The Dark Energy Survey view of the Sagittarius stream: discovery of two
  faint stellar system candidates
  We report the discovery of two new candidate stellar systems in the
constellation of Cetus using the data from the first two years of the Dark
Energy Survey (DES). The objects, DES J0111-1341 and DES J0225+0304, are
located at a heliocentric distance of ~ 25 kpc and appear to have old and
metal-poor populations. Their distances to the Sagittarius orbital plane, ~
1.73 kpc (DES J0111-1341) and ~ 0.50 kpc (DES J0225+0304), indicate that they
are possibly associated with the Sagittarius dwarf stream. The half-light
radius (r_h ~ 4.55 pc) and luminosity (M_V ~ +0.3) of DES J0111-1341 are
consistent with it being an ultrafaint stellar cluster, while the half-light
radius (r_h ~ 18.55 pc) and luminosity (M_V ~ -1.1) of DES J0225+0304 place it
in an ambiguous region of size-luminosity space between stellar clusters and
dwarf galaxies. Determinations of the characteristic parameters of the
Sagittarius stream, metallicity spread (-2.18 < [Fe/H] < -0.95) and distance
gradient (23 kpc < D_sun < 29 kpc), within the DES footprint in the Southern
hemisphere, using the same DES data, also indicate a possible association
between these systems. If these objects are confirmed through spectroscopic
follow-up to be gravitationally bound systems and to share a Galactic
trajectory with the Sagittarius stream, DES J0111-1341 and DES J0225+0304 would
be the first ultrafaint stellar systems associated with the Sagittarius stream.
Furthermore, DES J0225+0304 would also be the first confirmed case of an
ultrafaint satellite of a satellite.
