Constraining the scalar singlet and inert dark matter models using neutron stars

TL;DR

This study uses neutron stars to set new constraints on scalar singlet and inert dark matter models, revealing how neutron star observations can complement or surpass direct detection methods depending on dark matter properties.

Contribution

First constraints on scalar singlet and inert dark matter models derived from neutron star observations, exploring parameter space based on dark matter mass and interaction strength.

Findings

Neutron stars can provide stronger bounds than direct detection for heavy dark matter with negligible self-annihilation.

Constraints for light dark matter are comparable to Higgs decay limits unless particles are extremely light.

Results depend on dark matter self-interaction coupling and annihilation cross section.

Abstract

In the present work we study the scalar singlet as well as the Two-Higgs Doublet model inert dark matter particles impact on compact objects, and we provide the first constraints of the parameter space using neutron stars. The models discussed here are characterized by two free parameters, namely the mass $M_\chi$ of the scalar particle that plays the role of the dark matter in the Universe, and a dimensionless coupling constant $\lambda_\chi$ that determines the strength of the interaction of the dark matter particles with the Standard Model Higgs boson. By considering a typical neutron star we were able to obtain constraints on scalar dark matter depending on the DM annihilation cross section and self-interaction coupling constant. Our findings show that i) for heavy DM particles neutron stars can provide us with bounds better that the current limits from direct detection searches only when the self-annihilations of DM particles are negligible and the DM self-interaction coupling constant is very small, while ii) for light DM particles the bounds obtained here are comparable to limits from Higgs invisible decays unless the DM particles are extremely light.