The Angular Power Spectra of Photometric SDSS LRGs

TL;DR

This paper presents new measurements of galaxy angular power spectra from the SDSS LRG survey, providing cosmological parameter constraints consistent with previous data and demonstrating robustness against systematics.

Contribution

The study introduces updated galaxy angular power spectra from MegaZ DR7 and compares photometric redshift estimation methods, serving as a methodological prototype for future surveys.

Findings

Constraints on  and m consistent with CMB data

Power spectra sensitive to redshift space distortions

Robustness against extinction and photometric redshift systematics

Abstract

We construct new galaxy angular power spectra based on the extended, updated and final SDSS II Luminous Red Galaxy (LRG) photometric redshift survey: MegaZ DR7. Encapsulating 7746 deg^{2} we utilise 723,556 photometrically determined LRGs between 0.45 < z < 0.65 in a 3.3 (Gpc h^{-1})^3 spherical harmonic analysis of the galaxy distribution. By combining four photometric redshift bins we find preliminary parameter constraints of f_{b} = \Omega_{b}/\Omega_{m} = 0.173 +/- 0.046 and \Omega_{m} = 0.260 +/- 0.035 assuming H_{0} = 75 km s^{-1} Mpc^{-1}, n_{s}=1 and \Omega_{k} = 0. These limits are consistent with the CMB and the previous data release (DR4). The C_{\ell} are sensitive to redshift space distortions and therefore we also recast our constraints into a measurement of \beta ~ \Omega_{m}^{0.55}/b in different redshift shells. The robustness of these power spectra with respect to a number of potential systematics such as extinction, photometric redshift and ANNz training set extrapolation are examined. The latter includes a cosmological comparison of available photometric redshift estimation codes where we find excellent agreement between template and empirical estimation methods. MegaZ DR7 represents a methodological prototype to next generation surveys such as the Dark Energy Survey (DES) and, furthermore, is a photometric precursor to the spectroscopic BOSS survey. Our galaxy catalogue and all power spectra data can be found at http://zuserver2.star.ucl.ac.uk/~sat/MegaZ/MegaZDR7.tar.gz.