http://arxiv.org/abs/1401.7813
From several searches of the area common to the Sloan Digital Sky Survey and the United Kingdom Infrared Telescope Infrared Deep Sky Survey, we have identified objects that have properties similar to those of the luminous quiescent compact galaxies found at z > 2. Here we present our results of 22 galaxies between z ~ 0.4 and z ~ 0.9 based on observations with the Keck I, Keck II and Subaru telescopes on Mauna Kea. By exploring sizes, morphologies, and stellar populations of these galaxies, we found that most of the galaxies we identified actually formed most of their stars at z < 2, where the density of universe was lower than at high redshifts. These young galaxies are less compact than those found at z > 2 in the literature. Several of these young objects appear to be disk-like or possibly prolate. This lines up with several previous studies, which found that massive quiescent galaxies at high redshifts often have disk-like morphologies. If these galaxies were to be confirmed to be disks, their formation would be more likely caused by gas accretion than by major mergers. On the other hand, if these galaxies were to be confirmed to be prolate, the fact that prolate galaxies do not exist in the local universe would indicate that galaxy formation mechanisms have evolved over cosmic time. We also found six galaxies with spectra indicating formation of over 75% of their masses at z > 2. Five of these galaxies appear to have been modified over cosmic time, in agreement with the inside-out buildup of massive galaxies recently proposed in the literature. The remaining galaxy, SDSS J014355.21+133451.4, has a truly old stellar population, a very small size, and a disk-like morphology. This object would be a good candidate for a nearly unmodified compact quiescent galaxy from high redshifts that would be worth future study.
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