Electromagnetic damping of neutron star oscillations

McDermott, P. N.; Savedoff, M. P.; Horn, H. M. van; Zweibel, Ellen G.; Hansen, C. J.

doi:10.1086/162152

Cited by 19 publications

(22 citation statements)

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“…a sudden change in the rotational period), propagate into the magnetosphere, thus affecting the acceleration properties in the polar cap region. The idea that neutron star oscillations may induce high energy emission in neutron star magnetospheres was developed in a series of papers by Timokhin and collaborators (Timokhin et al 2000;Timokhin 2007;Timokhin et al 2008), after the first pioneering investigations by McDermott et al (1984), Muslimov & Tsygan (1986), and Rezzolla & Ahmedov (2004), who considered the case of an oscillating neutron star in a vacuum. A few years ago we initiated a program aimed at assessing the impact of toroidal oscillations of the star surface on the properties of the external magnetosphere, with general relativistic effects properly taken into account.…”

Section: Introductionmentioning

confidence: 99%

Particle acceleration in the polar cap region of an oscillating neutron star

Zanotti

Morozova

Ahmedov

2012

A&A

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Aims. We revisit particle acceleration in the polar cap region of a neutron star by taking into account both general relativistic effects and the presence of toroidal oscillations at the star surface. In particular, we address the question of whether toroidal oscillations at the stellar surface can affect the acceleration properties in the polar cap. Methods. We solve numerically the relativistic electrodynamics equations in the stationary regime, focusing on the computation of the Lorentz factor of a space-charge-limited electron flow accelerated in the polar cap region of a rotating and oscillating pulsar. To this extent, we adopt the correct expression of the general relativistic Goldreich-Julian charge density in the presence of toroidal oscillations. Results. Depending on the ratio of the actual charge density of the pulsar magnetosphere to the Goldreich-Julian charge density, we distinguish two different regimes of the Lorentz factor of the particle flow, namely an oscillatory regime produced for sub-GJ current density configurations, which does not produce an efficient acceleration, and a true accelerating regime for super-GJ current density configurations. We find that star oscillations may be responsible for a significant asymmetry in the pulse profile that depends on the orientation of the oscillations with respect to the pulsar magnetic field. In particular, significant enhancements of the Lorentz factor are produced by stellar oscillations in the super-GJ current density regime.

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Section: Introductionmentioning

confidence: 99%

Particle acceleration in the polar cap region of an oscillating neutron star

Zanotti

Morozova

Ahmedov

2012

A&A

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“…We consider two dissipation mechanisms: one is via the non‐linear (in the pulsation amplitude) bulk viscosity in the stellar core and the other is due to the shear viscosity. We neglect other possible dissipation mechanisms, in particular, the damping of pulsations induced by the star magnetic field (as discussed in detail by McDermott et al 1984 and by McDermott, van Horn & Hansen 1988). The magnetic field is assumed to be low.…”

Section: Introductionmentioning

confidence: 99%

Thermal evolution of a pulsating neutron star

Gusakov

Yakovlev

Gnedin

2005

Monthly Notices of the Royal Astronomical Society

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We have derived a set of equations to describe the thermal evolution of a neutron star which undergoes small‐amplitude radial pulsations. We have taken into account, within the framework of the general theory of relativity, the pulsation damping due to the bulk and shear viscosity and the accompanying heating of the star. The neutrino emission of a pulsating non‐superfluid star and its heating due to the bulk viscosity are calculated assuming that both processes are determined by the non‐equilibrium modified Urca process. Analytical and numerical solutions to the set of equations of the stellar evolution are obtained for linear and strongly non‐linear deviations from beta‐equilibrium. It is shown that a pulsating star may be heated to very high temperatures, while the pulsations damp very slowly with time as long as the damping is determined by the bulk viscosity (a power‐law damping over 100–1000 yr). The contribution of the shear viscosity to the damping becomes important in a rather cool star with a low pulsation energy.

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“…The first one has focused on the study of the eigenfrequencies and eigenfunctions of selected modes of magnetized neutron stars in general relativity (e.g., Messios et al 2001;Chugunov & Yakovlev 2005;Piro 2005;Sotani et al 2007;Glampedakis et al 2006;Samuelsson & Andersson 2007;Vavoulidis et al 2007)]. The second one, instead, has focused its attention on the properties of the electromagnetic fields from near the stellar surface up to the wave-zone (e.g., McDermott et al 1984;Muslimov & Tsygan 1986;Muslimov & Harding 1997;Konno et al 1999Timokhin et al 2000;Rezzolla et al 2001b,a;Kojima & Okita 2004;Rezzolla & Ahmedov 2004) 2 . The work reported in this paper belongs to the second class of studies and concentrates on calculating explicit expressions for the electromagnetic fields generated by radial, toroidal and spheroidal oscillations of the stellar surface.…”

Section: Introductionmentioning

confidence: 99%

Electromagnetic fields in the exterior of an oscillating relativistic star – II. Electromagnetic damping

Rezzolla

Ahmedov

2016

Mon. Not. R. Astron. Soc.

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An important issue in the asteroseismology of compact and magnetized stars is the determination of the dissipation mechanism which is most efficient in damping the oscillations when these are produced. In a linear regime and for low-multipolarity modes these mechanisms are confined to either gravitational-wave or electromagnetic losses. We here consider the latter and compute the energy losses in the form of Poynting fluxes, Joule heating and Ohmic dissipation in a relativistic oscillating spherical star with a dipolar magnetic field in vacuum. While this approach is not particularly realistic for rapidly rotating stars, it has the advantage that it is fully analytic and that it provides expressions for the electric and magnetic fields produced by the most common modes of oscillation both in the vicinity of the star and far away from it. In this way we revisit and extend to a relativistic context the classical estimates of McDermott et al. Overall, we find that general-relativistic corrections lead to electromagnetic damping time-scales that are at least one order of magnitude smaller than in Newtonian gravity. Furthermore, with the only exception of g (gravity) modes, we find that f (fundamental), p (pressure), i (interface) and s (shear) modes are suppressed more efficiently by gravitational losses than by electromagnetic ones.

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Electromagnetic damping of neutron star oscillations

Cited by 19 publications

References 0 publications

Particle acceleration in the polar cap region of an oscillating neutron star

Particle acceleration in the polar cap region of an oscillating neutron star

Thermal evolution of a pulsating neutron star

Electromagnetic fields in the exterior of an oscillating relativistic star – II. Electromagnetic damping

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