MeerKAT and the Smallest Galaxies
  (Abridged) On small scales, there exists a tension between observations of
dwarf galaxies and predictions for low-mass dark matter halos from simulations
(often referred to as the small scale crisis). Detailed observations of low
mass galaxies are critical for constraining the baryonic feedback processes
that are used to alleviate these discrepancies. Dwarf galaxies with a
substantial reservoir of neutral hydrogen (HI) are likely to be isolated,
helping to disentangle intrinsic properties from evolutionary effects, and HI
kinematics offer an immediate constraint on the hosting dark matter halo. Given
MeerKAT's exquisite sensitivity, it can potentially contribute to these studies
of low-mass HI-rich dwarf galaxies that will help resolve the small scale
crisis. The current large HI surveys are not designed for these studies, but
will still manage to detect a sample of galaxies with HI masses below 10^7 Msun
comparable to the number of systems currently in the literature, and will
resolve ~15 systems with masses below 10^8.5 Msun, a critical regime for
addressing which dark matter halos host low-mass galaxies. We propose a
thousand hour survey of the Centaurus region, encompassing the M83 and CenA
galaxy groups, which can robustly address the central question: "How many
galaxies equivalent to Leo T are there in the Centaurus region?" Leo T is the
lowest mass, gas-rich galaxy currently known; our proposed survey is designed
to be able to detect an object of similar HI mass and linewidth throughout the
volume of the Centuaurus region, which will provide a full census of how many
objects like this there are in a typical galaxy group. In addition, planes of
satellites have recently been identified around CenA and our survey will be
able to address how far out these planes extend: are they structures
concentrated only around the central galaxy or are they connected to large
scale structure?
