Power spectrum of the maxBCG sample: detection of acoustic oscillations using galaxy clusters

We use the direct Fourier method to calculate the redshift-space power spectrum of the maxBCG cluster catalogue – 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 non-linear effects, we show that currently favoured low matter density ‘concordance’Λ cold dark matter cosmology provides a very good fit to the estimated power. Thanks to the large volume (∼0.4 <it>h</it>−3 Gpc3), high clustering amplitude [linear effective bias parameter <it>b</it><inf>eff</inf>∼ 3 × (0.85/σ<inf>8</inf>)] and sufficiently high sampling density (∼3 × 10−5 <it>h</it>3 Mpc−3), the recovered power spectrum has a high enough signal-to-noise ratio to allow us to find weak evidence [∼2σ confidence level (CL)] for the baryonic acoustic oscillations (BAO). In case the clusters are additionally weighted by their richness, the resulting power spectrum has slightly higher large-scale amplitude and smaller damping on small scales. As a result, the CL for the BAO detection is somewhat increased: ∼2.5σ. The ability to detect BAO with a relatively small number of clusters is encouraging in the light of several proposed large cluster surveys.

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