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 $\Xi_1$ parameter
in the small scale, which modifies the hydrostatic equilibrium. We utilize the
well-compiled X-COP catalog consisting of 12 clusters with Intra Cluster Medium
(ICM) pressure profile by Sunyaev-Zeldovich 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 4 of the clusters.
However, in terms of Bayesian evidence, we find either equivalent or mild
preference for GR. We estimate a joint constraint of $\Xi_1 = -0.030 \pm 0.043$
using 8 clusters, for a modification from a $\Lambda$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 $\Xi_1 = -0.061 \pm 0.074$. Finally, we comment on
the tentative redshift dependence ($\Xi_1(z)$), finding a mild preference ($
\lesssim 2\sigma$) for the same.
