Constraining dark energy via baryon acoustic oscillations in the (an)isotropic light-cone power spectrum

AIP - Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany e-mail: cwagner@aip.de

Received: 20 April 2007
Accepted: 15 May 2008

Abstract

Context. The measurement of the scale of the baryon acoustic oscillations (BAO) in the galaxy power spectrum as a function of redshift is a promising method to constrain the equation-of-state parameter of the dark energy w.

Aims. To measure the scale of the BAO precisely, a substantial volume of space must be surveyed. We test whether light-cone effects are important and whether the scaling relations used to compensate for an incorrect reference cosmology are in this case sufficiently accurate. We investigate the degeneracies in the cosmological parameters and the benefits of using the two-dimensional anisotropic power spectrum. Finally, we estimate the uncertainty with which w can be measured by proposed surveys at redshifts of about and , respectively.

Methods. Our data is generated by cosmological N-body simulations of the standard ΛCDM scenario. We construct galaxy catalogs by “observing” the redshifts of different numbers of mock galaxies on a light cone at redshifts of about and . From the “observed” redshifts, we calculate the distances, assuming a reference cosmology that depends on w_ref. We do this for , and -1.2 holding the other cosmological parameters fixed. By fitting the corresponding (an)isotropic power spectra, we determine the apparent scale of the BAO and the corresponding w.

Results. In the simulated survey we find that light-cone effects are small and that the simple scaling relations used to correct for the cosmological distortion work fairly well even for large survey volumes. The analysis of the two-dimensional anisotropic power spectra enables an independent determination to be made of the apparent scale of the BAO, perpendicular and parallel to the line of sight. This is essential for two-parameter w-models, such as the redshift-dependent dark energy model . Using Planck priors for the matter and baryon density and = 5% for the Hubble constant, we estimate that the BAO measurements of future surveys around and will be able to constrain, independently of other cosmological probes, a constant w to ~12% and ~11% (68% c.l.), respectively.