2008/02/29 by Chris Bildfell, C. Bildfell, H. Hoekstra +5 · 4 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Cluster (spacecraft) #Galaxies: Formation, Evolution, Phenomena #Galaxy #Metallicity #Photometry (optics) #Star formation #Stellar, planetary, and galactic studies #Surface brightness #astro-ph
paper · pdf · doi:10.1111/j.1365-2966.2008.13699.x
20 pages, 11 figures, 3 tables. Accepted to MNRAS Updated text in Introduction and Conclusion Sections
arxiv created 2008/07/08 · openalex publication_date 2008/08/26 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We present measurements of surface brightness and colour profiles for the brightest cluster galaxies (BCGs) in a sample of 48 X-ray luminous galaxy clusters. These data were obtained as part of the Canadian Cluster Comparison Project (CCCP). The Kormendy relation of our BCGs is steeper than that of the local ellipticals, suggesting differences in the assembly history of these types of systems. We also find that while most BCGs show monotonic colour gradients consistent with a decrease in metallicity with radius, 25 per cent of the BCGs show colour profiles that turn bluer towards the centre (blue cores). We interpret this bluing trend as evidence for recent star formation. The excess blue light leads to a typical offset from the red sequence of 0.5 to 1.0 mag in (g′−r′), thus affecting optical cluster studies that may reject the BCG based on colour. All of the blue-core BCGs are located within ∼10 kpc of the peak in the cluster X-ray emission. Furthermore, virtually all of the BCGs with recent star formation are in clusters that lie above the Lx–Tx relation. Based on photometry alone, these findings suggest that central star formation is a ubiquitous feature of BCGs in dynamically relaxed cool-core clusters. This implies that while active galactic nuclei (AGNs) and other heating mechanisms are effective at tempering cooling, they do not full compensate for the energy lost via radiation.