Characteristic mass in galaxy quenching: environmental versus internal effects. (arXiv:2003.09776v4 [astro-ph.GA] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Li_P/0/1/0/all/0/1">Pengfei Li</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wang_H/0/1/0/all/0/1">Huiyuan Wang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mo_H/0/1/0/all/0/1">H.J. Mo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wang_E/0/1/0/all/0/1">Enci Wang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hong_H/0/1/0/all/0/1">Hui Hong</a>
A clear transition feature of galaxy quenching is identified in the
multi-parameter space of stellar mass ($M_*$), bulge to total mass ratio
($B/T_{rm m}$), halo mass ($M_{rm h}$) and halo-centric distance
($r/r_{180}$). For given halo mass, the characteristic stellar mass ($M_{*, rm
ch}$) for the transition is about one-fifth of that of the corresponding
central galaxy, and almost independent of $B/T_{rm m}$. Once $B/T_{rm m}$ is
fixed, the quenched fraction of galaxies with $M_*<M_{*, rm ch}$ increases
with $M_{rm h}$, 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 $M_{rm
h}$ remains but the correlation with $M_*$ is absent or becomes positive. For
galaxies above $M_{rm *, ch}$ and with $B/T_{rm m}$ fixed, the quenched
fraction increases with $M_{rm *}$, but depends only weakly on $M_{rm h}$ in
both the inner and outer regions. At fixed $B/T_{rm m}$ and $M_*$, the
quenched fraction increases with decreasing $r/r_{180}$ for galaxies with
$M_*<M_{*, rm ch}$, and depends only weakly on $r/r_{180}$ for galaxies with
$M_*>M_{*, rm ch}$. Our finding provides a physically-motivated way to
classify galaxies in halos into two classes based on their quenching
properties: an `upper class’ with $M_*>M_{rm *,ch}$ and a `lower class’ with
$M_*<M_{rm *,ch}$. Environmental quenching is important for `lower class’
galaxies, while internal quenching plays the dominating role for the `upper
class’.
A clear transition feature of galaxy quenching is identified in the
multi-parameter space of stellar mass ($M_*$), bulge to total mass ratio
($B/T_{rm m}$), halo mass ($M_{rm h}$) and halo-centric distance
($r/r_{180}$). For given halo mass, the characteristic stellar mass ($M_{*, rm
ch}$) for the transition is about one-fifth of that of the corresponding
central galaxy, and almost independent of $B/T_{rm m}$. Once $B/T_{rm m}$ is
fixed, the quenched fraction of galaxies with $M_*<M_{*, rm ch}$ increases
with $M_{rm h}$, 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 $M_{rm
h}$ remains but the correlation with $M_*$ is absent or becomes positive. For
galaxies above $M_{rm *, ch}$ and with $B/T_{rm m}$ fixed, the quenched
fraction increases with $M_{rm *}$, but depends only weakly on $M_{rm h}$ in
both the inner and outer regions. At fixed $B/T_{rm m}$ and $M_*$, the
quenched fraction increases with decreasing $r/r_{180}$ for galaxies with
$M_*<M_{*, rm ch}$, and depends only weakly on $r/r_{180}$ for galaxies with
$M_*>M_{*, rm ch}$. Our finding provides a physically-motivated way to
classify galaxies in halos into two classes based on their quenching
properties: an `upper class’ with $M_*>M_{rm *,ch}$ and a `lower class’ with
$M_*<M_{rm *,ch}$. Environmental quenching is important for `lower class’
galaxies, while internal quenching plays the dominating role for the `upper
class’.
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