A Collection of New Dwarf Galaxies in NGC5128's Western Halo
  We report the photometric properties of 16 dwarf galaxies, 15 of which are
newly identified, in the Western halo of the nearby giant elliptical galaxy
NGC5128. All candidates are found at projected distances $\sim\!100\!-\!225$kpc
from their giant host, with luminosities $-10.82\!\leq\!M_V/{\rm
mag}\!\leq\!-7.42$ and effective radii $4''\!\leq\!r_{\rm eff}\!\leq\!17''$ (or
$75\!\leq\!r_{\rm eff}/{\rm pc}\!\leq\!300$ at the distance of NGC5128). We
compare to other low-mass dwarf galaxies in the local universe and find them to
populate the faint/compact extension of the size-luminosity relation that was
previously not well-sampled by dwarf galaxies in the Centaurus A system, with
optical colors similar to compact stellar systems like globular clusters and
ultra-compact dwarf galaxies despite having much more diffuse morphologies.
From optical $u'g'r'i'z'$ photometry, stellar masses are estimated to be
$5.17\!\leq\!\log{\cal M}_\star/M_\odot\!\leq\!6.48$, with colors that show
them to fall redward of the dwarf galaxy mass-metallicity relation. These
colors suggest star formation histories that require some mechanism that would
give rise to extra metal enrichment such as primordial formation within the
halos of their giant galaxy hosts, non-primordial star formation from
previously enriched gas, or extended periods of star formation leading to
self-enrichment. We also report the existence of at least two sub-groups of
dwarf candidates, each subtending $10-20'$ on the sky, corresponding to
projected physical separations of $10\!-\!20$kpc. True physical associations of
these groups, combined with their potentially extended star formation
histories, would imply that they may represent dwarf galaxy groups in the early
stage of interaction upon infall into a giant elliptical galaxy halo in the
very nearby universe.
