Cosmological Constraints from SDSS maxBCG Cluster Abundances

Eduardo Rozo; Risa H. Wechsler; Benjamin P. Koester; Timothy A. McKay; August E. Evrard; David Johnston; Erin S. Sheldon; James Annis; Joshua A. Frieman

arXiv · astro-ph/0703571

Cosmological Constraints from SDSS maxBCG Cluster Abundances

Eduardo Rozo·Risa H. Wechsler·Benjamin P. Koester·Timothy A. McKay·August E. Evrard·David Johnston·Erin S. Sheldon·James Annis·Joshua A. Frieman

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Abstract

We perform a maximum likelihood analysis of the cluster abundance measured in the SDSS using the maxBCG cluster finding algorithm. Our analysis is aimed at constraining the power spectrum normalization $σ_8$, and assumes flat cosmologies with a scale invariant spectrum, massless neutrinos, and CMB and supernova priors Omega_m*h^2=0.128+/-0.01 and h=0.72+/-0.05 respectively. Following the method described in the companion paper Rozo et al. 2007, we derive σ_8=0.92+/-0.10$ (1-sigma) after marginalizing over all major systematic uncertainties. We place strong lower limits on the normalization, sigma_8>0.76 (95% CL) (>0.68 at 99% CL). We also find that our analysis favors relatively low values for the slope of the Halo Occupation Distribution (HOD), alpha=0.83+/-0.06. The uncertainties of these determinations will substantially improve upon completion of an ongoing campaign to estimate dynamical, weak lensing, and X-ray cluster masses in the SDSS maxBCG cluster sample.

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Eduardo Rozo, Risa H. Wechsler, Benjamin P. Koester, Timothy A. McKay, August E. Evrard, David Johnston, Erin S. Sheldon, James Annis, Joshua A. Frieman. 2007-03-21. Cosmological Constraints from SDSS maxBCG Cluster Abundances. https://arxiv.org/abs/astro-ph/0703571

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