# Screened Fifth Forces Mediated by Dark Matter-Baryon Interactions: Theory and Astrophysical Probes

## TL;DR

This paper introduces a new screening mechanism where dark matter density influences baryonic interactions and Newton's constant, affecting astrophysical phenomena and cosmological observations.

## Contribution

It develops a novel dark matter density-dependent screening mechanism and explores its implications for astrophysics and cosmology.

## Key findings

- Dark matter density affects Newton's constant and gravitational parameters.
- Varying $G$ impacts stellar evolution and cosmological distance measures.
- Extragalactic tests of $\gamma$ can constrain the model.

## Abstract

We derive the details of a new screening mechanism where the interactions of baryons and dark matter can be screened according to the local dark matter density. In this mechanism, the value of Newton's constant is dark matter density-dependent, allowing for the possibility that astrophysical phenomena are very different in galaxies less dense than the Milky Way. The parameterized post Newtonian parameter $\gamma$, which quantifies the difference between kinematical and lensing probes, also depends on dark matter density. We calculate the effects of varying $G$ on various stages of stellar evolution, focusing on observables that impact cosmology: the Cepheid period--luminosity relation and the supernova Ia magnitude--redshift relation. Other potential tests of the model are also investigated including main-sequence, post-main sequence, and low mass dwarf stars. Finally, we discuss how extragalactic tests of $\gamma$ could provide complementary constraints.