General Relativistic Magnetospheres of Slowly Rotating and Oscillating Magnetized Neutron Stars

Abstract

We study the magnetosphere of a slowly rotating magnetized neutron star subject to toroidal oscillations in the relativistic regime. Under the assumption of a zero inclination angle between the magnetic moment and the angular momentum of the star, we analyze the Goldreich-Julian charge density and derive a second-order differential equation for the electrostatic potential. The analytical solution of this equation in the polar cap region of the magnetosphere shows the modification induced by stellar toroidal oscillations on the accelerating electric field and on the charge density. We also find that, after decomposing the oscillation velocity in terms of spherical harmonics, the first few modes with $m=0,1$ are responsible for energy losses that are almost linearly dependent on the amplitude of the oscillation and that, for the mode $(l,m)=(2,1)$, can be a factor $\sim 8$ larger than the rotational energy losses, even for a velocity oscillation amplitude at the star surface as small as $\eta =0.05\Omega R$. The results obtained in this paper clarify the extent to which stellar oscillations are reflected in the time variation of the physical properties at the surface of the rotating neutron star, mainly by showing the existence of a relation between $P\dot{P}$ and the oscillation amplitude. Finally, we propose a qualitative model for the explanation of the phenomenology of intermittent pulsars in terms of stellar oscillations that are periodically excited by star glitches.

13 pages, 4 figures, submitted to MNRAS

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Cited by in corpus (13)

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• Evidence for an abundant old population of Galactic ultra long period magnetars and implications for fast radio bursts
• General-relativistic force-free pulsar magnetospheres
• Electromagnetic fields of slowly rotating magnetized compact stars in conformal gravity
• Oscillation Driven Magnetospheric Activity In Pulsars
• Explaining radio emission of magnetars via rotating and oscillating magnetospheres of neutron stars
• Multipolar electromagnetic fields around neutron stars: general-relativistic vacuum solutions
• Electromagnetic fields in the exterior of an oscillating relativistic star -- II. Electromagnetic damping
• Particle acceleration in the polar cap region of an oscillating neutron star
• Explaining the subpulse drift velocity of pulsar magnetosphere within the space-charge limited flow model
• Numerical simulation of oscillating magnetospheres with resistive electrodynamics
• Twisted magnetosphere with quadrupolar fields in the exterior of a neutron star
• Methods for relativistic self-gravitating fluids: From binary neutron stars to black hole-disks and magnetized rotating neutron stars