Neutron star properties with careful parameterization in the (axial)vector meson extended linear sigma model

TL;DR

This study models quark matter in neutron star cores using an extended linear sigma model, revealing parameter constraints necessary for consistency with astrophysical observations and providing insights into hybrid star properties.

Contribution

It introduces a parameter constraint in the quark-meson model to ensure chiral restoration and explores how model parameters affect neutron star properties and observational constraints.

Findings

Low sigma meson masses are needed for radius constraints.

Maximum hybrid star mass is only slightly affected by phase transition parameters.

A quark-vector meson coupling constraint of 2.6 < g_V < 4.3 is established.

Abstract

The existence of quark matter inside the cores of heavy neutron stars is a possibility which can be probed with modern astrophysical observations. We use an (axial)vector meson extended quark-meson model to describe quark matter in the core of neutron stars. We discover that an additional parameter constraint is necessary in the quark model to ensure chiral restoration at high densities. By investigating hybrid star sequences with various parameter sets we show that low sigma meson masses are needed to fulfill the upper radius constraints, and that the maximum mass of stable hybrid stars is only slightly dependent on the parameters of the crossover-type phase transition. Using this observation and results from recent astrophysical measurements a constraint of 2.6 < g_V < 4.3 is set for the constituent quark - vector meson coupling. The effect of a nonzero bag constant is also investigated and we observe that its effect is small for values adopted in previous works.