Using Multipoles of the Correlation Function to Measure H(z), D_A(z), and \beta(z) from Sloan Digital Sky Survey Luminous Red Galaxies

Galaxy clustering data can be used to measure the cosmic expansion history H(z), the angular-diameter distance D_A(z), and the linear redshift-space distortion parameter beta(z). Here we present a method for using effective multipoles of the galaxy two-point correlation function (\xi_0(s), \xi_2(s), \xi}_4(s), and \xi_6(s), with s denoting the comoving separation) to measure H(z), D_A(z)$, and beta(z), and validate it using LasDamas mock galaxy catalogs. Our definition of effective multipoles explicitly incorporates the discreteness of measurements, and treats the measured correlation function and its theoretical model on the same footing. We find that for the mock data, \xi_0+\xi_2+\xi_4 captures nearly all the information, and gives significantly stronger constraints on H(z), D_A(z), and beta(z), compared to using only \xi_0+\xi_2. We apply our method to the sample of luminous red galaxies (LRGs) from the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7) without assuming a dark energy model or a flat Universe. We find that \xi}_4(s) deviates on scales of s<60Mpc/h from the measurement from mock data (in contrast to \xi_0(s), \xi_2(s), and \xi_6(s)), thus we only use \xi_0+\xi_2 for our fiducial constraints. We obtain {H(0.35), D_A(0.35), Omega_mh^2, beta(z)} = {79.6_{-8.7}^{+8.3} km/s/Mpc, 1057_{-87}^{+88}Mpc, 0.103\pm0.015, 0.44\pm0.15} using \xi_0+\xi_2. We find that H(0.35)r_s(z_d)/c and D_A(0.35)/r_s(z_d) (where r_s(z_d) is the sound horizon at the drag epoch) are more tightly constrained: {H(0.35)r_s(z_d)/c, D_A(0.35)/r_s(z_d)} = {0.0437_{-0.0043}^{+0.0041}, 6.48_{-0.43}^{+0.44}\} using \xi_0+\xi_2.Comment: 12 pages, 11 figures. arXiv admin note: substantial text overlap with arXiv:1102.225

Modeling the Anisotropic Two-Point Galaxy Correlation Function on Small Scales and Improved Measurements of H(z), D_A(z), and f(z)sigma_8(z) from the Sloan Digital Sky Survey DR7 Luminous Red Galaxies

We present a simple and efficient phenomenological model for the two-dimensional two-point galaxy correlation function that works well over a wide range of scales, from large scales down to scales as small as 25Mpc/h. Our model incorporates nonlinear effects, a scale-dependent galaxy bias on small scales, and allows the redshift-space distortions to be scale and direction dependent. We validate our model using LasDamas mock catalogs, and apply it to the Sloan Digital Sky Survey (SDSS) DR7 Luminous Red Galaxies (LRGs). Using only the monopole and quadrupole of the correlation function measured from the SDSS DR7 LRGs, we obtain improved measurements H(z)r_s(z_d)/c=0.0433\pm 0.0042, D_A(z)/r_s(z_d)=6.59\pm 0.46, and f(z)sigma_8(z)=0.429\pm 0.089 at z=0.35, using the scale range of 25<s<120Mpc/h. We expect our results and model to be useful in tightening dark energy and gravity constraints from the full analysis of current and future galaxy clustering data.Comment: 9 pages, 5 figures, accepted by MNRAS, the last version matches accepted one. arXiv admin note: substantial text overlap with arXiv:1205.5573, arXiv:1102.225

Probing Dark Energy Using Galaxy Clustering Data

Dark energy is the most important unsolved mystery in cosmology today. Galaxy clustering provides one of the prime probes of dark energy. This work is focused on developing robust analysis techniques for interpreting galaxy clustering data. These are crucial for probing dark energy using galaxy clustering data.First, we present a method to measure the effective distance to z=0.35, DV(0.35) from the overall shape of the spherically-averaged two-point correlation function (2PCF) of the Sloan Digital Sky Survey Data Release 7 luminous red galaxy sample. We find DV(0.35) = 1428-73+74Mpc without assuming a dark energy model or a flat Universe. We find that the derived measurement of rs(zd)/DV(0.35) = 0.1143 &plusmn; 0.0030 (the ratio of the sound horizon at the drag epoch to the effective distance to z=0.35) has tighter constraint and is more robust with respect to possible systematic effects. It is also nearly uncorrelated to &Omega;m h^2 which might be sensitive to systematic effects.Then, we generalize the method to measure the Hubble parameter, H(z), and angular diameter distance, DA(z), from the two-dimensional 2PCF, and we find H(0.35) = 82.1-4.9+4.8km/s/Mpc, DA(0.35)=1048-58+60Mpc. We also find that the derived measurements of {H(0.35)rs(zd), rs(zd)/DA(0.35)} = {13020 &plusmn; 530 km/s, 0.1518 &plusmn; 0.0062} (with the correlation coefficient r = -0.0584) are nearly uncorrelated, have tighter constraints and are more robust with respect to possible systematic effects. Combining our results with the cosmic microwave background and supernova data, we obtain &Omega;k=-0.0004 &plusmn; 0.0070 and w=-0.996 &plusmn; 0.043 (assuming a constant dark energy equation of state).Our results represent the first measurements of H(z) and DA(z) 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

Completed SDSS-IV extended baryon oscillation spectroscopic survey: cosmological implications from two decades of spectroscopic surveys at the Apache Point Observatory

Artículo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, los autores pertenecientes a la UAM y el nombre del grupo de colaboración, si lo hubiereTítulo del la versión editorial: The Completed SDSS-IV extended Baryon Oscillation Spectroscopic Survey: Cosmological Implications from two Decades of Spectroscopic Surveys at the Apache Point observator