Imprints of Non-Symmetric Dark Matter Halos on Magnetars: A Two-Fluid Perspective

TL;DR

This paper explores how non-symmetric dark matter halos influence magnetar structure and observable signals, revealing potential gravitational wave signatures and period discrepancies caused by dark matter deformation effects.

Contribution

It introduces a two-fluid model considering gravitational interactions between dark matter and hadronic matter in magnetars, highlighting the impact of dark matter on star deformation and observable phenomena.

Findings

Dark matter halos increase with dark matter fraction and stiffness.

Magnetic deformation leads to non-symmetric dark matter halos.

Dark matter halos alter gravitational wave and period signatures.

Abstract

In this study, we investigate the impact of dark matter on the structure and deformation of magnetars. We assume a perturbative approach for the magnetic field deformation and that the dark matter only interacts gravitationally with hadronic matter. Assuming that dark matter is significantly softer than hadronic matter, we find that the magnetic field can affect dark matter through the deformation of space-time. The number of stars having a dark matter halo outside the visible surface of the star increases with an increase in dark matter fraction and the stiffness of the dark matter equation of state. As the magnetic field deforms the stars from sphericity, we can have a situation where we have a non-symmetric dark matter halo outside the star. The deformation of the dark matter halo gives rise to the discrepancies in the observed period $P$ (and period derivative $\dot{P}$) and gravitational wave signatures. The observed visible surfaces predict a lower period and gravitational wave strain than that with a dark matter halo. This can have interesting observational gravitational signatures unique to magnetars having a dark matter halo.