MUSE-ALMA Halos VI: Coupling Atomic, Ionised & Molecular Gas Kinematics
  of Galaxies
  We present results of MUSE-ALMA Halos, an ongoing study of the Circumgalactic
Medium (CGM) of galaxies ($z \leq$ 1.4). Using multi-phase observations we
probe the neutral, ionised and molecular gas in a sub-sample containing six
absorbers and nine associated galaxies in the redshift range $z \sim 0.3-0.75$.
Here, we give an in-depth analysis of the newly CO-detected galaxy Q2131-G1
($z=0.42974$), while providing stringent mass and depletion time limits for the
non-detected galaxies. Q2131-G1 is associated with an absorber with column
densities of $\textrm{log}(N_\textrm{HI}/\textrm{cm}^{-2}) \sim 19.5$ and
$\textrm{log}(N_{\textrm{H}_2}/\textrm{cm}^{-2}) \sim 16.5$, has a star
formation rate of $\textrm{SFR} = 2.00 \pm 0.20 \; \textrm{M}_{\odot}
\textrm{yr}^{-1}$, a dark matter fraction of $f_\textrm{DM}(r_{1/2}) = 0.24 -
0.54$ and a molecular gas mass of $M_\textrm{mol} = 3.52 ^{+3.95}_{-0.31}
\times 10^9 \; \textrm{M}_{\odot}$ resulting in a depletion time of
$\tau_\textrm{dep} < 4.15 \; \textrm{Gyr}$. Kinematic modelling of both the CO
(3--2) and [OIII] $\lambda 5008$ emission lines of Q2131-G1 shows that the
molecular and ionised gas phases are well aligned directionally and that the
maximum rotation velocities closely match. These two gas phases within the disk
are strongly coupled. The metallicity, kinematics and orientation of the atomic
and molecular gas traced by a two-component absorption feature is consistent
with being part of the extended rotating disk with a well-separated additional
component associated with infalling gas. Compared to emission-selected samples,
we find that HI-selected galaxies have high molecular gas masses given their
low star formation rate. We consequently derive high depletion times for these
objects.
