Gravitational Wave asteroseismology revisited

Abstract

The frequencies and damping times of the non radial oscillations of neutron stars are computed for a set of recently proposed equations of state (EOS) which describe matter at supranuclear densites. These EOS are obtained within two different approaches, the nonrelativistic nuclear many-body theory and the relativistic mean field theory, that model hadronic interactions in different ways leading to different composition and dynamics. Being the non radial oscillations associated to the emission of gravitational waves, we fit the eigenfrequencies of the fundamental mode and of the first pressure and gravitational-wave mode (polar and axial) with appropriate functions of the mass and radius of the star, comparing the fits, when available, with those obtained by Andersson and Kokkotas in 1998. We show that the identification in the spectrum of a detected gravitational signal of a sharp pulse corresponding to the excitation of the fundamental mode or of the first p-mode, combined with the knowledge of the mass of the star - the only observable on which we may have reliable information - would allow to gain interesting information on the composition of the inner core. We further discuss the detectability of these signals by gravitational detectors.