GEMS Imaging of Red-Sequence Galaxies at z~0.7: Dusty or Old?
Bell, Eric F.; Somerville, Rachel S.; Wisotzki, Lutz; Wolf, Christian; Rix, Hans-Walter; Jogee, Shardha; Barden, Marco; Borch, Andrea; Beckwith, Steven V. W.; Caldwell, John A. R.; McIntosh, Daniel H.; Jahnke, Knud; Meisenheimer, Klaus; Sanchez, Sebastian F.; Peng, Chien; Häussler, Boris
Germany, United States, United Kingdom
Abstract
We have used the 30'×30' Hubble Space Telescope image mosaic from the Galaxy Evolution from Morphology and Spectral energy distributions (GEMS) project in conjunction with the COMBO-17 deep photometric redshift survey to define a sample of nearly 1500 galaxies with 0.65<=z<=0.75. With this sample, we can study the distribution of rest-frame V-band morphologies more than 6 Gyr ago, without differential bandpass shifting and surface brightness dimming across this narrow redshift slice. Focusing on red-sequence galaxies at z~0.7, we find that 85% of their combined rest-frame V-band luminosity density comes from visually classified E/S0/Sa galaxies down to MV-5logh<~-19.5. Similar results are obtained if automated classifiers are used. This fraction is identical to that found at the present day and is biased by less than 10% by large-scale structure and the morphology-density relation. Under the assumption that peculiar and edge-on disk galaxies are red by virtue of their dust content, we find that less than 13% of the total rest-frame V-band luminosity of the z~0.7 red galaxy population is from dusty galaxies.