New low surface brightness dwarf galaxies in the Centaurus group
  We conducted an extensive CCD search for faint, unresolved dwarf galaxies of
very low surface brightness in the whole Centaurus group region encompassing
the Cen A and M 83 subgroups lying at a distance of roughly 4 and 5 Mpc,
respectively. The aim is to significantly increase the sample of known
Centaurus group members down to a fainter level of completeness, serving as a
basis for future studies of the 3D structure of the group. Following our
previous survey of 60 square degrees covering the M 83 subgroup, we extended
and completed our survey of the Centaurus group region by imaging another 500
square degrees area in the g and r bands with the wide-field Dark Energy Survey
Camera at the 4m Blanco telescope at CTIO. The limiting central surface
brightness reached for suspected Centaurus members is $\mu_r \approx 29$ mag
arcsec$^{-2}$, corresponding to an absolute magnitude $M_r \approx -9.5$. The
images were enhanced using different filtering techniques. We found 41 new
dwarf galaxy candidates, which together with the previously discovered 16 dwarf
candidates in the M 83 subgroup amounts to almost a doubling of the number of
known galaxies in the Centaurus complex, if the candidates are confirmed. We
carried out surface photometry in g and r, and report the photometric
parameters derived therefrom, for all new candidates as well as previously
known members in the surveyed area. The photometric properties of the
candidates, when compared to those of LG dwarfs and previously known Centaurus
dwarfs, suggest membership in the Centaurus group. The sky distribution of the
new objects is generally following a common envelope around the Cen A and M 83
subgroups. How the new dwarfs are connected to the intriguing double-planar
feature recently reported by Tully et al. (2015) must await distance
information for the candidates.
