Can Old Galaxies at High Redshifts and Baryon Acoustic Oscillations Constrain H 0 ?

A new age--redshift test is proposed in order to constrain H 0 on the basis of the existence of old high-redshift galaxies (OHRGs). In the flat Λ cold dark matter model, the value of H 0 is heavily dependent on the mass density parameter Ω M = 1 − Ω Λ . Such a degeneracy can be broken through a joint analysis involving the OHRG and baryon acoustic oscillation signature. By assuming a galaxy incubation time, t inc = 0.8 ± 0.4 Gyr, our joint analysis yields a value of H 0 = 71 ± 4 km s −1 Mpc −1 (1σ) with the best-fit density parameter Ω M = 0.27 ± 0.03. Such results are in good agreement with independent studies from the Hubble Space Telescope key project and recent estimates of the Wilkinson Microwave Anisotropy Probe , thereby suggesting that the combination of these two independent phenomena provides an interesting method to constrain the Hubble constant.