Free Energy of Anisotropic Strangeon Stars

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.