Constraining hyperonic relativistic mean-field models with rapidly rotating neutron stars

Abstract

Motivated by the recent mass measurement of the black-widow pulsar PSR~J0952$-$0607 with $M=2.35\pm0.11\,M_\odot$, we investigate how the masses of heavy, rapidly rotating millisecond pulsars can be used to constrain relativistic mean-field (RMF) models containing hyperonic degrees of freedom. In our approach, hyperons are incorporated following the spin-flavor SU(6) symmetry scheme for the vector-meson couplings. We find that increasing the nonlinear $ω$-meson vector self-coupling parameter $ζ$ suppresses the hyperon fraction and can alter the onset ordering of the $Σ^-$ and $Ξ^-$ hyperons. By computing rotating neutron-star configurations at the observed spin frequency $707\,\mathrm{Hz}$ of PSR~J0952$-$0607, we identify RMF models compatible with this pulsar's observed lower-mass bound. Using an empirical relation for the maximum neutron star mass, the PSR~J0952$-$0607 observational contraint is mapped onto the allowed RMF parameter space in $n_0$, $m^\ast$, and $ζ$.