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 and supernovae. Using a nucleosynthesis prior on Ω_bh ², we measure the Hubble constant to be H₀ = 72.3±1.9 km s⁻¹Mpc⁻¹ from BAO+voids at z < 2, and H₀ = 69.0 ± 1.2 km s−1Mpc−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.