Constraining the parameterized neutron star equation of state with astronomical observations

TL;DR

This paper uses phenomenological models of neutron star equations of state to analyze their consistency with astronomical data, highlighting limitations in explaining pulsar glitches and braking indices, and proposing future observational constraints.

Contribution

It introduces a comprehensive analysis of neutron star properties using piecewise polytropic equations of state and assesses their compatibility with observations, emphasizing the potential of fractional moment of inertia and braking index as constraints.

Findings

Theoretical fractional moment of inertia estimates cannot fully explain pulsar glitches.

Braking index calculations deviate from observed data in simple models.

Future observations may constrain neutron star equations of state.

Abstract

We utilise the phenomenologically parameterized piecewise polytropic equations of state to study various neutron star properties. We investigate the compliance of these equations of state with several astronomical observations. We also demonstrate that the theoretical estimates of the fractional moment of inertia cannot explain all the pulsar glitches observed. We model the crust as a solid spheroidal shell to calculate the fractional moment of inertia of fast-spinning neutron stars. We also show that the braking index obtained in a simple magnetic dipole radiation model with a varying moment of inertia deviates significantly from the observed data. Future developments in both theory and observations may allow us to use the fractional moment of inertia and braking index as observational constraints for neutron star equation of state.