Dark Matter Induced Scalarization as a Possible Solution to the Hyperon Puzzle

TL;DR

This paper explores how a dark matter scalar field coupled to gravity can influence neutron star properties, potentially resolving the hyperon puzzle by allowing more massive stars despite hyperon effects.

Contribution

It introduces a novel scalar field coupling mechanism that enables neutron stars to reach higher masses even with hyperons present, expanding understanding of dark matter's role in stellar physics.

Findings

Neutron stars can exceed 2 solar masses with scalarization effects.

Multiple scalar-field solutions can coexist for certain coupling strengths.

Scalar self-interactions modify neutron star structure and maximum mass.

Abstract

We investigate the properties of neutron stars when a massive scalar field, which could comprise all dark matter, is non-minimally coupled to the Ricci scalar. This coupling generates additional contributions to the field's effective mass, leading to tachyonic instabilities inside neutron stars and giving rise to rich phenomenology. Within this framework, we obtain neutron-star configurations with maximum masses exceeding 2 $M_\odot$, even when hyperons, which typically soften the equation of state and significantly lower the maximum mass, are included. Furthermore, we find that larger coupling strengths lead to multiple solutions for the scalar-field configuration. We analyze the structure of the corresponding effective potential responsible for this behavior. We also investigate how the inclusion of a scalar self-interaction term, in addition to the non-minimal coupling, modifies the resulting neutron-star properties.