Symmetry energy effects on the properties of hybrid stars

TL;DR

This paper explores how the symmetry energy influences the properties of hybrid stars with hadron-quark phase transitions, highlighting the impact of model parameters on star characteristics and observational constraints.

Contribution

It introduces a detailed investigation of symmetry energy effects in hybrid stars using a combined hadron-quark model with varied parameters, revealing their influence on star properties.

Findings

Symmetry energy behavior varies significantly with model parameters.

Star radii and tidal deformabilities mainly constrain symmetry energy density dependence.

Maximum star masses primarily constrain the EOS of nuclear and quark matter.

Abstract

Symmetry energy is an important part of the equation of state of isospin asymmetry matter. However, the huge uncertainties of symmetry energy remain at suprasaturation densities, where the phase transitions of strongly interacting matter and the quark matter symmetry energy are likely to be taken into account. In this work, we investigate the properties of symmetry energy by using a hybrid star with the hadron-quark phase transition. The interaction among strange quark matter (SQM) in hybrid stars is based on a 3-flavor NJL model with different vector and isovector channels, while the equation of state (EOS) of the nuclear matter is obtained by considering the ImMDI-ST interaction by varying the parameters x, y, and z. Our results indicate that the various parameters and coupling constants of the interactions from the ImMDI-ST and NJL model can lead to widely different trends for the symmetry energy in the hadron-quark mixed phase and the different onsets of the hadron-quark phase transition. In addition, it has been found that the radii and tidal deformabilities of hybrid stars constrain mostly the density dependence of symmetry energy while the observed maximum masses of hybrid stars constrain mostly the EOS of symmetric nuclear and quark matter.