Secondary component of gravitational-wave signal GW190814 as an anisotropic neutron star

TL;DR

This paper explores the possibility that the secondary object in GW190814 is an anisotropic neutron star, modeling its properties and constraining its parameters using gravitational-wave data and theoretical models.

Contribution

It introduces a model of an anisotropic neutron star using the Krori-Barua ansatz and constrains its parameters based on LIGO/Virgo observations, suggesting the object could be an anisotropic neutron star.

Findings

The secondary component could be an anisotropic neutron star with radius 13.2-14.0 km.

The boundary density of the anisotropic core is constrained to (3.5-4.0)×10^14 g/cm^3.

The model is compatible with LIGO/Virgo gravitational-wave constraints.

Abstract

The gravitational-wave signal GW190814 involves a compact object with mass $(2.50-2.67){\rm M}_\odot$ within the so-called low mass gap. As yet, a general consensus on its nature, being a black hole, a neutron star or an exotic star, has not been achieved. We investigate the possibility this compact object to be an anisotropic neutron star. Anisotropies in a neutron star core arise naturally by effects such as superfluidity, hyperons, strong magnetic fields and allow the maximum mass to exceed that of the ideally isotropic stars. We consider the Krori-Barua ansatz to model an anisotropic core and constrain the equation of state with LIGO/Virgo observations GW170817 and GW190814. We find that the GW190814 secondary component can be an anisotropic neutron star compatible with LIGO/Virgo constraints if the radius attains a value in the range $(13.2-14.0)\,{\rm km}$ with the anisotropic core's boundary density in the range $(3.5-4.0)\cdot 10^{14}{\rm g}/{\rm cm}^3$.