paper

R-Mode Oscillations in Rotating Magnetic Neutron Stars

arXiv:astro-ph/9911188 · doi:10.1086/312539

Abstract

We show that r-mode oscillations distort the magnetic fields of neutron stars and that their occurrence is likely to be limited by this interaction. If the field is gtrsim 10^{16} (Omega/Omega_B) G, where Omega and Omega_B are the angular velocities of the star and at which mass shedding occurs, r-mode oscillations cannot occur. Much weaker fields will prevent gravitational radiation from exciting r-mode oscillations or damp them on a relatively short timescale by extracting energy from the modes faster than gravitational wave emission can pump energy into them. For example, a 10^{10} G poloidal magnetic field that threads the star's superconducting core is likely to prevent the ell=2 mode from being excited unless Omega exceeds 0.35 Omega_B. If Omega is larger than 0.35 Omega_B initially, the ell=2 mode may be excited but is likely to decay rapidly once Omega falls below 0.35 Omega_B, which happens in lesssim 15^d if the saturation amplitude is gtrsim 0.1. The r-mode oscillations may play an important role in determining the structure of neutron star magnetic fields.

4 pages, 1 postscript figure, uses emulateapj; submitted to ApJ Letters 1999 Nov 8; accepted 2000 Jan 25; this version is essentially identical to the original version except that Figure 2 was deleted in order to fit within the ApJ Letters page limit

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