The possibility of the secondary object in GW190814 as a neutron star

TL;DR

This study explores whether the secondary object in GW190814 could be a neutron star by calculating neutron star properties with advanced models, finding it remains a plausible scenario within current constraints.

Contribution

It systematically evaluates neutron star models using DDRMF parameterizations to assess the possibility of the secondary object being a neutron star.

Findings

Maximum neutron star mass ~2.55 M_7 with stiff equations of state

Neutron star radii and tidal deformabilities consistent with observations

Neutron star speed of sound remains below rac{rac{c}{rac{c}{rac{c}{rac{c}{rac{c}{ at the center

Abstract

A compact object was observed with a mass $2.50-2.67~M_\odot$ by LIGO Scientific and Virgo collaborations (LVC) in GW190814, which provides a great challenge to the investigations into the supranuclear matter. To study this object, properties of neutron star are systematically calculated within the latest density-dependent relativistic mean-field (DDRMF) parameterizations, which are determined by the ground state properties of spherical nuclei. The maximum masses of neutron star calculated by DD-MEX and DD-LZ1 sets can be around $2.55~M_\odot$ with quite stiff equations of state generated by their strong repulsive contributions from vector potentials at high densities. Their maximum speeds of sound $c_s/c$ are smaller than $\sqrt{0.8}$ at the center of neutron star and the dimensionless tidal deformabilities at $1.4~M_\odot$ are less than $800$. Furthermore, the radii of $1.4 ~M_\odot$ also satisfy the constraint from the observation of mass-radius simultaneous measurements (NICER). Therefore, we conclude that one cannot exclude the possibility of the secondary object in GW190814 as a neutron star composed of hadron matter from DDRMF models.