2002/03/11 by Wayne Hu, Andrey V. Kravtsov · 2 citations
Physics and Astronomy · #astro-ph
paper · pdf · doi:10.1086/345846
published as Astrophys.J.584:702-715,2003 · 13 pages, 11 figures, submitted to ApJ
arxiv created 2002/03/11 · arxiv updated 2010/04/06
We present a general statistical framework for describing the effect of sample variance in the number counts of virialized objects and examine its effect on cosmological parameter estimation. Specifically, we consider effects of sample variance on the power spectrum normalization and properties of dark energy extracted from current and future local and high-redshift samples of clusters. We show that for future surveys that probe ever lower cluster masses and temperatures, sample variance is generally comparable to or greater than shot noise and thus cannot be neglected in deriving precision cosmological constraints. For example, sample variance is usually more important than shot variance in constraints on the equation of state of the dark energy from z < 1 clusters. Although we found that effects of sample variance on the sigma8-Omegam constraints from the current flux and temperature limited X-ray surveys are not significant, they may be important for future studies utilizing the shape of the temperature function to break the sigma8-Omegam degeneracy. We also present numerical tests clarifying the definition of cluster mass employed in cosmological modelling and accurate fitting formula for the conversion between different definitions of halo mass (e.g., virial vs. fixed overdensity).