M/L{sub B} AND COLOR EVOLUTION FOR A DEEP SAMPLE OF M* CLUSTER GALAXIES AT z {approx} 1: THE FORMATION EPOCH AND THE TILT OF THE FUNDAMENTAL PLANE , ,
- UCO/Lick Observatories, University of California, Santa Cruz, CA 95065 (United States)
- Max-Planck Institute for Astronomy, Koenigstuhl 17, D-69117, Heidelberg (Germany)
- Observatories of the Carnegie Institution of Washington, Pasadena, CA 91101 (United States)
- Sterrewacht Leiden, P.O. Box 9513, 2300 RA, Leiden (Netherlands)
We have measured velocity dispersions ({sigma}) for a sample of 36 galaxies with J < 21.2 or M{sub r} < -20.6 mag in MS 1054-03, a massive cluster of galaxies at z = 0.83. Our data are of uniformly high quality down to our selection limit, our 16 hr exposures typically yielding errors of only {delta}({sigma}) {approx} 10% for L* and fainter galaxies. By combining our measurements with data from the literature, we have 53 cluster galaxies with measured dispersions, and HST/ACS-derived sizes, colors and surface brightness. This sample is complete for the typical L* galaxy at z {approx} 1, unlike most previous z {approx} 1 cluster samples which are complete only for the massive cluster members (>10{sup 11} M{sub sun}). We find no evidence for a change in the tilt of the fundamental plane (FP). Nor do we find evidence for evolution in the slope of the color-{sigma} relation and M/L{sub B} -{sigma} relations; measuring evolution at a fixed {sigma} should minimize the impact of structural evolution found in other work. The M/L{sub B} at fixed {sigma} evolves by {Delta}log{sub 10} M/L{sub B} = -0.50 {+-} 0.03 between z = 0.83 and z = 0.02 or dlog{sub 10} M/L{sub B} = -0.60 {+-} 0.04 dz, and we find {Delta}(U - V){sub z} = -0.24 {+-} 0.02 mag at fixed {sigma} in the rest frame, matching the expected evolution in M/L{sub B} within 2.25 standard deviations. The implied formation redshift from both the color and M/L{sub B} evolution is z{sub *} = 2.0 {+-} 0.2 {+-} 0.3(sys), during the epoch in which the cosmic star formation activity peaked, with the systematic uncertainty showing the dependence of z{sub *} on the assumptions we make about the stellar populations. The lack of evolution in either the tilt of the FP or in the M/L-{sigma} and color-{sigma} relations imply that the formation epoch depends weakly on mass, ranging from z{sub *} = 2.3{sup +1.3}{sub -0.3} at {sigma} = 300 km s{sup -1} to z{sub *} = 1.7{sup +0.3}{sub -0.2} at {sigma} = 160 km s{sup -1} and implies that the initial mass function similarly varies slowly with galaxy mass.
- OSTI ID:
- 21471161
- Journal Information:
- Astrophysical Journal, Vol. 724, Issue 1; Other Information: DOI: 10.1088/0004-637X/724/1/714; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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