CANDELS Sheds Light on the Environmental Quenching of Low-mass Galaxies
Papovich, Casey; Pérez-González, Pablo G.; Santini, Paola; Bell, Eric F.; Ferguson, Henry C.; Fontana, Adriano; Giavalisco, Mauro; Kocevski, Dale D.; Koekemoer, Anton M.; Faber, S. M.; Dekel, Avishai; Koo, David C.; Lee, Seong-Kook; Lu, Yu; Guo, Yicheng; Nayyeri, Hooshang; Pforr, Janine; Kurczynski, Peter; Rodríguez-Puebla, Aldo; Chen, Zhu
United States, South Korea, China, Israel, Italy, Spain, France, Netherlands, Mexico
Abstract
We investigate the environmental quenching of galaxies, especially those with stellar masses (M *) < 109.5 M ⊙, 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 ⊙) 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 ({d}{proj}Q) is significantly skewed toward lower values than that of star-forming galaxies ({d}{proj}{SF}). For galaxies with 108 M ⊙ < M * < 1010 M ⊙, such a difference between {d}{proj}Q and {d}{proj}{SF} 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, {d}{proj}Q/{R}{Vir}, decreases with satellite M * at M * ≲ 109.5 M ⊙, but increases with satellite M * at M * ≳ 109.5 M ⊙. This trend suggests a smooth, if any, transition of the quenching timescale around M * ∼ 109.5 M ⊙ at 0.5 < z < 1.0.