Global properties of rotating neutron stars with QCD equations of state

TL;DR

This study explores the global properties of rotating neutron stars using QCD-based equations of state, extending previous non-rotating models to include rotation effects and potential observational constraints.

Contribution

It extends the analysis of QCD equations of state to rotating neutron stars, providing new insights into their mass, radius, and moment of inertia constraints.

Findings

Mass-radius and mass-frequency relations for rotating neutron stars.

Allowed parameter regions constrained by QCD equations of state.

Potential observational constraints from pulsar measurements.

Abstract

We numerically investigate global properties of rotating neutron stars using the allowed band of QCD equations of state derived by Kurkela et al. This band is constrained by chiral effective theory at low densities and perturbative QCD at high densities, and is thus, in essence, a controlled constraint from first-principles physics. Previously, this band of equations of state was used to investigate non-rotating neutron stars only; in this work, we extend these results to any rotation frequency below the mass-shedding limit. We investigate mass--radius curves, allowed mass--frequency regions, radius--frequency curves for a typical 1.4-solar-mass star, and the values of the moment of inertia of the double pulsar PSR J0737-3039A, a pulsar whose moment of inertia may be constrained observationally in a few years. We present limits on observational data coming from these constraints, and identify values of observationally-relevant parameters that would further constrain the allowed region for the QCD equation of state. We also discuss how much this region would be constrained by a measurement of the moment of inertial of the double pulsar PSR J0737-3039A.