Investigate viable modified gravity models

Background: Accurate measurement of the gravitational redshift in galaxy clusters is a promising method for constraining modifications to general relativity (GR). The observable signal depends on the cluster’s gravitational potential.

Question / Future Work: Future work should investigate how more modified gravity models, which survive the strong constraints from GW170817 observations, alter the gravitational potentials of galaxy clusters and thus affect the gravitational redshift signal.

Why It Matters: The current analysis focuses on parameterizations compatible with standard modified gravity models; exploring new, viable models is necessary for a comprehensive test of modified gravity.

Evidence: Future work should be devoted to investigating how more modified gravity models surviving the GW170817 detection alter the gravitational potentials of clusters (Ezquiaga and Zumalacárregui, 2017).