Constraining chameleon screening using galaxy cluster dynamics
Yacer Boumechta, Balakrishna S. Haridasu, Lorenzo Pizzuti, Minahil Adil Butt, C. Baccigalupi, Andrea Lapi
Abstract
We constrain the chameleon screening mechanism in galaxy clusters, essentially obtaining limits on the coupling strength $\ensuremath{\beta}$ and the asymptotic value of the field ${\ensuremath{\phi}}_{\ensuremath{\infty}}$. For this purpose, we utilized a collection of the nine relaxed galaxy clusters within the X-COP compilation in the redshift range of $z\ensuremath{\le}0.1$. We implement the formalism assuming a Navarro-Frenk-White mass profile for the dark matter density and study the degeneracy present between the mass ${M}_{500}$ and the chameleon coupling with a high degree of improvement in the constraints for excluded parameter space. We recast our constrain to an upper limit on the scalaron field in $f(R)$ subclass of models of $|{f}_{R0}|\ensuremath{\le}9.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$, using all the nine clusters and $|{f}_{R0}|\ensuremath{\le}1.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$ using only five clusters with Weak lensing priors taken into account, at a 95% confidence level. These bounds are consistent with existing limits in the literature and tighter than the constraints obtained with the same method by previous studies.