Model pulsar magnetospheres: the perpendicular rotator

Mestel, L.; Panagi, P. M.; Shibata, Shinpei

doi:10.1046/j.1365-8711.1999.02827.x

Cited by 32 publications

(26 citation statements)

References 24 publications

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“…However, this is not so if the pulsar magnetosphere is filled with plasma and there is no longitudinal current in the magnetosphere. As was shown by Beskin, Gurevich & Istomin (1993) and Mestel, Panagi & Shibata (1999), in this case the Poynting flux through the light cylinder is equal to zero. Indeed, as the ideal conductivity condition is applicable not only inside the neutron star but outside as well there is no magnetic field discontinuity at the star surface.…”

Section: Magneto-dipole Losssupporting

confidence: 62%

On the role of the current loss in radio pulsar evolution

Бескин

Nokhrina

2007

Astrophys Space Sci

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The aim of this article is to draw attention to the importance of the electric current loss in the energy output of radio pulsars. We remind that even the losses attributed to the magneto-dipole radiation of a pulsar in vacuum can be written as a result of an Ampere force action of the electric currens flowing over the neutron star surface (Michel 1991;Beskin, Gurevich & Istomin 1993). It is this force that is responsible for the transfer of angular momentum of a neutron star to an outgoing magnetodipole wave. If a pulsar is surrounded by plasma, and there is no longitudinal current in its magnetosphere, there is no energy loss (Beskin, Gurevich & Istomin 1993;Mestel, Panagi & Shibata 1999). It is the longitudinal current closing within the pulsar polar cap that exerts the retardation torque acting on the neutron star. This torque can be determined if the structure of longitudinal current is known. Here we remind of the solution by Beskin, Gurevitch & Istomin (1993) and discuss the validity of such an assumption. The behavior of the recently observed "part-time job" pulsar B1931+24 can be naturally explained within the model of current loss while the magneto-dipole model faces difficulties. The first idea to explain the energy loss of radio pulsars was to consider the magneto-dipole radiation (Pacini 1967). Indeed, the magneto-dipole formula gives for the radiation powerwhere χ is the angle between rotational and magnetic axis, R is a neutron star radius ∼ 10 km, and Ω is a pulsar angular velocity. This formula explains pulsar activity and observed energy loss for expected large magnetic field near the surface B 0 ∼ 10 12 Gs. Let us recall that the physical reason of such energy loss is the action of the torque exerted on the pulsar by the Ampere force of the electric currens flowing over the neutron star surface (Istomin 2005). The electric and magnetic fields in the outgoing magneto-dipole wave in vacuum can be found by solving the wave equations ∇ 2 B + Ω 2 /c 2 B = 0 and ∇ 2 E + Ω 2 /c 2 E = 0 with the boundary conditions stated as the fields corresponding components E t and B n being continuous through the neutron star surface. Inside the star one can consider magnetic field as homogeneous, and find the corresponding electric field using the frozen-in condition. As a result, the full solution will give us the discontinuity of {B t } and {E n } attributed to the surface charge σ s and the surface current J s = c 4π [n, {B}]. The Ampere force exerts the torqueon the neutron star. The energy loss of a pulsar due to this torque is equal to (1). Thus, it is the surface current that is responsible for the angular momentum transform from a neutron star to an outgoing magnetodipole wave (Michel 1991;Beskin, Gurevich & Istomin 1993). A pulsar in vacuum loses its rotational energy due to angular momentum transform to the electromagnetic

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Section: Magneto-dipole Losssupporting

confidence: 62%

On the role of the current loss in radio pulsar evolution

Бескин

Nokhrina

2007

Astrophys Space Sci

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“…Taking into account that dΩ = sin θdθdφ ≈ θdθdφ, (18) into (19) and integrate over φ and ξ; this yields the expression for the vector K cur :…”

Section: Current Braking Mechanismmentioning

confidence: 99%

“…An example when this cannot be done, and, moreover, there are no magnetic-dipole losses whatsoever, was demonstrated in [17,19] (see also [1]). However, the results of observations of the pulsar B1931+24 [7] probably provide evidence not only that pulsars undergo magnetic-dipole losses, but also that these can be added to current losses.…”

Section: Shape and Radius Of The Pulsar Tube Cross-sectionmentioning

confidence: 99%

Evolution of the angle between the magnetic moment and the rotation axis of radio pulsars

2009

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Abstract-It is shown that, when angular-momentum losses of a radio pulsar are represented as a sum of magnetic-dipole and current losses, the angle between the magnetic moment and rotation axis of the radio pulsar tends to some equilibrium value (near 45• ). This process takes place on a timescale of the order of the pulsar's characteristic age. Taking into account the non-dipolarity of the pulsar's magnetic field changes this equilibrium angle.PACS numbers: 97.60.Gb

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“…As was pointed out by many authors (Beskin et al 1993;Mestel et al 1999;Beskin & Nokhrina 2007) that the dipole braking is not efficient when the pulsar is surrounded by plasma, and the observed profile evolution of the Crab pulsar implies that χ is drifting towards 90…”

Section: The Equivalent Magnetic Field When the Current Loss Torque Imentioning

confidence: 89%

The evolution of the magnetic inclination angle as an explanation of the long term red timing-noise of pulsars

Zhang

2015

Mon. Not. R. Astron. Soc.

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We study the possibility that the long term red timing-noise in pulsars originates from the evolution of the magnetic inclination angle χ. The braking torque under consideration is a combination of the dipole radiation and the current loss. We find that the evolution of χ can give rise to extra cubic and fourth-order polynomial terms in the timing residuals. These two terms are determined by the efficiency of the dipole radiation, the relative electric-current density in the pulsar tube and χ. The following observation facts can be explained with this model: a) young pulsars have positivë ν; b) old pulsars can have both positive and negativeν; c) the absolute values ofν are proportional to −ν; d) the absolute values of the braking indices are proportional to the characteristic ages of pulsars. If the evolution of χ is purely due to rotation kinematics, then it can not explain the pulsars with braking index less than 3, and thus the intrinsic change of the magnetic field is needed in this case. Comparing the model with observations, we conclude that the drift direction of χ might oscillate many times during the lifetime of a pulsar. The evolution of χ is not sufficient to explain the rotation behavior of the Crab pulsar, because the observed χ andχ are inconsistent with the values indicated from the timing residuals using this model.

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Model pulsar magnetospheres: the perpendicular rotator

Cited by 32 publications

References 24 publications

On the role of the current loss in radio pulsar evolution

On the role of the current loss in radio pulsar evolution

Evolution of the angle between the magnetic moment and the rotation axis of radio pulsars

The evolution of the magnetic inclination angle as an explanation of the long term red timing-noise of pulsars

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