Coupling of Radial and Non-Radial Oscillations of Neutron Stars

Abstract

This is a progress report on our study of the coupling of first-order radial and non-radial relativistic perturbations of a static spherical star. Our goal is to investigate the effects of this coupling on the gravitational wave signal of neutron stars. In particular, we are looking for the existence of resonances and parametric amplifications, changes in the damping time of non-radial oscillations, etc. To that end, we have developed a formalism that introduces gauge invariant quantities to describe the coupling. Their equations have the same structure as the equations for first-order non-radial perturbations plus some source terms, which makes them very appealing for time domain studies.

Cosmic electromagnetic fields due to perturbations in the gravitational field

“…We then proceed by adopting a two parameter perturbative framework [28][29][30][31][32]. Fundamentally, this consists of separately parametrizing the gravitational and Maxwell field perturbations in two expansion parameters ǫ g and ǫB, representing the amplitudes of the gravitational and electromagnetic field perturbations, respectively [18,22,29].…”