Frequency spectrum of gravitational radiation from global hydromagnetic oscillations of a magnetically confined mountain on an accreting neutron star

Abstract

Recent time-dependent, ideal-magnetohydrodynamic (ideal-MHD) simulations of polar magnetic burial in accreting neutron stars have demonstrated that stable, magnetically confined mountains form at the magnetic poles, emitting gravitational waves at $f_{\ast }$ (stellar spin frequency) and $2f_{\ast }$. Global MHD oscillations of the mountain, whether natural or stochastically driven, act to modulate the gravitational wave signal, creating broad sidebands (full-width half-maximum $\sim 0.2f_{\ast }$) in the frequency spectrum around $f_{\ast }$ and $2f_{\ast }$. The oscillations can enhance the signal-to-noise ratio achieved by a long-baseline interferometer with coherent matched filtering by up to 15 per cent, depending on where $f_{\ast }$ lies relative to the noise curve minimum. Coherent, multi-detector searches for continuous waves from nonaxisymmetric pulsars should be tailored accordingly.

4 figures, accepted for publication in ApJ

References in corpus (4)

• Gravitational Radiation from an Accreting Millisecond Pulsar with a Magnetically Confined Mountain
• Burial of the polar magnetic field of an accreting neutron star. I. Self-consistent analytic and numerical equilibria
• Discovery of the Neutron Star Spin Frequency in EXO 0748-676
• The gravitational wave spectrum of non-axisymmetric, freely precessing neutron stars

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