Probing dark energy using baryonic oscillations in the galaxy power spectrum as a cosmological ruler

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 similar to 1 and similar to 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 similar to 1 can produce a measurement with accuracy Deltaw approximate to 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.