Extragalactic Science, Cosmology and Galactic Archaeology with the
  Subaru Prime Focus Spectrograph (PFS)
  The Subaru Prime Focus Spectrograph (PFS) is a massively-multiplexed
fiber-fed optical and near-infrared 3-arm spectrograph (N_fiber=2400,
380<lambda<1260nm, 1.3 degree diameter FoV), offering unique opportunities in
survey astronomy. Here we summarize the science case feasible for a survey of
Subaru 300 nights. We describe plans to constrain the nature of dark energy via
a survey of emission line galaxies spanning a comoving volume of 9.3 (Gpc/h)^3
in the redshift range 0.8<z<2.4. In each of 6 redshift bins, the cosmological
distances will be measured to 3% precision via BAO, and redshift-space
distortions will be used to constrain structure growth to 6% precision. In the
GA program, radial velocities and chemical abundances of stars in the Milky Way
and M31 will be used to infer the past assembly histories of spiral galaxies
and the structure of their dark matter halos. Data will be secured for 10^6
stars in the Galactic thick-disk, halo and tidal streams as faint as V~22,
including stars with V < 20 to complement the goals of the Gaia mission. A
medium-resolution mode with R = 5000 to be implemented in the red arm will
allow the measurement of multiple alpha-element abundances and more precise
velocities for Galactic stars, elucidating the detailed chemo-dynamical
structure and evolution of each of the main stellar components of the Milky Way
Galaxy and of its dwarf spheroidal galaxies. For the extragalactic program, our
simulations suggest the wide avelength range will be powerful in probing the
galaxy population and its clustering over a wide redshift range. We propose to
conduct a color-selected survey of 1<z<2 galaxies and AGN over 16 deg^2 to
J~23.4, yielding a fair sample of galaxies with stellar masses above ~10^{10}Ms
at z~2. A two-tiered survey of higher redshift LBGs and LAEs will quantify the
properties of early systems close to the reionization epoch.
