Feeble DM-SM Interaction via New Scalar and Vector Mediators in Rotating Neutron Stars

TL;DR

This study explores how introducing new scalar and vector mediators affects dark matter interactions within rotating neutron stars, finding minimal impact on their structure but potential explanations for observed massive pulsars and gravitational wave events.

Contribution

It extends previous models by including a vector mediator, analyzing its effects on neutron star properties and rotational dynamics, and comparing results with recent astrophysical observations.

Findings

Vector mediator does not significantly alter the EoS or static NS properties.

DM admixed NSs can explain massive pulsars and gravitational wave data.

Rotational properties suggest GW190814's secondary could be a DM admixed NS.

Abstract

We investigate the possible presence of dark matter (DM) in massive and rotating neutron stars (NSs). For the purpose we extend our previous work [1] to introduce a light new physics vector mediator besides a scalar one in order to ensure feeble interaction between fermionic DM and $\beta$ stable hadronic matter in NSs. The masses of DM fermion, the mediators and the couplings are chosen consistent with the self-interaction constraint from Bullet cluster and from present day relic abundance. Assuming that both the scalar and vector mediators contribute equally to the relic abundance, we compute the equation of state (EoS) of the DM admixed NSs to find that the present consideration of the vector new physics mediator do not bring any significant change to the EoS and static NS properties of DM admixed NSs compared to the case where only the scalar mediator was considered [1]. However, the obtained structural properties in static conditions are in good agreement with the various constraints on them from massive pulsars like PSR J0348+0432 and PSR J0740+6620, the gravitational wave (GW170817) data and the recently obtained results of NICER experiments for PSR J0030+0451 and PSR J0740+6620. We also extended our work to compute the rotational properties of DM admixed NSs rotating at different angular velocities. The present results in this regard suggest that the secondary component of GW190814 may be a rapidly rotating massive DM admixed NS. The constraints on rotational frequency from pulsars like PSR B1937+21 and PSR J1748-2446ad are also satisfied by our present results. Also, the constraints on moment of inertia are satisfied considering slow rotation. The universality relation in terms of normalized moment of inertia also holds good with our DM admixed EoS.