Implications of Feebly Interacting Dark Sector on Neutron Star Properties and Constraints from GW170817

TL;DR

This study explores how feebly interacting dark matter influences neutron star properties, showing that dark matter can stiffen the equation of state and align theoretical predictions with gravitational wave observations from GW170817.

Contribution

It introduces a novel framework incorporating dark matter with light mediators into neutron star models, improving agreement with observational constraints.

Findings

Dark matter stiffens the neutron star equation of state.

Maximum neutron star mass aligns with observed massive pulsars.

Predicted radii and tidal deformabilities match GW170817 data.

Abstract

We investigate the effect of feeble interaction of dark matter (DM) with hadronic matter on the equation of state (EoS) and structural properties of neutron stars (NSs) in static conditions. For the purpose we adopt the effective chiral model for the hadronic sector and for the first time in the context of possible existence of DM inside NSs, we introduce DM-SM interaction through light new physics mediator. Moreover, the mass of DM fermion, the mediator and the coupling are adopted from the self-interaction constraint from Bullet cluster and from present day relic abundance. Within the considered framework, the work highlights the underlying stiffening of EoS in presence of DM fermion of mass of the order of a few GeV compared to the no-DM scenario. Consequently, the maximum gravitational mass of NS is obtained consistent with the bounds from the most massive pulsars which were not satisfied with the hadronic matter EoS alone. The estimates of radius and tidal deformability of 1.4 $M_{\odot}$ NS and the tidal deformabilities of the individual components of the binary neutron stars (BNS) associated with GW170817 are all in good agreement with the individual constraints obtained from GW170817 observation of BNS merger.