The Sloan Digital Sky Survey Data Release 7 galaxy angular power spectrum

Abstract

We calculate the angular power spectrum of galaxies selected from the Sloan Digital Sky Survey (SDSS) Data Release 7 by using a quadratic estimation method with Karhunen–Loeve compression. The primary data sample includes over 18 million galaxies covering more than 5700 deg2 after masking areas with bright objects, reddening greater than 0.2 mag and seeing of more than 1.5 arcsec. We test for systematic effects by calculating the angular power spectrum by SDSS stripe and find that these measurements are minimally affected by seeing and reddening. We calculate the angular power spectrum for l≤ 200 multipoles by using 40 bandpowers for the full sample, and l≤ 1000 multipoles using 50 bandpowers for individual stripes. We also calculate the angular power spectrum for this sample separated into 3 mag bins with mean redshifts of z= 0.171, 0.217 and 0.261 to examine the evolution of the angular power spectrum. We determine the theoretical linear angular power spectrum by projecting the 3D power spectrum to two dimensions for a basic comparison to our observational results. By minimizing the χ2 fit between these data and the theoretical linear angular power spectrum we measure a loosely constrained fit of with a linear bias of b= 0.94 ± 0.04.