Constraining the Matter Power Spectrum Normalization using the SDSS/RASS and REFLEX Cluster surveys

Abstract

We describe a new approach to constrain the amplitude of the power spectrum of matter perturbations in the Universe, parametrized by sigma_8 as a function of the matter density Omega_0. We compare the galaxy cluster X-ray luminosity function of the REFLEX survey with the theoretical mass function of Jenkins et al. (2001), using the mass-luminosity relationship obtained from weak lensing data for a sample of galaxy clusters identified in Sloan Digital Sky Survey commissioning data and confirmed through cross-correlation with the ROSAT all-sky survey. We find sigma_8 = 0.38 Omega_0^(-0.48+0.27 Omega_ 0), which is significantly different from most previous results derived from comparable calculations that used the X-ray temperature function. We discuss possible sources of systematic error that may cause such a discrepancy, and in the process uncover a possible inconsistency between the REFLEX luminosity function and the relation between cluster X-ray luminosity and mass obtained by Reiprich & Bohringer (2001).