BCG

Brightest cluster galaxy

Cosmology Galaxies Cluster
Brightest cluster galaxy

brightest galaxy within a cluster

A brightest cluster galaxy (BCG) is defined as the brightest galaxy in a cluster of galaxies. BCGs include the most massive galaxies in the universe. They are generally elliptical galaxies which lie close to the geometric and kinematical center of their host galaxy cluster, hence at the bottom of the cluster potential well. They are also generally coincident with the peak of the cluster X-ray emission.

Read on Wikipedia License Image-Source