Neutron stars in the symmetron model

TL;DR

This paper investigates how neutron stars can reveal effects of symmetron dark energy models, which are usually hidden by screening mechanisms, by analyzing their equilibrium and stability properties.

Contribution

It explores the behavior of neutron stars in symmetron models, showing potential partial failure of screening and sensitivity to model corrections.

Findings

Symmetron field amplified inside neutron stars by several orders of magnitude.

Unscreened neutron stars exhibit properties sensitive to linear coupling corrections.

Neutron star observations can probe symmetron dark energy models.

Abstract

Screening mechanisms are often deployed by dark energy models in order to conceal the effects of their new degrees of freedom from the scrutiny of terrestrial and solar system experiments. However, extreme properties of nuclear matter may lead to a partial failure of screening mechanisms inside the most massive neutron stars observed in Nature, opening up the possibility of probing these theories with neutron star observations. In this work we explore equilibrium and stability properties of neutron stars in two variants of the symmetron model. We show that around sufficiently compact neutron stars, the symmetron is amplified with respect to its background, cosmological value by several orders of magnitude, and that properties of such unscreened stars are sensitive to corrections to the leading linear coupling between the symmetron and matter.