Neutron stars in degenerate higher-order scalar-tensor theories

TL;DR

This paper investigates neutron star structures within a class of degenerate higher-order scalar-tensor theories, revealing larger masses and radii compared to General Relativity, and analyzing rotational properties with minimal equation of state dependence.

Contribution

It introduces a detailed analysis of neutron stars in a specific DHOST theory, highlighting deviations from GR and their effects on star properties.

Findings

Neutron stars have larger masses and radii than in GR.

The moment of inertia-compactness relation is nearly equation-of-state independent.

Deviations from GR are characterized by a single parameter in the theory.

Abstract

We study neutron star configurations in a simple shift-symmetric subfamily of degenerate higher-order scalar-tensor (DHOST) theories, whose deviations from General Relativity (GR) are characterized by a single parameter. We compute the radial profiles of neutron stars in these theories of modified gravity, using several realistic equations of state for the neutron star matter. We find neutron stars with masses and radii significantly larger than their GR counterparts. We then consider slowly-rotating solutions and determine the relation between the dimensionless moment of inertia and the compactness, relation that has the property to be almost insensitive to the equation of state.