2004/01/01 by Holland Ford, H. Ford, M. Postman +9 · 1 citation
Physics and Astronomy · #Astronomy and Astrophysical Research #Cluster (spacecraft) #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy cluster #Galaxy groups and clusters #Intracluster medium #Luminosity #Metallicity #Redshift #Scientific Research and Discoveries #Spiral galaxy #astro-ph
paper · pdf · doi:10.1007/978-1-4020-2862-5_42
18 pages, 12 figures, to appear in Penetrating Bars through Masks of Cosmic Dust: the Hubble Tuing Fork Strikes a New Note, eds. D.L. Block, K.C. Freeman, I. Puerari & R. Groess. Figures degraded to meet astroph size limit; a version with higher resolution figures may be downloaded from: http://acs.pha.jhu.edu/~jpb/z1clusters/ford_clusters.pdf
openalex publication_date 2004/01/01 · arxiv created 2004/08/09 · arxiv updated 2016/01/27 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Combined HST, X-ray, and ground-based optical studies show that clusters of galaxies are largely "in place" by z ∼ 1, an epoch when the Universe was less than half its present age. High resolution images show that elliptical, S0, and spiral galaxies are present in clusters at redshifts up to z ∼ 1.3. Analysis of the CMDs suggest that the cluster ellipticals formed their stars several Gyr earlier, near redshift 3. The morphology--density relation is well established at z∼1, with star-forming spirals and irregulars residing mostly in the outer parts of the clusters and E/S0s concentrated in dense clumps. The intracluster medium has already reached the metallicity of present-day clusters. The distributions of the hot gas and early-type galaxies are similar in z∼1 clusters, indicating both have largely virialized in the deepest potentials wells. In spite of the many similarities between z∼1 and present-day clusters, there are significant differences. The morphologies revealed by the hot gas, and particularly the early-type galaxies, are elongated rather than spherical. We appear to be observing the clusters at an epoch when the sub-clusters and groups are still assembling into a single regular cluster. Support for this picture comes from CL0152 where the gas appears to be lagging behind the luminous and dark mass in two merging sub-components. Moreover, the luminosity difference between the first and second brightest cluster galaxies at z∼1 is smaller than in 93% of present-day Abell clusters, which suggests that considerable luminosity evolution through merging has occurred since that epoch. Evolution is also seen in the bolometric X-ray luminosity function.