Optimizing baryon acoustic oscillation surveys II: curvature, redshifts,
  and external datasets
  We extend our study of the optimization of large baryon acoustic oscillation
(BAO) surveys to return the best constraints on the dark energy, building on
Paper I of this series (Parkinson et al. 2007). The survey galaxies are assumed
to be pre-selected active, star-forming galaxies observed by their line
emission with a constant number density across the redshift bin. Star-forming
galaxies have a redshift desert in the region 1.6 < z < 2, and so this redshift
range was excluded from the analysis. We use the Seo & Eisenstein (2007)
fitting formula for the accuracies of the BAO measurements, using only the
information for the oscillatory part of the power spectrum as distance and
expansion rate rulers. We go beyond our earlier analysis by examining the
effect of including curvature on the optimal survey configuration and updating
the expected `prior' constraints from Planck and SDSS. We once again find that
the optimal survey strategy involves minimizing the exposure time and
maximizing the survey area (within the instrumental constraints), and that all
time should be spent observing in the low-redshift range (z<1.6) rather than
beyond the redshift desert, z>2. We find that when assuming a flat universe the
optimal survey makes measurements in the redshift range 0.1 < z <0.7, but that
including curvature as a nuisance parameter requires us to push the maximum
redshift to 1.35, to remove the degeneracy between curvature and evolving dark
energy. The inclusion of expected other data sets (such as WiggleZ, BOSS and a
stage III SN-Ia survey) removes the necessity of measurements below redshift
0.9, and pushes the maximum redshift up to 1.5. We discuss considerations in
determining the best survey strategy in light of uncertainty in the true
underlying cosmological model.
