Acoustic scale from the angular power spectra of SDSS-III DR8 photometric luminous galaxies

TL;DR

This paper measures the acoustic scale from SDSS-III DR8 galaxy data to estimate the angular diameter distance at redshift 0.54, providing constraints on cosmology with improved precision and comparison to LCDM expectations.

Contribution

It presents a novel measurement of the BAO angular scale using photometric galaxy data and a robust method to marginalize over non-BAO signals, enhancing cosmological distance estimates.

Findings

Measured D_A at z=0.54 as 1411±65 Mpc

Derived D_A/r_s=9.212+0.416-0.404, consistent with previous BAO results

Found D_A slightly higher than LCDM predictions by 1.4 sigma

Abstract

We measure the acoustic scale from the angular power spectra of the Sloan Digital Sky Survey III (SDSS-III) Data Release 8 imaging catalog that includes 872,921 galaxies over ~ 10,000 deg^2 between 0.45<z<0.65. The extensive spectroscopic training set of the Baryon Oscillation Spectroscopic Survey (BOSS) luminous galaxies allows precise estimates of the true redshift distributions of galaxies in our imaging catalog. Utilizing the redshift distribution information, we build templates and fit to the power spectra of the data, which are measured in our companion paper, Ho et al. 2011, to derive the location of Baryon acoustic oscillations (BAO) while marginalizing over many free parameters to exclude nearly all of the non-BAO signal. We derive the ratio of the angular diameter distance to the sound horizon scale D_A/r_s= 9.212 + 0.416 -0.404 at z=0.54, and therefore, D_A= 1411+- 65 Mpc at z=0.54; the result is fairly independent of assumptions on the underlying cosmology. Our measurement of angular diameter distance D_A is 1.4 \sigma higher than what is expected for the concordance LCDM (Komatsu et al. 2011), in accordance to the trend of other spectroscopic BAO measurements for z >~ 0.35. We report constraints on cosmological parameters from our measurement in combination with the WMAP7 data and the previous spectroscopic BAO measurements of SDSS (Percival et al. 2010) and WiggleZ (Blake et al. 2011). We refer to our companion papers (Ho et al. 2011; de Putter et al. 2011) for investigations on information of the full power spectrum.