The SDSS DR7 Galaxy Angular Power Spectrum: Volume-Limits and Galaxy Morphology

TL;DR

This paper measures the galaxy angular power spectrum from SDSS DR7 data, analyzing volume-limited and subsample variations to derive cosmological parameters, galaxy bias, and identify classification issues.

Contribution

It introduces a quadratic estimator with KL-compression for precise power spectrum measurement and explores galaxy type biases and evolution effects.

Findings

Cosmological parameters: mbda_m=0.267b1 0.038, mbda_b=0.045b1 0.012

Linear bias: b=1.075b1 0.056; early-type bias: 1.727b1 0.065; late-type bias: 1.256b1 0.051

Evidence of misclassification of late-type galaxies as stars in high stellar density regions.

Abstract

We use a quadratic estimator with KL-compression to calculate the angular power spectrum of a volume-limited Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7) galaxy sample out to l = 200. We also determine the angular power spectrum of selected subsamples with photometric redshifts z < 0.3 and 0.3 < z < 0.4 to examine the possible evolution of the angular power spectrum, as well as early-type and late-type galaxy subsamples to examine the relative linear bias. In addition, we calculate the angular power spectrum of the SDSS DR7 main galaxy sample in a ~ 53.7 square degree area out to l = 1600 to determine the SDSS DR7 angular power spectrum to high multipoles. We perform a \chi^2 fit to compare the resulting angular power spectra to theoretical nonlinear angular power spectra to extract cosmological parameters and the linear bias. We find the best-fit cosmological parameters of \Omega_m = 0.267 +- 0.038 and \Omega_b = 0.045 +- 0.012. We find an overall linear bias of b = 1.075 +- 0.056, an early-type bias of b_e = 1.727 +- 0.065, and a late-type bias of b_l = 1.256 +- 0.051. Finally, we present evidence of a selective misclassification of late-type galaxies as stars by the SDSS photometric data reduction pipeline in areas of high stellar density (e.g., at low Galactic latitudes).