Power spectrum of the maxBCG cluster sample: new evidence for the acoustic features

TL;DR

This study measures the power spectrum of a large galaxy cluster sample, finding weak evidence for acoustic features consistent with LambdaCDM cosmology, despite challenges from photometric redshift errors.

Contribution

It provides the first detailed power spectrum analysis of the maxBCG cluster catalog, incorporating redshift errors and nonlinear effects, and offers new evidence for acoustic features in galaxy clusters.

Findings

Weak (~2σ) evidence for acoustic features in the power spectrum.

Good fit of LambdaCDM model to the observed power spectrum.

Large volume and high sampling density enable high signal-to-noise measurements.

Abstract

We use the direct Fourier method to calculate the redshift-space power spectrum of the maxBCG cluster catalog (Koester et al. 2007) -- currently by far the largest existing galaxy cluster sample. The total number of clusters used in our analysis is 12,616. After accounting for the radial smearing effect caused by photometric redshift errors and also introducing a simple treatment for the nonlinear effects, we show that currently favored low matter density ``concordance'' LambdaCDM cosmology provides a very good fit to the estimated power. Thanks to the large volume (~ 0.4 h^{-3} Gpc^3), high clustering amplitude (linear effective bias parameter b_{eff} ~ 3x(0.85/sigma_8)), and sufficiently high sampling density (~ 3x10^{-5} h^{3} Mpc^{-3}) the recovered power spectrum has high enough signal to noise to allow us to find weak evidence (~ 2sigma CL) for the acoustic features. These results are encouraging in light of the several proposed large cluster surveys. In case we use the photometric redshift errors as suggested in Koester et al. (2007) we are left with the excess large-scale power which has previously been noticed by several other authors.