Testing generalized scalar-tensor theories of gravity with clusters of galaxies

We test the generalized scalar tensor theory in static systems, namely galaxy clusters. The degenerate higher-order scalar-tensor (DHOST) theory modifies the Newtonian potential through effective Newtonian constant and 81 parameter in the small scale, which modifies the hydrostatic equilibrium. We utilize the well-compiled X-COP catalog consisting of 12 clusters with intracluster medium (ICM) pressure profile by Sunyaev-Zel'dovich effect data and temperature profile by x-ray data for each cluster. We perform a fully Bayesian analysis modeling Navarro-Frenk-White (NFW) for the mass profile, and the simplified Vikhlinin model for the electron density. Carefully selecting suitable clusters to present our results, we find a mild to moderate, i.e., & SIM;2 & sigma; significance for a deviation from the standard scenario in four of the clusters. However, in terms of Bayesian evidence, we find either equivalent or mild preference for GR. We estimate a joint constraint of 81 = -0.030 & PLUSMN; 0.043 using eight clusters, for a modification from a ?CDM scenario. This limit is in very good agreement with theoretical ones and an order of magnitude more stringent than the previous constraint obtained using clusters. We also quote a more conservative limit of 81 = -0.061 & PLUSMN; 0.074. Finally, we comment on the tentative redshift dependence of the 81 parameter.