PSR J0952-0607: Tightening a Record-High Neutron Star Mass

TL;DR

This paper presents a refined measurement of the neutron star in PSR J0952-0607, establishing it as one of the most massive known, thereby constraining the equation of state for dense matter.

Contribution

The study provides an improved mass measurement of the neutron star, tightening the upper mass limit and offering new constraints on the dense-matter equation of state.

Findings

Neutron star mass measured at 2.35±0.11 M_sun.

Maximum neutron star mass constrained to >2.27 M_sun at 1σ.

Supports the existence of very massive neutron stars, impacting dense matter models.

Abstract

We report on new orbit-minimum photometry and revised radial-velocity fitting that provide an improved measurement of the mass of the neutron star (NS) in pulsar PSR~J0952$-$0607 at $M_NS = 2.35\pm 0.11 M_\odot$. With its fast spin and unusually low magnetic field, this NS has evidently experienced unusual evolution, likely connected with its high mass, which is now $2.5\sigma$ above that of the heaviest pulsar with a white dwarf companion, as measured by Shapiro delay techniques. By tightening the mass measurement, we also raise the maximum (commonly called Tolman-Oppenheimer-Volkoff) NS mass to $M_{\rm TOV} > 2.27\,M_\odot$$(2.12\,M_\odot)$ at $1\sigma$$(3\sigma)$ confidence, which improves bounds on the dense-matter equation of state. While the statistical error decreases and systematic issues should be modest, uncertainties remain; we comment briefly on these factors and prospects for further improvement.