PI: Bradford Holden, UCO/Lick Observatories, firstname.lastname@example.org
Address: Astronomy Department, ISB 1156 High Street, Santa Cruz, CA 95060, USA
CoI: Daniel Kelson, OCIW
CoI: Garth Illingworth, UCO/Lick Observatories
CoI: Marijn Franx, Leiden Observatory
Title: Galaxy Populations from Cluster Infall Regions to the Core at z~1
Abstract: One of the great puzzles of galaxy formation is the apparent dichotomy between star formation and morphological evolution for cluster members. Over the redshift range of z=1 to z=0, the cluster morphological mix appears to change significantly, yet the elliptical and S0s galaxies are uniformly comprised of old, red stellar populations. We are studying the infall regions of three rich, X-ray luminous clusters between z=0.8 - 0.9, MS 1054-03, RX J1052-13, and Cl J1226.9+3332. This latter cluster is the current focus of our observational program. Our observations will test if the progenitors of red cluster galaxies actually form in the outskirts of the cluster through the merging of infalling groups, and to see if the infall or merger process is responsible for the truncation of star formation. A key component of all of this is what are the stellar populations and stellar masses of the infalling galaxies. High quality near-infrared photometry is the linchpin of these measurements, to provide photometric redshifts, galaxy stellar masses, and rest-frame J band selection in Cl J1226.9+3332.
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