Stellar properties indicating the presence of hyperons in neutron stars

TL;DR

This paper identifies specific stellar features, such as the curvature of mass-radius relations and tidal deformability derivatives, that indicate the presence of hyperons in neutron stars, providing observational signatures to distinguish hyperonic from nucleonic matter.

Contribution

It introduces measurable stellar features, like the curvature of R(M) and the second derivative of bb(M), as indicators of hyperons in neutron stars, advancing observational methods.

Findings

Negative curvature of R(M) indicates hyperons.

Reduced second derivative of bb(M) suggests hyperonic matter.

Slope differences in R(M) and bb(M) distinguish hyperonic from nucleonic models.

Abstract

We describe distinctive stellar features indicating the presence of hyperons in neutron stars as compared to purely nucleonic systems. A strongly negative curvature of the mass-radius relation $R(M)$ is characteristic of hyperons, which can be determined from measurements of neutron stars with three different masses. Similarly, a reduced second derivative of the tidal deformability as function of mass \lambda(M) points to hyperonic degrees of freedom in NS matter. The slopes of such curves R(M) and \lambda(M) can distinguish a hyperonic equation of state from purely nucleonic models if they appear increased (decreased for \lambda(M)) relative to the maximum mass of neutron stars.