Characteristic mass in galaxy quenching: environmental versus internal effects

Pengfei Li; Huiyuan Wang; H. J. Mo; Enci Wang; Hui Hong

doi:10.3847/1538-4357/abb66c

paper

Characteristic mass in galaxy quenching: environmental versus internal effects

arXiv:2003.09776 · doi:10.3847/1538-4357/abb66c

Abstract

A clear transition feature of galaxy quenching is identified in the multi-parameter space of stellar mass ( $M_{*}$ ), bulge to total mass ratio ( $B / T_{m}$ ), halo mass ( $M_{h}$ ) and halo-centric distance ( $r / r_{180}$ ). For given halo mass, the characteristic stellar mass ( $M_{*, ch}$ ) for the transition is about one-fifth of that of the corresponding central galaxy, and almost independent of $B / T_{m}$ . Once $B / T_{m}$ is fixed, the quenched fraction of galaxies with $M_{*} < M_{*, ch}$ increases with $M_{h}$ , but decreases with $M_{*}$ in the inner part of halos ( $r / r_{180} < 0.5$ ). In the outer part ( $r / r_{180} > 0.5$ ), the trend with $M_{h}$ remains but the correlation with $M_{*}$ is absent or becomes positive. For galaxies above $M_{*, ch}$ and with $B / T_{m}$ fixed, the quenched fraction increases with $M_{*}$ , but depends only weakly on $M_{h}$ in both the inner and outer regions. At fixed $B / T_{m}$ and $M_{*}$ , the quenched fraction increases with decreasing $r / r_{180}$ for galaxies with $M_{*} < M_{*, ch}$ , and depends only weakly on $r / r_{180}$ for galaxies with $M_{*} > M_{*, ch}$ . Our finding provides a physically-motivated way to classify galaxies in halos into two classes based on their quenching properties: an `upper class' with $M_{*} > M_{*, ch}$ and a `lower class' with $M_{*} < M_{*, ch}$ . Environmental quenching is important for `lower class' galaxies, while internal quenching plays the dominating role for the `upper class'.

arXiv comment11 pages, 7 figures, accepted by ApJ

Characteristic mass in galaxy quenching: environmental versus internal effects

Abstract

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