Structure and morphology of the MATLAS dwarf galaxies and their central
  nuclei
  We present a photometric study of the dwarf galaxy population in the low to
moderate density environments of the MATLAS (Mass Assembly of early-Type
gaLAxies with their fine Structures) deep imaging survey. The sample consists
of 2210 dwarfs, including 508 nucleated. We define a nucleus as a compact
source that is close to the galaxy photocentre (within 0.5 $R_e$) which is also
the brightest such source within the galaxy's effective radius. The
morphological analysis is performed using a 2D surface brightness profile
modelling on the g-band images of both the galaxies and nuclei. Our study
reveals that, for similar luminosities, the MATLAS dwarfs show ranges in the
distribution of structural properties comparable to cluster (Virgo and Fornax)
dwarfs and a range of sizes comparable to the Local Group and Local Volume
dwarfs. Colour measurements using the r- and i-band images indicate that the
dwarfs in low and moderate density environments are as red as cluster dwarfs on
average. The observed similarities between dwarf ellipticals in vastly
different environments imply that dEs are not uniquely the product of
morphological transformation due to ram-pressure stripping and galaxy
harassment in high density environments. We measure that the dwarf nuclei are
located predominantly in massive, bright and round dwarfs and observe fewer
nuclei in dwarfs with a faint centre and a small size. The colour of the galaxy
nucleus shows no clear relation to the colour of the dwarf, in agreement with
the migration and wet migration nucleus formation scenarios. The catalogues of
the MATLAS dwarfs photometric and structural properties are provided.
