CANDELS Sheds Light on the Environmental Quenching of Low‐mass Galaxies
Résumé
We investigate the environmental quenching of galaxies, especially those with stellar masses (M‐*) < 10(9.5) Me‐circle dot, 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 greater than or similar to 1.5. For each low‐mass galaxy, we measure the projected distance (d(proj)) to its nearest massive neighbor (M‐* > 10(10.5) M‐circle dot) 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 10(8) M‐circle dot < M‐* < 10(10) M‐circle dot, such a difference between d(proj)(Q) and d(proj)(SF) is detected up to z similar to 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‐* less than or similar to 10(9.5) M‐circle dot, but increases with satellite M‐* at M‐* greater than or similar to 10(9.5) M‐circle dot. This trend suggests a smooth, if any, transition of the quenching timescale around M‐* similar to 10(9.5) M‐circle dot at 0.5 < z < 1.0.
Domaines
Astrophysique [astro-ph]
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