The hyperon superfluidity and the hyperon couplings in neutron stars within the relativistic mean field model

TL;DR

This paper investigates how hyperon couplings affect superfluidity in neutron star cores using the relativistic mean field model, revealing significant dependence on symmetry assumptions and potential constraints, with implications for astrophysics.

Contribution

It provides a systematic analysis of hyperon superfluidity variations under different coupling schemes and symmetry assumptions in neutron star matter.

Findings

Hyperon pairing strengths vary with coupling constraints and symmetry assumptions.

$eta$-equilibrium hyperon superfluidity is sensitive to hypernuclear potential uncertainties.

$ ext{Σ}^-$ hyperon pairing could serve as a cleaner probe for neutron star core physics.

Abstract

A systematic study of the effects of hyperon couplings on hyperon superfluidity is conducted by using the relativistic mean field model. Combining the slope of symmetry energy, the hyperon couplings are determined in two ways -- by the hypernuclear potentials or under the SU(3) symmetry. In either way, the hyperon coupling constants cannot be fixed uniquely but vary within a certain range due to the uncertainties in hypernuclear potentials or the breaking of SU(6) to SU(3) symmetry. When the coupling constants are constrained by the hypernuclear potentials, the pairings of $\Lambda$ and $\Xi^{0,-}$ are strong and they each show little variations. The pairing of $\Sigma^-$ is more sensitive to hyperon potentials and the slope of symmetry energy. Under the SU(3) symmetry, the superfluidity of various hyperons differ significantly. The dependence of the pairings of $\Lambda$ and $\Xi^{0,-}$ on the additional parameters of SU(3) symmetry are the opposite to that of the maximum mass of neutron stars on the additional parameters of SU(3) symmetry, while the pairing of $\Sigma^-$ shows a similar trend in general. These results suggest that the hyperon superfluidity associated with astrophysical processes is an essential window to probe the physics of neutron star cores, the hyperon-hyperon interactions and the SU(3) symmetry. Compared with other hyperons, $\Sigma^-$ could serve as a cleaner glass for this purpose.