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Paper: A Keck Spectroscopic Study of MS 105403 (z = 0.83): Forming the Red Sequence
Volume: 379, Cosmic Frontiers
Page: 348
Authors: Tran, K.-V.H.
Abstract: Using a magnitude-limited, spectroscopic survey of the X-ray luminous galaxy cluster MS 105403, we isolate 153 cluster galaxies and measure MS1054s redshift and velocity dispersion to be z = 0.8307 0.0004 and σz = 1156 82 km s−1. The absorption-line, post-starburst (E+A), and emission-line galaxies respectively make up 637%, 154%, and 234% of the cluster population. With photometry from HST/ACS, we find that the absorption-line members define an exceptionally tight red sequence over a span of ~ 3.5 magnitudes in i775: their intrinsic scatter in (V606i775) color is only 0.048 0.008, corresponding to a (U − B)z scatter of 0.041. Their color scatter is comparable to that of the ellipticals (σV i = 0.055 0.008), but measurably smaller than that of the combined E+S0 sample (σV i = 0.072 0.010). The color scatter of MS1054s absorption-line population is approximately twice that of the ellipticals in Coma; this difference is consistent with passive evolution where most of the absorption-line members (> 75%) formed by z ~ 2, and all of them by z ~ 1.2.
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