The Rise of Massive Red Galaxies: the color-magnitude and color-stellar mass diagrams for z < ~2 from the MUltiwavelength Survey by Yale-Chile (MUSYC)

TL;DR

This study uses multiwavelength survey data to analyze the evolution of massive red galaxies up to redshift 2, revealing significant growth and color changes in the red sequence over cosmic time.

Contribution

It provides the first empirical analysis of the color-magnitude and color-stellar mass relations for galaxies up to z~2, highlighting their evolution and the growth of massive red galaxies.

Findings

Red sequence color-stellar mass relation evolves as ~-0.44 per unit redshift for z<1.2.

At z~1.8, about 50% of local massive galaxies are present.

The red fraction of massive galaxies increases over time, following a power-law evolution.

Abstract

We present the color-magnitude and color-stellar mass diagrams for galaxies with z_phot < ~2, based on a K < 22 (AB) catalog of the Extended Chandra Deep Field South (ECDFS) from the MUltiwavelength Survey by Yale-Chile (MUSYC). Our main sample of 7840 galaxies contains 1297 M_* > 10^11 M_Sol galaxies in the range 0.2 < z_phot < 1.8. We show empirically that this catalog is approximately complete for M_* > 10^11 M_Sol galaxies for z_phot < 1.8. For this mass-limited sample, we show that the locus of the red sequence color-stellar mass relation evolves as Del(u-r) ~ (-0.44+/-0.02) z_phot for z_phot < ~1.2. For z_phot > ~1.3, however, we are no longer able to reliably distinguish red and blue subpopulations from the observed color distribution; we show that this would require much deeper near infrared data. At 1.5 < z_phot <1.8, the comoving number density of M_* > 10^11 M_Sol galaxies is ~50% of the local value, with a red fraction of ~33%. Making a parametric fit to the observed evolution, we find n_tot(z) ~ (1+z_phot)^(-0.52+/-0.12(+/-0.20)). We find stronger evolution in the red fraction: f_red(z) ~ (1+z_phot)^(-1.17+/-0.18(+/-0.21)). Through a series of sensitivity analyses, we show that the most important sources of systematic error are: 1. systematic differences in the analysis of the z~0 and z>>0 samples; 2. systematic effects associated with details of the photometric redshift calculation; and 3. uncertainties in the photometric calibration. With this in mind, we show that our results based on photometric redshifts are consistent with a completely independent analysis which does not require redshift information for individual galaxies. Our results suggest that, at most, 1/5 of local red sequence galaxies with M_* >10^11 M_Sol were already in place at z ~ 2.