The dwarf galaxy satellite system of Centaurus A
  Dwarf galaxy satellite systems are essential probes to test models of
structure formation, making it necessary to establish a census of dwarf
galaxies outside of our own Local Group. We present deep FORS2 VI band images
from the ESO Very Large Telescope for 15 dwarf galaxy candidates in the
Centaurus group of galaxies. We confirm nine dwarfs to be members of CenA by
measuring their distances using a Bayesian approach to determine the tip of the
red giant branch luminosity. We have also fitted theoretical isochrones to
measure their mean metallicities. The properties of the new dwarfs are similar
to those in the Local Group in terms of their sizes, luminosities, and mean
metallicities. Within our photometric precision there is no evidence of a
metallicity spread, but we do observe possible extended star formation in
several galaxies, as evidenced by a population of asymptotic giant branch stars
brighter than the red giant branch tip. The new dwarfs do not show any signs of
tidal disruption. Together with the recently reported dwarf galaxies by the
complementary PISCeS survey, we study the luminosity function and 3D structure
of the group. By comparing the observed luminosity function to the
high-resolution cosmological simulation IllustrisTNG, we find agreement within
a 90% confidence interval. However, CenA seems to be missing its brightest
satellites and has an overabundance of the faintest dwarfs in comparison to its
simulated analogs. In terms of the overall 3D distribution of the observed
satellites, we find that the whole structure is flattened along the
line-of-sight, with an root-mean-square (rms) height of 130 kpc and a rms semi
major axis length of 330 kpc. Future distance measurements of the remaining
dwarf galaxy candidates are needed to complete the census of dwarf galaxies in
the Centaurus group.
