GW190814's secondary component with mass $(2.50-2.67)$ M${}_{\odot }$ as a super-fast pulsar

Abstract

Using Stergioulas's RNS code for investigating fast pulsars with Equation of States (EOSs) on the causality surface (where the speed of sound equals that of light) of the high-density EOS parameter space satisfying all known constraints from both nuclear physics and astrophysics, we show that one possible explanation for the GW190814's secondary component of mass $(2.50-2.67)$ M${}_{\odot }$ is that it is a super-fast pulsar spinning faster than 971 Hz about 42\% below its Kepler frequency. If confirmed, it would be the fastest pulsar with the highest mass observed presently. There is a large and physically allowed EOS parameter space below the causality surface where pulsars heavier than 2.50 M${}_{\odot }$ are supported if they can rotate even faster with critical frequencies depending strongly on the high-density behavior of nuclear symmetry energy.

Comments: New results and discussions added to strengthen our original conclusions. The Astrophysical Journal in press