CANDELS Sheds Light on the Environmental Quenching of Low-mass Galaxies
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2017. The American Astronomical Society. All rights reserved.. We investigate the environmental quenching of galaxies, especially those with stellar masses (M ) < 109.5 M o, beyond the local universe. Essentially all local low-mass quenched galaxies (QGs) are believed to live close to massive central galaxies, which is a demonstration of environmental quenching. We use CANDELS data to test whether or not such a dwarf QG-massive central galaxy connection exists beyond the local universe. For this purpose, we only need a statistically representative, rather than complete, sample of low-mass galaxies, which enables our study to z 1.5. For each low-mass galaxy, we measure the projected distance (d proj) to its nearest massive neighbor (M > 1010.5 M o) within a redshift range. At a given z and M , the environmental quenching effect is considered to be observed if the d proj distribution of QGs () is significantly skewed toward lower values than that of star-forming galaxies (). For galaxies with 108 M o < M < 1010 M o, such a difference between and is detected up to z 1. Also, about 10% of the quenched galaxies in our sample are located between two and four virial radii (R Vir) of the massive halos. The median projected distance from low-mass QGs to their massive neighbors, , decreases with satellite M at M 109.5 M o, but increases with satellite M at M 109.5 M o. This trend suggests a smooth, if any, transition of the quenching timescale around M 109.5 M o at 0.5 < z < 1.0.
