The Possibility of the Secondary Object in GW190814 as a Neutron Star

A compact object was observed with a mass of $2.50\text{--}2.67M_{\odot }$ by LIGO Scientific and Virgo collaborations (LVC) in GW190814, which provides a great challenge to investigations of supranuclear matter. To study this object, the properties of the 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 the neutron star calculated by DD-MEX and DD-LZ1 sets can be around $2.55M_{\odot }$ 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 the neutron star, and the dimensionless tidal deformabilities at $1.4M_{\odot }$ are less than 800. Furthermore, the radii of $1.4M_{\odot }$ also satisfy the constraint from the observation of simultaneous mass–radius measurements (Neutron star Interior Composition Explorer). 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.