ASSEMBLY OF THE RED SEQUENCE IN INFRARED-SELECTED GALAXY CLUSTERS FROM THE IRAC SHALLOW CLUSTER SURVEY
- Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
- Department of Physics and Astronomy, University of Missouri, Kansas City, MO 64110 (United States)
- Department of Astronomy, University of Florida, Gainesville, FL 32611 (United States)
- Department of Physics, University of California, One Shields Avenue, Davis, CA 95616 (United States)
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)
- School of Physics, Monash University, Victoria 3800 (Australia)
- NOAO, 950 North Cherry Avenue, Tucson, AZ 85719 (United States)
- E. O. Lawrence Berkeley National Laboratory, University of California, 1 Cyclotron Road, Berkeley, CA 94720 (United States)
We present results for the assembly and star formation histories (SFHs) of massive ({approx}L*) red sequence galaxies (RSGs) in 11 spectroscopically confirmed, infrared-selected galaxy clusters at 1.0 < z < 1.5, the precursors to present-day massive clusters with M {approx} 10{sup 15} M{sub Sun }. Using rest-frame optical photometry, we investigate evolution in the color and scatter of the RSG population, comparing with models of possible SFHs. In contrast to studies of central cluster galaxies at lower redshift (z < 1), these data are clearly inconsistent with the continued evolution of stars formed and assembled primarily at a single, much earlier time. Specifically, we find that the colors of massive cluster galaxies at z Almost-Equal-To 1.5 imply that the bulk of star formation occurred at z {approx} 3, whereas by z Almost-Equal-To 1 their colors imply formation at z {approx} 2; therefore these galaxies exhibit approximately the same luminosity-weighted stellar age at 1 < z < 1.5. This likely reflects star formation that occurs over an extended period, the effects of significant progenitor bias, or both. Our results generally indicate that massive cluster galaxy populations began forming a significant mass of stars at z {approx}> 4, contained some red spheroids by z Almost-Equal-To 1.5, and were actively assembling much of their final mass during 1 < z < 2 in the form of younger stars. Qualitatively, the slopes of the cluster color-magnitude relations are consistent with no significant evolution relative to local clusters.
- OSTI ID:
- 22092398
- Journal Information:
- Astrophysical Journal, Vol. 756, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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