Free Energy of Anisotropic Strangeon Stars

Abstract

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 γ-ray bursts, fast radio bursts and soft γ-ray repeaters. In this paper, the elastic/gravitational free energy of solid strangeon stars is revisited for strangeon stars, with two anisotropic models to calculate in general relativity. It is found that huge free energy (>1046 erg) could be released via starquakes, given an extremely small anisotropy ((p t − p r)/p r ∼ 10−4, with p t/p r the tangential/radial pressure), implying that pulsar-like stars could have great potential of free energy release without extremely strong magnetic fields in the solid strangeon star model.