To understand how the present day universe came to be, we must understand how the massive structures in which we live formed and evolved over the preceding billions of years. Constraining how galaxies grow are the most massive galaxies, called brightest cluster galaxies (BCGs). These luminous and diffuse elliptical galaxies inhabit relaxed positions within their host cluster's gravitational potentials and provide a look at the high mass extreme of galaxy evolution. The relaxed structure, old stellar populations, and central location within the cluster indicate a high redshift formation scenario, however, star-forming BCGs have been observed at much more recent epochs. Addressing this evolutionary complexity, my dissertation consists of four studies to investigate the growth rates of BCGs over several epochs, and how they relate to the growth of the general galaxy population. In my first paper, I present a multiwavelength (far-ultraviolet to far-infrared) study of BCG star formation rates and stellar masses from 0.2 < z < 0.7 (Cooke et al. 2016), selected from the CLASH and SGAS surveys. I find that in-situ star formation in my sample is consistent with overall quiescence, and star-forming BCGs remain very rare. In my second paper (Cooke et al. 2018), my sample's redshift range is expanded to z ~ 1 with the addition of massive BCGs (M_Stellar > 10^11 M_Solar) from galaxy clusters available in the COSMOS X-ray Group Catalog. I find that star formation is roughly constant in our sample of high mass BCGs from 0.3 < z < 1.0, with a possible decrease at lower redshifts. We also find a growth rate of ~1% yr^-1, inconsistent with portions of the literature that find an order of magnitude higher growth from infrared selected samples. My third paper (Cooke et al. 2019) identifies BCG progenitors out to z ~ 3 using cumulative comoving number density tracks from the Illustris Project. We identify three phases of growth, limiting the star-formation dominated epoch to z > 2.25. Finally, my fourth paper (Cooke et al. in preparation) places the preceding results in context by measuring the correlation between star formation rate and stellar mass for all galaxies above the COSMOS mass completeness limit from 0 < z < 3.5.
Astrophysical Sciences and Technology (Ph.D.)
Department, Program, or Center
School of Physics and Astronomy (COS)
Cooke, Kevin Christopher, "Magnificent Constructions: The Role of Environment on the Stellar Mass Growth of Massive Galaxies" (2019). Thesis. Rochester Institute of Technology. Accessed from
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