Representing Equations of State With Strong First-Order Phase Transitions

TL;DR

This paper investigates how well spectral and piecewise analytic methods can represent neutron star equations of state with strong first-order phase transitions, crucial for astrophysical modeling.

Contribution

It compares the accuracy of spectral and piecewise analytic representations for equations of state with strong phase transitions, revealing spectral methods generally perform better.

Findings

Spectral representations achieve higher accuracy than piecewise methods.

Both methods exhibit similar power-law convergence rates.

Models include phase transitions causing neutron star instabilities.

Abstract

Parametric representations of the high-density nuclear equation of state are used in constructing models for interpreting the astrophysical observations of neutron stars. This study explores how accurately equations of state with strong first-order phase transitions can be represented using spectral or piecewise analytic methods that assume no {\it{a priori}} knowledge of the location or the strength of the phase transition. The model equations of state used in this study have phase transitions strong enough to induce a gravitational instability that terminates the sequence of stable neutron stars. These equations of state also admit a second sequence of stable stars with core matter that has undergone this strong first-order phase transition (possibly driven by quark deconfinement). These results indicate that spectral representations generally achieve somewhat higher accuracy than piecewise analytic representations having the same number of parameters. Both types of representation show power-law convergence at approximately the same rate.