Chebyshev Based Spectral Representations of Neutron-Star Equations of State

TL;DR

This paper develops and evaluates Chebyshev polynomial spectral representations for neutron-star equations of state, demonstrating their high accuracy and convergence across various models and phase transition scenarios.

Contribution

It introduces Chebyshev polynomial spectral expansions for neutron-star equations of state and compares their accuracy to previous methods, showing improved convergence and precision.

Findings

Chebyshev spectral representations are convergent for diverse equations of state.

They outperform power-law spectral representations in accuracy.

Pressure-based representations are more accurate than enthalpy-based ones.

Abstract

Causal parametric representations of neutron-star equations of state are constructed here using Chebyshev polynomial based spectral expansions. The accuracies of these representations are evaluated for a collection of model equations of state from a variety of nuclear-theory models and also a collection of equations of state with first- or second-order phase transitions of various sizes. These tests show that the Chebyshev based representations are convergent (even for equations of state with phase transitions) as the number of spectral basis functions is increased. This study finds that the Chebyshev based representations are generally more accurate than a previously studied power-law based spectral representation, and that pressure-based representations are generally more accurate than those based on enthalpy.