Constraints on Cosmological Parameters from Future Galaxy Cluster Surveys

Abstract

We study the expected redshift evolution of galaxy cluster abundance between 0 ≲ z ≲ 3 in different cosmologies, including the effects of the cosmic equation of state parameter w ≡ p/ρ. Using the halo mass function obtained in recent large-scale numerical simulations, we model the expected cluster yields in a 12 deg2 Sunyaev-Zeldovich effect (SZE) survey and a deep 104 deg2 X-ray survey over a wide range of cosmological parameters. We quantify the statistical differences among cosmologies using both the total number and redshift distribution of clusters. Provided that the local cluster abundance is known to a few percent accuracy, we find only mild degeneracies between w and either Ωm or h. As a result, both surveys will provide improved constraints on Ωm and w. The Ωm-w degeneracy from both surveys is complementary to those found either in studies of cosmic microwave background (CMB) anisotropies or of high-redshift supernovae (SNe). As a result, combining these surveys together with either CMB or SNe studies can reduce the statistical uncertainty on both w and Ωm to levels below what could be obtained by combining only the latter two data sets. Our results indicate a formal statistical uncertainty of ≈3% (68% confidence) on both Ωm and w when the SZE survey is combined with either the CMB or SN data; the large number of clusters in the X-ray survey further suppresses the degeneracy between w and both Ωm and h. Systematics and internal evolution of cluster structure at the present pose uncertainties above these levels. We briefly discuss and quantify the relevant systematic errors. By focusing on clusters with measured temperatures in the X-ray survey, we reduce our sensitivity to systematics such as nonstandard evolution of internal cluster structure.