The SPLASH Survey: Internal Kinematics, Chemical Abundances, and Masses
  of the Andromeda I, II, III, VII, X, and XIV dSphs
  We present new Keck/DEIMOS spectroscopic observations of hundreds of
individual stars along the sightline to Andromeda's first three discovered
dwarf spheroidal galaxies (dSphs) - And I, II, and III, and leverage recent
observations by our team of three additional dSphs, And VII, X, and XIV, as a
part of the SPLASH Survey. Member stars of each dSph are isolated from
foreground Milky Way dwarf and M31 field contamination using a variety of
photometric and spectroscopic diagnostics. Our final spectroscopic sample of
member stars in each dSph, for which we measure accurate radial velocities with
a median uncertainty (random plus systematic errors) of 4 - 5 km/s, includes 80
red giants in And I, 95 in And II, 43 in And III, 18 in And VII, 22 in And X,
and 38 in And XIV. The sample of confirmed members in the six dSphs are used to
derive each system's mean radial velocity, intrinsic central velocity
dispersion, mean abundance, abundance spread, and dynamical mass. This combined
data set presents us with a unique opportunity to perform the first systematic
comparison of the global properties (e.g., metallicities, sizes, and dark
matter masses) of one-third of Andromeda's total known dSph population with
Milky Way counterparts of the same luminosity. We discuss both the
luminosity-metallicity relation and the luminosity-size relation of these
satellites, and find that the chemical evolution histories of each host's
satellites is similar. The dynamical mass estimates of M31's dSphs are similar
or smaller than Milky Way dSphs of the same luminosity despite their sizes
being similar or larger, suggesting M31 dSphs are less dense than Milky Way
counterparts. The implications of these results for general understanding of
galaxy formation and evolution is summarized. Abridged.
