Magnetosphere of the rotation-powered pulsar - A DC circuit model

Shibata, Shinpei

doi:10.1086/170423

Cited by 42 publications

(30 citation statements)

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“…The analogy has been extended to include resistivity, capacitance, and inductance in linear circuits (e.g., Shibata 1991;Jessner et al 2001;Xu et al 2006) which, in principle, could show oscillations with well-defined timescales. However, nonlinear circuits can have metastable states with broad, Markov-type durations when state switching occurs from noise-like voltage variations.…”

Section: Circuit Analogsmentioning

confidence: 99%

Pulsar State Switching From Markov Transitions and Stochastic Resonance

Cordes

2013

ApJ

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Markov processes are shown to be consistent with metastable states seen in pulsar phenomena, including intensity nulling, pulse-shape mode changes, subpulse drift rates, spin-down rates, and X-ray emission, based on the typically broad and monotonic distributions of state lifetimes. Markovianity implies a nonlinear magnetospheric system in which state changes occur stochastically, corresponding to transitions between local minima in an effective potential. State durations (though not transition times) are thus largely decoupled from the characteristic timescales of various magnetospheric processes. Dyadic states are common but some objects show at least four states with some transitions forbidden. Another case is the long-term intermittent pulsar B1931+24 that has binary radio-emission and torque states with wide, but non-monotonic duration distributions. It also shows a quasi-period of 38 ± 5 days in a 13 yr time sequence, suggesting stochastic resonance in a Markov system with a forcing function that could be strictly periodic or quasi-periodic. Nonlinear phenomena are associated with time-dependent activity in the acceleration region near each magnetic polar cap. The polar-cap diode is altered by feedback from the outer magnetosphere and by return currents from the equatorial region outside the light cylinder that may also cause the neutron star to episodically charge and discharge. Orbital perturbations of a disk or current sheet provide a natural periodicity for the forcing function in the stochastic-resonance interpretation of B1931+24. Disk dynamics may introduce additional timescales in observed phenomena. Future work can test the Markov interpretation, identify which pulsar types have a propensity for state changes, and clarify the role of selection effects.

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Section: Circuit Analogsmentioning

confidence: 99%

Pulsar State Switching From Markov Transitions and Stochastic Resonance

Cordes

2013

ApJ

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“…The resulting additional electrostatic field screens out the initial E k above the PFF (e.g., Fawley et al 1977;Arons & Scharlemann 1979;Shibata et al 1998). In some pulsar models pairs are also assumed to be produced in an ''outer gap'' (Cheng et al 1986), and current conservation can be achieved by the currents through the inner and outer gaps being part of a global circuit (Shibata 1991). More recent models differ quantitatively, rather than qualitatively, from earlier models in that the Lorentz factors of the secondary pairs are smaller (Zhang & Harding 2000;Hibschman & Arons 2001;Arendt & Eilek 2002) and the pair creation is over a more extensive region, with the heights of the inner and outer gaps perhaps overlapping (Shibata et al 2002).…”

Section: Introductionmentioning

confidence: 99%

Large‐Amplitude, Pair‐creating Oscillations in Pulsar and Black Hole Magnetospheres

Levinson

Melrose

Judge

et al. 2005

ApJ

103

136

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A time-dependent model for pair creation in a pulsar magnetosphere is developed in which the parallel electric field oscillates with large amplitude. Electrons and positrons are accelerated periodically, and the amplitude of the oscillations is assumed to be large enough to cause creation of upgoing and downgoing pairs at different phases of the oscillation. With a charge-starved initial condition, we find that the oscillations result in bursts of pair creation in which the pair density rises exponentially with time. The pair density saturates at N AE ' E 2 0 /(8 m e c 2 À thr ), where E 0 is the parallel electric field in the charge-starved initial state and À thr is the Lorentz factor for effective pair creation. The frequency of oscillations following the pair creation burst is given roughly by ! osc ¼ eE 0 /(8m e cÀ thr ). A positive feedback keeps the system stable, such that the average pair creation rate balances the loss rate due to pairs escaping the magnetosphere.

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“…As noted, the value of the current is fixed by the far boundary condition. A larger current would yield |JE||| increasing outwards; a smaller current would yield a quasi-GJ system, with v < c (no Mestei relativistic acceleration), and with the spatial oscillations found by Mestei k Pryce (1985), Shibata (1991) and Mestei k Shibata (1995). The curvature of the field lines does not come into the MT discussion.…”

Section: Gmdr 2 J Fr G \[Rmentioning

confidence: 90%