Measurements of H(z) and DA(z) from the two-dimensional two-point correlation function of Sloan Digital Sky Survey luminous red galaxies




We present a method for measuring the Hubble parameter, H(z), and angular diameter distance, DA(z), from the two-dimensional two-point correlation function and validate it using LasDamas mock galaxy catalogues. Applying our method to the sample of luminous red galaxies from the Sloan Digital Sky Survey Data Release 7, we measure math formula and math formula Mpc without assuming a dark energy model or a flat universe. We find that the derived measurements of H(0.35) rs(zd)/c and DA(0.35)/rs(zd) [where rs(zd) is the sound horizon at the drag epoch] are nearly uncorrelated, have tighter constraints and are more robust with respect to possible systematic effects. Our galaxy clustering measurements of math formula (with the correlation coefficient r = 0.0604) can be used to combine with cosmic microwave background and any other cosmological data sets to constrain dark energy. Our results represent the first measurements of H(z) and DA(z) (or H(z) rs(zd)/c and DA(0.35)/rs(zd)) from galaxy clustering data. Our work has significant implications for future surveys in establishing the feasibility of measuring both H(z) and DA(z) from galaxy clustering data.