A Study of Selection Methods for H alpha Emitting Galaxies at z~1.3 for
  the Subaru/FMOS Galaxy Redshift Survey for Cosmology (FastSound)
  The efficient selection of high-redshift emission galaxies is important for
future large galaxy redshift surveys for cosmology. Here we describe the target
selection methods for the FastSound project, a redshift survey for H alpha
emitting galaxies at z=1.2-1.5 using Subaru/FMOS to measure the linear growth
rate f\sigma 8 via Redshift Space Distortion (RSD) and constrain the theory of
gravity. To select ~400 target galaxies in the 0.2 deg^2 FMOS field-of-view
from photometric data of CFHTLS-Wide (u*g'r'i'z'), we test several different
methods based on color-color diagrams or photometric redshift estimates from
spectral energy distribution (SED) fitting. We also test the improvement in
selection efficiency that can be achieved by adding near-infrared data from the
UKIDSS DXS (J). The success rates of H alpha detection with FMOS averaged over
two observed fields using these methods are 11.3% (color-color, optical), 13.6%
(color-color, optical+NIR), 17.3% (photo-z, optical), and 15.1% (photo-z,
optical+NIR). Selection from photometric redshifts tends to give a better
efficiency than color-based methods, although there is no significant
improvement by adding J band data within the statistical scatter. We also
investigate the main limiting factors for the success rate, by using the sample
of the HiZELS H alpha emitters that were selected by narrow-band imaging.
Although the number density of total H alpha emitters having higher H alpha
fluxes than the FMOS sensitivity is comparable with the FMOS fiber density, the
limited accuracy of photometric redshift and H alpha flux estimations have
comparable effects on the success rate of <~20% obtained from SED fitting.
