Extracting Angular Diameter Distance and Expansion Rate of the Universe from Two-dimensional Galaxy Power Spectrum at High Redshifts: Baryon Acoustic Oscillation Fitting versus Full Modeling

We present a method for extracting the angular diameter distances, DA, and the expansion rates, H , of the universe from the two-dimensional Baryon Acoustic Oscillations (BAO) in the galaxy power spectrum. Our method builds upon the existing algorithm called the “fit-and-extract” (FITEX) method, which allows one to extract only D A/H from a spherically averaged one-dimensional power spectrum. We develop the FITEX-2d method, an extension of the FITEX method, to include the twodimensional information, which allows us to extractDA and H simultaneously. We test the FITEX-2d method using the Millennium Simulation as well as simplified Monte Carlo simulations with a bigger volume. The BAOs, however, contain only a limited amount of information. We show that the full modeling, including the overall shape of the power spectrum, yields much better determinations of DA and H , hence the dark energy equation of state parameters such as w0 and wa, than the BAO-only analysis by more than a factor of two, provided that non-linear effects are under control. Subject headings: cosmology : theory — large-scale structure of universe