Structural analysis of the Sextans dwarf spheroidal galaxy
  We present wide-field $g$ and $i$ band stellar photometry of the Sextans
dwarf spheroidal galaxy and its surrounding area out to four times its
half-light radius ($r_h=695\,$pc), based on images obtained with the Dark
Energy Camera at the 4-m Blanco telescope at CTIO. We find clear evidence of
stellar substructure associated with the galaxy, extending to a distance of
$82\arcmin$ (2\,kpc) from its centre. We perform a statistical analysis of the
over-densities and find three distinct features, as well as an extended
halo-like structure, to be significant at the $99.7\%$ confidence level or
higher. Unlike the extremely elongated and extended substructures surrounding
the Hercules dwarf spheroidal galaxy, the over-densities seen around Sextans
are distributed evenly about its centre, and do not appear to form noticeable
tidal tails. Fitting a King model to the radial distribution of Sextans stars
yields a tidal radius $r_t =83.2\arcmin\pm7.1\arcmin$ (2.08$\pm$0.18\,kpc),
which implies the majority of detected substructure is gravitationally bound to
the galaxy. This finding suggests that Sextans is not undergoing significant
tidal disruption from the Milky Way, supporting the scenario in which the orbit
of Sextans has a low eccentricity.
