Elastodynamical properties of nuclear matter from the observed activity of neutron stars

Abstract

The results of studies devoted to describing the large-scale motions of the nuclear matter of neutron stars are reviewed. The approach is based on the idea that stellar nuclear matter is an elastic Fermi continuum possessing the properties of a compensated magneto-active plasma. The fundamental dynamical equations of motion of self-gravitating nuclear matter are taken to be the equations of nuclear elastodynamics, formulated in the macroscopic theory of nuclear collective processes. A variational method is presented for calculating the frequencies of gravitational-elastic spheroidal ( s -mode) and torsional ( t -mode) vibrations of a neutron star, and the star’s stability with respect to linear deformations is studied. The effectiveness of the elastodynamical method is illustrated by calculations of the periods of global gravitational elastic vibrations within the standard homogeneous model, and also for a family of realistic models of neutron stars, constructed on the basis of the relativistic equation of gravitational equilibrium and the nuclear-matter equations of state taking into account the heterophase nature of the nuclear statistical equilibrium. The motions of the magnetized Ae phase of the neutron-star matter are described using the magneto-hydrodynamical approach, which is used to calculate the frequencies of toroidal and poloidal Alfven oscillations. It is emphasized that magneto-plasma vibrations can significantly affect the electromagnetic activity of pulsars.