Probing Galactic Structure with the Spatial Correlation Function of
  SEGUE G-dwarf Stars
  We measure the two-point correlation function of G-dwarf stars within 1-3 kpc
of the Sun in multiple lines-of-sight using the Schlesinger et al. G-dwarf
sample from the SDSS SEGUE survey. The shapes of the correlation functions
along individual SEGUE lines-of-sight depend sensitively on both the
stellar-density gradients and the survey geometry. We fit smooth disk galaxy
models to our SEGUE clustering measurements, and obtain strong constraints on
the thin- and thick-disk components of the Milky Way. Specifically, we
constrain the values of the thin- and thick-disk scale heights with 3% and 2%
precision, respectively, and the values of the thin- and thick-disk scale
lengths with 20% and 8% precision, respectively. Moreover, we find that a
two-disk model is unable to fully explain our clustering measurements, which
exhibit an excess of clustering at small scales (< 50 pc). This suggests the
presence of small-scale substructure in the disk system of the Milky Way.
