio core imaged at 10 GHz has an upper limit of less than 0.18 mJy with a flat normalization of 0.29. A study published in 2016 found the BCG has an intermediate stellar population of stars aged 4,070 ± 130 and 4,010 ± 200 million years respectively. Its total stellar mass is calculated as 12.42+0.01−0.02 M☉ with a stellar velocity dispersion of 297 ± 16 km/s, and the total ultraviolet star formation rate is estimated at 2.86 M☉ per year.

Reader's Guide

Abell 267 BCG is significant as a massive type-cD galaxy that serves as the brightest cluster galaxy in a fossil galaxy cluster, a rare type of cluster dominated by a single giant elliptical. Its radio-quiet nature, with no detected radio emission at six centimeters and an absence of emission lines, distinguishes it from many other BCGs that often host active radio jets. The galaxy's red core and unresolved radio source at 1.4 GHz suggest a quiescent central engine, while the estimated supermassive black hole mass of 2.11 × 10^9 M☉ and intermediate stellar population ages around 4 billion years provide insights into its evolutionary history. The measured offset of 77.5 kiloparsecs from the cluster's X-ray peak hints at past dynamical interactions. Its legacy lies in offering a case study of a fossil group BCG that is both massive and radio-quiet, contributing to understanding galaxy formation in dense environments.

Did You Know?

• It has a supermassive black hole with an estimated mass of 2.11 × 10^9 M☉.
• The galaxy is radio-quiet, with total radio power less than 23.55 W Hz−1.
• Its stellar population is intermediate-aged, around 4,070 and 4,010 million years.