Testing Low-Redshift Cosmic Acceleration with Large-Scale Structure

We examine the cosmological implications of measurements of the void-galaxy cross-correlation at redshift z=0.57 combined with baryon acoustic oscillation (BAO) data at 0.1<z<2.4. We find direct evidence of the late-time acceleration due to dark energy at >10σ significance from these data alone, independent of the cosmic microwave background (CMB) and supernovae. Using a nucleosynthesis prior on Ωbh², we measure the Hubble constant to be H₀=72.3±1.9 km s⁻¹ Mpc⁻¹ from BAO+voids at z<2, and H₀=69.0±1.2 km s⁻¹ Mpc⁻¹ when adding Lyman-α BAO at z=2.34, both independent of the CMB. Adding voids to CMB, BAO, and supernova data greatly improves measurement of the dark energy equation of state, increasing the figure of merit by >40%, but remaining consistent with flat Λ cold dark matter.