New dwarf galaxy candidates in the Centaurus group
  Recent studies of the distribution and kinematics of the Milky Way and
Andromeda satellite galaxy systems have confirmed the existence of coplanar,
corotating structures of galaxies. In addition to the 'missing satellite
problem', these structures pose a major challenge to the standard $\Lambda$CDM
scenario of structure formation. We complement the efforts made by the dwarf
galaxy community to extend these studies to other nearby galaxy groups by
systematically searching for faint, unresolved dwarf members with a low surface
brightness in the Southern Centaurus group of galaxies. The aim is to determine
whether these coplanar, corotating structures are a universal phenomenon. We
imaged an area of 60 square degrees (0.3 Mpc$^2$) around the M83 subgroup with
the wide-field Dark Energy Camera (DECam) at the CTIO 4 m Blanco telescope in
$g$ and $r$ down to a limiting surface brightness of $\mu_r\approx 30$ mag
arcsec$^{-2}$. Various image-filtering techniques were applied to the DECam
data to enhance the visibility of extremely low-surface brightness objects. We
report the discovery of 16 new dwarf galaxy candidates in the direction of the
M83 subgroup, roughly doubling the number of known dwarfs in that region. The
photometric properties of the candidates, when compared to those of the Local
Group, suggest membership in the M83 subgroup. The faintest objects have a
central star density of $\approx1.3 L_\odot$ pc$^{-2}$ and a total magnitude of
$g = 20.25$, corresponding to $M_g = -9.55$ at the nominal distance of 4.9 Mpc.
The sky distribution of the new objects is significantly prolonged toward Cen
A, suggesting that many of them belong to the Cen A subgroup or a common halo.
We also provide updated surface photometry for the brighter, known dwarf
members in the surveyed area.
