Constraining equation-of-state groups from <i>g</i>-mode asteroseismology
Hao-Jui Kuan, C. Krüger, Arthur G. Suvorov, Kostas D. Kokkotas
Abstract
ABSTRACT Buoyancy-restored modes inside neutron stars depend sensitively on both the microphysical (e.g. composition and entropy gradients) and macrophysical (e.g. stellar mass and radius) properties of the star. Asteroseismology efforts for g modes are therefore particularly promising avenues for recovering information concerning the nuclear equation of state. In this work, it is shown that the overall low-temperature g-space consists of multiple groups corresponding to different classes of equation of state (e.g. hadronic versus hybrid). This is in contrast to the case of pressure-driven modes, for example, which tend to follow a universal relation regardless of microphysical considerations. Using a wide library of currently viable equations of state, perturbations of static, stratified stars are calculated in general relativity to demonstrate in particular how g-space groupings can be classified according to the mean mass density, temperature, central speed of sound, and tidal deformability. Considering present and future observations regarding gravitational waves, accretion outbursts, quasi-periodic oscillations, and precursor flashes from gamma-ray bursts, it is shown how one might determine which group the g modes belong to.