Modeling the cross power spectrum of the Sunyaev-Zel’dovich and X-ray surveys

Institut d’Astrophysique Spatiale, CNRS (UMR 8617) and Université Paris-Sud 11, Bâtiment 121, 91405 Orsay, France
e-mail: ghurier@ias.u-psud.fr

Received: 5 March 2014
Accepted: 25 May 2014

Abstract

The thermal Sunyaev-Zel’dovich (tSZ) effect and X-ray emission from galaxy clusters have been used extensively to constrain cosmological parameters. These constraints are highly sensitive to the relations between cluster masses and observables (tSZ and X-ray fluxes). The cross-correlation of tSZ and X-ray data is thus a powerful tool, in addition of tSZ and X-ray based analysis, for testing our modeling of both tSZ and X-ray emission from galaxy clusters. We chose to explore this cross-correlation because both emissions trace the hot gas in galaxy clusters and thus constitute one of the easiest correlations that can be studied. We present a complete modeling of the cross-correlation between tSZ effect and X-ray emission from galaxy clusters and focus on the dependencies with cluster scaling laws and cosmological parameters. We show that current knowledge of cosmological parameters and scaling-law parameters leads to uncertainties of 48% on the overall normalization of the tSZ-X cross-correlation power spectrum. We present the expected signal-to-noise ratio for the tSZ-X cross-correlation angular power spectrum and consider the sensitivity of actual tSZ and X-ray surveys from Planck-like data and ROSAT. We demonstrate that this signal-to-noise can reach 31.5 in a realistic situation, leading to a constraint on the amplitude of tSZ-X cross-correlation up to 3.2%, which is ten times better than actual modeling limitations. Consequently, using it in addition to other probes of cosmological parameters and scaling relations, we show that the tSZ-X is a powerful probe that constrains the cosmological parameters of scaling relations.