The Fossil Record of Two-phase Galaxy Assembly: Kinematics and
  Metallicities in the Nearest S0 Galaxy
  We present a global analysis of kinematics and metallicity in the nearest S0
galaxy, NGC 3115, along with implications for its assembly history. The data
include high-quality wide-field imaging from Suprime-Cam on the Subaru
telescope, and multi-slit spectra of the field stars and globular clusters
(GCs) obtained using Keck-DEIMOS/LRIS and Magellan-IMACS. Within two effective
radii, the bulge (as traced by the stars and metal-rich GCs) is flattened and
rotates rapidly (v/sigma > 1.5). At larger radii, the rotation declines
dramatically to v/sigma ~ 0.7, but remains well-aligned with the inner regions.
The radial decrease in characteristic metallicity of both the metal-rich and
metal-poor GC subpopulations produces strong gradients with power law slopes of
-0.17 +/- 0.04 and -0.38 +/- 0.06 dex per dex, respectively. We argue that this
pattern is not naturally explained by a binary major merger, but instead by a
two-phase assembly process where the inner regions have formed in an early
violent, dissipative phase, followed by the protracted growth of the outer
parts via minor mergers with typical mass ratios of ~ 15-20:1.
