July 12, 2019

The brightest and most massive galaxies in the universe, the Brightest Cluster Galaxies (BCGs), tell a unique story of galaxy evolution. Today, BCGs are quiescent ellipticals hosted in relaxed galaxy clusters, with pasts fraught with mergers and high star formation rates (SFRs).

In a recent publication, Cooke et al. investigate how this active past may depend on local environment by estimating star formation in BCG progenitors in the COSMOS field out to a redshift of z ~ 3 (more than 11 billion years in the past). To estimate star formation rates, they fit progenitor observations with various models from the far-ultraviolet to far-infrared wavelengths. They find that BCG progenitors gain stellar mass in three phases, with effects due to local environment manifesting at z < 1.25 (9 billion years in the past).

The image shows the stellar mass growth of of galaxies in the field (meaning isolated) in blue and dense environments (meaning in clusters) in red. 

For more information, check out the full paper!