Observational signatures of a warped disk associated with cold-flow
  accretion
  We present MUSE observations of the field of the quasar Q0152$-$020 whose
spectrum shows a Lyman limit system (LLS) at redshift $z_{\rm abs} = 0.38$,
with a metallicity Z $\gtrsim 0.06$ Z$_\odot$. The low ionization metal lines
associated with the LLS present two narrow distinct absorption components with
a velocity separation of 26 km ${\rm s}^{-1}$. We detect six galaxies within
600 km ${\rm s}^{-1}$ from the absorption redshift; their projected distances
from the quasar sightline range from 60 to 200 kpc. The optical spectra of five
of these galaxies exhibit prominent nebular emission lines, from which we
deduce extinction-corrected star formation rates in the range SFR = 0.06-1.3
M$_\odot$~yr$^{-1}$, and metallicities between 0.2 Z$_\odot$ and Z$_\odot$. The
sixth galaxy is only detected in the stellar continuum. By combining our data
with archival Keck/HIRES spectroscopy of the quasar and HST/WFPC2 imaging of
the field, we can relate absorption line and galaxy kinematics; we conclude
that the LLS is most likely associated with the galaxy closest to the quasar
sight-line (galaxy "a"). Our morphokinematic analysis of galaxy "a" combined
with the absorption line kinematics supports the interpretation that one of the
absorption components originates from an extension of the stellar disk of
galaxy "a", while the other component may arise in accreting gas in a warped
disk with specific angular momentum $\sim 3$ times larger than the specific
angular momentum of the galaxy halo. Such warped disks are common features in
hydrodynamical simulations of cold-flow accretion onto galaxies; the data
presented here provide observational evidence in favour of this scenario.
