AEGIS: The Diversity of Bright Near-IR-selected Distant Red Galaxies

We use deep and wide near-infrared (NIR) imaging from the Palomar telescope combined with DEEP2 spectroscopy and HST and Chandra imaging to investigate the nature of galaxies that are red in NIR colors. We locate these "distant red galaxies" (DRGs) through the color cut (J - K)Vega > 2.3 over 0.7 deg2, where we find 1010 DRG candidates down to Ks = 20.5. We combine 95 high-quality spectroscopic redshifts with photometric redshifts from BRIJK photometry to determine the redshift and stellar mass distributions for these systems, and the morphological/structural and X-ray properties for 107 DRGs in the Extended Groth Strip. We find that many bright (J - K)Vega > 2.3 galaxies with Ks < 20.5 are at redshifts z < 2, with 64% in the range 1 < z < 2. The stellar mass distributions for these galaxies are broad, ranging from 109 to 1012 M☉, but with most z > 2 systems being massive with M* > 1011 M☉. HST imaging shows that the structural properties and morphologies of DRGs are also diverse, with the majority elliptical/compact (57%) and the remainder edge-on spiral (7%) and peculiar (29%). The DRGs at z < 1.4 with high-quality spectroscopic redshifts are generally compact, with small half-light radii, and span a range in rest-frame optical properties. The spectral energy distribution for the DRGs at z < 1.4 differs from higher redshift DRGs: they are bluer by 1 mag in observed (I - J) color. A pure IR color selection of high-redshift populations is not sufficient to identify unique populations, and other colors or spectroscopic redshifts are needed to produce homogeneous samples.