Hyperons and massive neutron stars: the role of hyperon potentials

TL;DR

This paper explores how hyperon potentials and other nuclear parameters influence the equation of state of dense matter, affecting the maximum mass of neutron stars, with implications for understanding observed massive pulsars.

Contribution

It demonstrates that hyperon potentials have limited impact on neutron star mass limits, which are primarily affected by an additional vector meson and nucleon effective mass.

Findings

Hyperon potentials minimally affect maximum neutron star mass.

An additional vector meson is necessary to reach observed mass limits.

Maximum mass is sensitive to the nucleon effective mass, not the compression modulus.

Abstract

The constituents of cold dense matter are still far from being understood. However, neutron star observations such as the recently observed pulsar PSR J1614-2230 with a mass of 1.97+/-0.04 M_solar help to considerably constrain the hadronic equation of state (EoS). We systematically investigate the influence of the hyperon potentials on the stiffness of the EoS. We find that they have but little influence on the maximum mass compared to the inclusion of an additional vector meson mediating repulsive interaction amongst hyperons. The new mass limit can only be reached with this additional meson regardless of the hyperon potentials. Further, we investigate the impact of the nuclear compression modulus and the effective mass of the nucleon at saturation density on the high density regime of the EoS. We show that the maximum mass of purely nucleonic stars is very sensitive to the effective nucleon mass but only very little to the compression modulus.