Breaking Cosmological Degeneracies in Galaxy Cluster Surveys with a Physical Model of Cluster Structure

Forthcoming large galaxy cluster surveys will yield tight constraints oncosmological models. It has been shown that in an idealized survey, containing> 10,000 clusters, statistical errors on dark energy and other cosmologicalparameters will be at the percent level. It has also been shown that through"self-calibration", parameters describing the mass-observable relation andcosmology can be simultaneously determined, though at a loss in accuracy byabout an order of magnitude. Here we examine the utility of an alternativeapproach of self-calibration, in which a parametrized ab-initio physical modelis used to compute cluster structure and the resulting mass-observablerelations. As an example, we use a modified-entropy ("pre-heating") model ofthe intracluster medium, with the history and magnitude of entropy injection asunknown input parameters. Using a Fisher matrix approach, we evaluate theexpected simultaneous statistical errors on cosmological and cluster modelparameters. We study two types of surveys, in which a comparable number ofclusters are identified either through their X-ray emission or through theirintegrated Sunyaev-Zel'dovich (SZ) effect. We find that compared to aphenomenological parametrization of the mass-observable relation, using ourphysical model yields significantly tighter constraints in both surveys, andoffers substantially improved synergy when the two surveys are combined. Theseresults suggest that parametrized physical models of cluster structure will beuseful when extracting cosmological constraints from SZ and X-ray clustersurveys. (abridged)Comment: 22 pages, 8 figures, accepted to Ap