Star Formation in Intermediate Redshift 0.2 < Z < 0.7 Brightest Cluster Galaxies [GA]

We present a multi-wavelength photometric and spectroscopic study of 42 Brightest Cluster Galaxies (BCGs) in two samples of clusters of galaxies chosen for the study of gravitational lensing. The study’s initial sample combines 25 BCGs from the Cluster Lensing and Supernova Survey with Hubble (CLASH) sample and 37 BCGs from the Sloan Giant Arcs Survey (SGAS) with a total redshift range of 0.2 < Z < 0.7. Using archival GALEX, HST, WISE, Herschel, and VLA data we determine the BCGs’ stellar mass, radio power, and star formation rates. The radio power is higher than expected if due to star formation, consistent with the BCGs being AGN-powered radio sources. This suggests that the AGN and star formation are both fueled by cold gas in the host galaxy. The specific star formation rate (sSFR) is low and constant with redshift. The mean sSFR is 9.42 * 10^-12 yr^-1 which corresponds to a mass doubling time of 105 billion years. These findings are consistent with models for hierarchical formation of BCGs which suggest that star formation is no longer a significant channel for galaxy growth for z < 1. Instead, stellar growth (of order a factor of at least 2) during this period is expected to occur mainly via minor dry mergers

Read this paper on arXiv…

K. Cooke, C. ODea, S. Baum, et. al.
Wed, 19 Oct 16

Comments: 11 pages, 9 figures, accepted for publication in the Astrophysical Journal