Compact Star Properties from an Extended Linear Sigma Model

János Takátsy,Péter Kovács,Zsolt Szép,György Wolf

doi:10.3390/universe5070174

Abstract

The equation of state provided by effective models of strongly interacting matter should comply with the restrictions imposed by current astrophysical observations of compact stars. Using the equation of state given by the (axial-)vector meson extended linear sigma model, we determine the mass–radius relation and study whether these restrictions are satisfied under the assumption that most of the star is filled with quark matter. We also compare the mass–radius sequence with those given by the equations of state of somewhat simpler models.

Highlights

A lot of theoretical and experimental effort is devoted to study the strong interaction under extreme conditions
Since the Tolman–Oppenheimer–Volkoff (TOV) equations [11,12] provide a direct relation between the equation of state (EoS) of the compact star matter and the mass–radius (M–R) relation of the compact star, these data can help to select those effective models, used to describe the strongly interacting matter, whose predictions are consistent with compact star observables
Since our extended linear sigma model (eLSM) model was fitted to the hadron spectrum and not to the nuclear matter, we compare its results with those obtained in two relativistic models generally used in the description of compact stars, in order to assess the importance of various ingredients involved in these models

Summary

Introduction

A lot of theoretical and experimental effort is devoted to study the strong interaction under extreme conditions. The experiments ALICE [1] at CERN, and PHENIX [2] and STAR [3] at RHIC explored the strongly interacting matter at low density and high temperature. In this region the situation is satisfactory on the theoretical side; lattice calculations applicable at low density cannot yet be used at high densities [4]. Effective models are needed in the high density region where the existing experimental data (NA61 [5] at CERN, BES/STAR [3] at RHIC) are scarce and have rather bad statistics. Since the Tolman–Oppenheimer–Volkoff (TOV) equations [11,12] provide a direct relation between the equation of state (EoS) of the compact star matter and the mass–radius (M–R) relation of the compact star, these data can help to select those effective models, used to describe the strongly interacting matter, whose predictions are consistent with compact star observables

Methods

Results

Conclusion