What drives galaxy quenching? A deep connection between galaxy kinematics and quenching in the local Universe

Kavli Affiliate: Roberto Maiolino

| First 5 Authors: Simcha Brownson, Asa F. L. Bluck, Roberto Maiolino, Gareth C. Jones,

| Summary:

We develop a 2D inclined rotating disc model, which we apply to the stellar
velocity maps of 1862 galaxies taken from the MaNGA survey (SDSS public Data
Release 15). We use a random forest classifier to identify the kinematic
parameters that are most connected to galaxy quenching. We find that kinematic
parameters that relate predominantly to the disc (such as the mean rotational
velocity) and parameters that characterise whether a galaxy is rotation- or
dispersion-dominated (such as the ratio of rotational velocity to velocity
dispersion) are not fundamentally linked to the quenching of star formation.
Instead, we find overwhelmingly that it is the absolute level of velocity
dispersion (a property that relates primarily to a galaxy’s bulge/spheroidal
component) that is most important for separating star forming and quenched
galaxies. Furthermore, a partial correlation analysis shows that many commonly
discussed correlations between galaxy properties and quenching are spurious,
and that the fundamental correlation is between quenching and velocity
dispersion. In particular, we find that at fixed velocity dispersion, there is
only a very weak dependence of quenching on the disc properties, whereby more
discy galaxies are slightly more likely to be forming stars. By invoking the
tight relationship between black hole mass and velocity dispersion, and noting
that black hole mass traces the total energy released by AGN, we argue that
these data support a scenario in which quenching occurs by preventive feedback
from AGN. The kinematic measurements from this work are publicly available.

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