Constraining modified gravity from tidal phenomena in binary stars

TL;DR

This paper uses tidal phenomena in binary stars to place constraints on modified gravity theories, specifically beyond-Horndeski models, by analyzing how these theories affect stellar stability and disruption.

Contribution

It introduces a novel method to constrain beyond-Horndeski gravity theories using tidal effects in binary star systems, providing quantitative bounds on the parameter $psilon$.

Findings

Allowed range for $psilon$ is 0 to 0.47.

Constraints derived from modeling donor star masses and tidal disruption.

Method combines observational data with numerical modeling and Monte Carlo analysis.

Abstract

In beyond-Horndeski theories of gravity, the Vainshtein screening mechanism might only be partially effective inside stellar objects. This results in a modification of the pressure balance equation inside stars, often characterized by a single parameter ($\Upsilon$) in isotropic systems. We show how to constrain such theories of modified gravity, using tidal effects. We study such effects in cataclysmic variable star binaries and numerically obtain limits on the critical masses of the donor stars, below which they are tidally disrupted, by modeling them in beyond-Horndeski theories. This is contrasted with values of the donor masses, obtained using existing observational data, by a Monte Carlo error progression method. A best fit scenario of the two yields a parametric constraint in the theories that we consider, within the approximations used. Here, we obtain the allowed range $ 0 \le \Upsilon \le 0.47 $.