Modified Gravity Makes Galaxies Brighter

TL;DR

This paper explores how modified gravity theories with screening mechanisms can increase star luminosity and galactic brightness, proposing observational tests to constrain these theories more tightly.

Contribution

It demonstrates that unscreened stars in dwarf galaxies can be significantly brighter, affecting galaxy luminosity and enabling new observational tests for modified gravity models.

Findings

Unscreened stars are more luminous and ephemeral.

Galactic luminosity can be substantially increased.

Potential to tighten constraints on modified gravity parameters.

Abstract

We investigate the effect of modifed gravity with screening mechanisms, such as the chameleon or symmetron models, upon the structure of main sequence stars. We find that unscreened stars can be significantly more luminous and ephemeral than their screened doppelgangers. By embedding these stars into dwarf galaxies, which can be unscreened for values of the parameters not yet ruled out observationally, we show that the cumulative effect of their increased luminosity can enhance the total galactic luminosity. We estimate this enhancement and find that it can be considerable given model parameters that are still under experimental scrutiny. By looking for systematic offsets between screened dwarf galaxies in clusters and unscreened galaxies in voids, these effects could form the basis of an independent observational test that can potentially lower the current experimental bounds on the model independent parameters of these theories by and order of magnitude or more.