Measuring the Cosmic Evolution of Dark Energy with Baryonic Oscillations in the Galaxy Power Spectrum

Abstract

We use Monte Carlo techniques to simulate the ability of future large high-redshift galaxy surveys to measure the temporal evolution of the dark energy equation of state w(z), using the baryonic acoustic oscillations in the clustering power spectrum as a ``standard ruler.'' Our analysis utilizes only the oscillatory component of the power spectrum and not its overall shape, which is potentially susceptible to broadband tilts induced by a host of model-dependent systematic effects. Our results are therefore robust and conservative. We show that baryon oscillation constraints can be thought of, to high accuracy, as a direct probe of the distance-redshift and expansion rate-redshift relations where distances are measured in units of the sound horizon. Distance precisions of 1% are obtainable for a fiducial redshift survey covering 10,000 deg² and redshift range 0.5<z<3.5. If the dark energy is further characterized by w(z)=w₀+w₁z (with a cutoff in the evolving term at z=2), we can then measure the parameters w₀ and w₁ with a precision exceeding current knowledge by a factor of 10:1 σ accuracies Δw₀~0.03 and Δw₁~0.06 are obtainable (assuming a flat universe and that the other cosmological parameters Ω_m and h could be measured independently to a precision of +/-0.01 by combinations of future CMB and other experiments). We quantify how this performance degrades with redshift/areal coverage and knowledge of Ω_m and h and discuss realistic observational prospects for such large-scale spectroscopic redshift surveys, with a variety of diverse techniques. We also quantify how large photometric redshift imaging surveys could be utilized to produce measurements of (w₀,w₁) with the baryonic oscillation method, which may be competitive in the short term.