Probing the intra-group medium of a z = 0.28 galaxy group
  We present new MUSE observations of a galaxy group probed by a background
quasar. The quasar sightline passes between multiple $z=0.28$ galaxies, whilst
showing at the same redshift low ionised metal line species, including Ca II,
Mg I, Mg II and Fe II. Based on the galaxy redshifts measured from the MUSE
data, we estimate the galaxies to be part of a small galaxy group with a halo
mass of $\approx6\times10^{12}$ M$_{\odot}$. We use the MUSE data to reveal the
two dimensional dynamical properties of the gas and stars in the group
galaxies, and relate these to the absorber kinematics. With these data we
consider a number of scenarios for the nature of the gas probed by the
sightline absorbers: a co-rotating gas halo associated with a single galaxy
within the group; outflowing material from a single group member powered by
recent star-formation; and cool dense gas associated with an intra-group
medium. We find that the dynamics, galaxy impact parameters, star-formation
rates, and the absorber strength suggest the cool gas can not be clearly
associated with any single galaxy within the group. Instead we find that the
observations are consistent with a superposition of cool gas clouds originating
with the observed galaxies as they fall into the group potential, and are now
likely in the process of forming the intra-group medium.
