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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 ~ 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.