R-modes in the ocean of a magnetic neutron star

Abstract

We study the dynamics of r-modes in the ocean of a magnetic neutron star. We modeled the star's ocean with a spherical rotating thin shell and assumed that the magnetic field symmetry axis is not aligned to the shell's spin axis. In the magnetohydrodynamic approximation, we calculate the frequency of $\ell =m$ r-modes in the shell of an incompressible fluid. Different r-modes with $\ell$ and $\ell \pm 2$ are coupled by the {\it inclined} magnetic field. Kinematical secular effects for the motion of a fluid element in the shell undergoing $\ell =m=2$ r-mode are studied. The magnetic corrected drift velocity of a given fluid element undergoing the $\ell =m$ r-mode oscillations is obtained. The magnetic field increases the magnitude of the fluid drift produced by the r-mode drift velocity, the high-$\ell$ modes in the ocean fluid will damp faster than the low-$\ell$ ones.

24 pages, 5 figures, to appear in ApJ, v574 n2 August 1, 2002 issue

References in corpus (3)

• Nonlinear mode coupling in rotating stars and the r-mode instability in neutron stars
• Properties of r modes in rotating magnetic neutron stars. I. Kinematic Secular Effects and Magnetic Evolution Equations
• Properties of r modes in rotating magnetic neutron stars. II. Evolution of the r modes and stellar magnetic field

Cited by in corpus (5)

• Nonlinear Development of the R Mode Instability and the Maximum Rotation Rate of Neutron Stars
• Differential rotation of the unstable nonlinear r-modes
• The effect of magnetic fields on the r-modes of slowly rotating relativistic neutron stars
• Limits on Magnetic Field Amplification from the r-Mode Instability
• The Role of r-Modes in Pulsar Spin-down, Pulsar Timing, and Gravitational Waves