Probing Dark Energy Using Baryonic Oscillations in the Galaxy Power Spectrum as a Cosmological Ruler

Abstract

We show that the baryonic oscillations expected in the galaxy power spectrum may be used as a 'standard cosmological ruler' to facilitate accurate measurement of the cosmological equation of state. Our approach involves a straightforward measurement of the oscillation 'wavelength' in Fourier space, which is fixed by fundamental linear physics in the early universe and hence is highly model-independent. We quantify the ability of future large-scale galaxy redshift surveys with mean redshifts z ∼ 1 and ∼3 to delineate the baryonic peaks in the power spectrum, and we derive corresponding constraints on the parameter w describing the equation of state of the dark energy. For example, a survey of 4 times the Sloan volume at z ∼ 1 can produce a measurement with accuracy Δw ≈ 0.1. We suggest that this method of measuring the dark energy powerfully complements other probes, such as Type Ia supernovae, and suffers from a different (and arguably less serious) set of systematic uncertainties.