Free Energy of Anisotropic Strangeon Stars

TL;DR

This paper investigates the elastic and gravitational free energy of anisotropic solid strangeon stars, suggesting they can release enormous energy through starquakes, which may explain energetic astrophysical phenomena.

Contribution

It introduces two anisotropic models within general relativity to calculate free energy in solid strangeon stars, highlighting their potential for large energy release without strong magnetic fields.

Findings

Huge free energy (> 10^{46} erg) can be released via starquakes.

Small anisotropy (∼10^{-4}) is sufficient for significant energy release.

Solid strangeon stars could power energetic astrophysical events.

Abstract

Can pulsar-like compact objects release further huge free energy besides the kinematic energy of rotation? This is actually relevant to the equation of state of cold supra-nuclear matter, which is still under hot debate. Enormous energy is surely needed to understand various observations, such as $\gamma-$ray bursts, fast radio bursts and soft $\gamma-$ray repeaters. In this paper, the elastic/gravitational free energy of solid strangeon star is revisited for strangeon stars, with two anisotropic models to calculate in general relativity. It is found that huge free energy (> $10^{46}$ erg) could be released via starquakes, given an extremely small anisotropy ($(p_{\rm t}-p_{\rm r})/p_{\rm r} \sim 10^{-4}$, with $p_{\rm t}$/$p_{\rm r}$ the tangential/radial pressure), implying pulsar-like stars could have great potential of free energy release without extremely strong magnetic fields in solid strangeon star model.