The detection of a red sequence of massive field galaxies at z∼2.3 and its evolution to z∼0

The existence of massive galaxies with strongly suppressed star formation at z similar to 2.3, identified in a previous paper, suggests that a red sequence may already be in place beyond z = 2. In order to test this hypothesis, we study the rest-frame U - B color distribution of massive galaxies at 2 < z < 3. The sample is drawn from our near-infrared spectroscopic survey for massive galaxies. The color distribution shows a statistically significant (> 3 sigma) red sequence, which hosts similar to 60% of the stellar mass at the high-mass end. The red-sequence galaxies have little or no ongoing star formation, as inferred from both emission-line diagnostics and stellar continuum shapes. Their strong Balmer breaks and their location in the rest-frame U - B, B - V plane indicate that they are in a poststarburst phase, with typical ages of similar to 0.5-1.0 Gyr. In order to study the evolution of the red sequence, we compare our sample with spectroscopic massive galaxy samples at 0.02 < z < 0.045 and 0.6 < z < 1.0. The rest-frame U - B color reddens by similar to 0.25 mag from z similar to 2.3 to the present at a given mass. Over the same redshift interval, the number and stellar mass density on the high-mass end (>10(11)M(circle dot)) of the red sequence grow by factors of similar to 8 and similar to 6, respectively. We explore simple models to explain the observed evolution. Passive evolution models predict too-strong Delta(U - B) and produce z similar to 0 galaxies that are too red. More complicated models that include aging, galaxy transformations, and red mergers can explain both the number density and color evolution of the massive end of the red sequence between z similar to 2.3 and the present.