Physical properties of distant red galaxies in the COSMOS/UltraVISTA field
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN
Authors: Ma, Zhongyang; Fang, Guanwen; Kong, Xu; Fan, Lulu
Abstract
We present a study on physical properties for a large distant red galaxy (DRG) sample, using the K-selected multi-band photometry catalog of the COSMOS/UltraVISTA field and the CANDELS near-infrared data. Our sample includes 4485 DRGs with (J - K)(AB) > 1.16 and K-AB < 23.4 mag, and 132 DRGs have HST/WFC3 morphological measurements. The results of nonparametric measurements of DRG morphology are consistent with our rest-frame UVJ color classification; quiescent DRGs are generally compact while star-forming DRGs tend to have extended structures. We find the star formation rate (SFR) and the stellar mass of star-forming DRGs present tight "main sequence" relations in all redshift bins. Moreover, the specific SFR (sSFR) of DRGs increases with redshift in all stellar mass bins and DRGs with higher stellar masses generally have lower sSFRs, which indicates that galaxies were much more active on average in the past, and star formation contributes more to the mass growth of low-mass galaxies than to high-mass galaxies. The infrared-derived SFR dominates the total SFR of DRGs which occupy the high-mass range, implying that the J - K color criterion effectively selects massive and dusty galaxies. DRGs with higher M-* generally have redder (U - V)(rest) colors, and the (U - V)(rest) colors of DRGs become bluer at higher redshifts, suggesting high-mass galaxies have higher internal dust extinctions or older stellar ages and they evolve with time. Finally, we find that DRGs have different overlap among extremely red objects, BzK galaxies, IRAC-selected extremely red objects, and high-z ultraluminous infrared galaxies, indicating that DRGs are not a special population and they can also be selected by other color criteria.
CLUSTERING PROPERTIES OF BzK-SELECTED GALAXIES IN GOODS-N: ENVIRONMENTAL QUENCHING AND TRIGGERING OF STAR FORMATION AT z similar to 2
ASTROPHYSICAL JOURNAL
Authors: Lin, Lihwai; Dickinson, Mark; Jian, Hung-Yu; Merson, A. I.; Baugh, C. M.; Scott, Douglas; Foucaud, Sebastien; Wang, Wei-Hao; Yan, Chi-Hung; Yan, Hao-Jing; Cheng, Yi-Wen; Guo, Yicheng; Helly, John; Kirsten, Franz; Koo, David C.; Lagos, Claudia del P.; Meger, Nicole; Messias, Hugo; Pope, Alexandra; Simard, Luc; Grogin, Norman A.; Wang, Shiang-Yu
Abstract
Using a sample of BzK-selected galaxies at z similar to 2 identified from the CFHT/WIRCAM near-infrared survey of GOODS-North, we discuss the relation between star formation rate (SFR), specific star formation rate (SSFR), and stellarmass (M-*), and the clustering of galaxies as a function of these parameters. For star-forming galaxies (sBzKs), the UV-based SFR, corrected for extinction, scales with the stellar mass as SFR proportional to M-*(alpha) with alpha = 0.74 +/- 0.20 down to M-* similar to 10(9) M-circle dot, indicating a weak dependence on the stellar mass of the SFR efficiency, namely, SSFR. We also measure the angular correlation function and hence infer the correlation length for sBzK galaxies as a function of M-*, SFR, and SSFR, as well as K-band apparent magnitude. We show that passive galaxies (pBzKs) are more strongly clustered than sBzK galaxies at a given stellar mass, mirroring the color-density relation seen at lower redshifts. We also find that the correlation length of sBzK galaxies ranges from 4 to 20 h(-1) Mpc, being a strong function of M-K, M-*, and SFR. On the other hand, the clustering dependence on SSFR changes abruptly at 2 x 10(-9) yr(-1), which is the typical value for "main-sequence" star-forming galaxies at z similar to 2. We show that the correlation length reaches a minimum at this characteristic value, and is larger for galaxies with both smaller and larger SSFRs; a dichotomy that is only marginally implied from the predictions of the semi-analytical models. Our results suggest that there are two types of environmental effects at work at z similar to 2. Stronger clustering for relatively quiescent galaxies implies that the environment has started to play a role in quenching star formation. At the same time, stronger clustering for galaxies with elevated SSFRs ("starbursts") might be attributed to an increased efficiency for galaxy interactions and mergers in dense environments.