Modified gravity in galaxy clusters: Joint analysis of Hydrostatics and Caustics

TL;DR

This paper combines hydrostatic and caustic methods to measure galaxy cluster masses, reducing biases and testing modified gravity models, thereby improving the accuracy of mass estimates and constraints on gravity theories.

Contribution

It introduces a joint analysis approach that incorporates hydrostatic assumptions into caustic measurements, effectively reducing mass bias and enabling better testing of modified gravity models in galaxy clusters.

Findings

No significant mass bias found between methods.

The approach tightens constraints on Chameleon and Vainshtein screening.

Method validates the consistency of mass measurements in galaxy clusters.

Abstract

We present a comprehensive joint analysis of two distinct methodologies for measuring the mass of galaxy clusters: hydrostatic measurements and caustic techniques. We show that by including cluster-specific assumptions obtained from hydrostatic measurements in the caustic method, the potential mass bias between these approaches can be significantly reduced. Applying this approach to two well-observed massive galaxy clusters A2029 and A2142. We find no discernible mass bias, affirming the method's validity. We then extend the analysis to modified gravity models and draw a similar conclusion when applying our approach. Specifically, our implementation allows us to investigate Chameleon and Vainshtein screening mechanisms, tightening the posteriors and enhancing our understanding of these modified gravity scenarios.