Probing modified gravity via the mass-temperature relation of galaxy clusters

TL;DR

This paper explores how the mass-temperature relation of galaxy clusters can test modified gravity theories, revealing significant deviations from standard gravity predictions especially in less massive clusters, using cosmological simulations.

Contribution

It demonstrates that the mass-temperature relation can distinguish certain modified gravity models from Einstein's gravity, especially in less massive galaxy clusters, through cosmological simulations.

Findings

Modified gravity models alter the mass-temperature relation significantly.

Screened modified gravities show deviations mainly in less massive clusters.

Gas mass-temperature relation exhibits even larger deviations than thermal mass-temperature.

Abstract

We propose that the mass-temperature relation of galaxy clusters is a prime candidate for testing gravity theories beyond Einstein's general relativity, for modified gravity models with universal coupling between matter and the scalar field. For non-universally coupled models we discover that the impact of modified gravity can remain hidden from the mass-temperature relation. Using cosmological simulations, we find that in modified gravity the mass-temperature relation varies significantly from the standard gravity prediction of $M \propto T^{1.73}$. To be specific, for symmetron models with a coupling factor of $\beta=1$ we find a lower limit to the power law as $M\propto T^{1.6}$; and for f(R) gravity we compute predictions based on the model parameters. We show that the mass-temperature relation, for screened modified gravities, is significantly different from that of standard gravity for the less massive and colder galaxy clusters, while being indistinguishable from Einstein's gravity at massive, hot galaxy clusters. We further investigate the mass-temperature relation for other mass estimates than the thermal mass estimate, and discover that the gas mass-temperature results show an even more significant deviations from Einstein's gravity than the thermal mass-temperature.