Pulsar Magnetospheric Emission Mapping: Images and Implications of Polar Cap Weather

Deshpande, A. A.; Rankin, Joanna M.

doi:10.1086/307862

Cited by 162 publications

(234 citation statements)

References 22 publications

(27 reference statements)

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“…In the model, radio emission is the result of the secondary particles scattering o † "" low-frequency waves.ÏÏ The waves are assumed to be produced by either the breaking down of the vacuum polar gap or other sorts of short time oscillations or microinstabilities 1996). The gap sparking may exist (Bjornsson above the polar cap, as shown by new observations by Deshpande & Rankin (1999) and by Vivekanand & Joshi (1999). If so, there must be low-frequency waves emitted by such sparking.…”

Section: Introductionmentioning

confidence: 93%

“…The radius of a sparking spot was assumed to have the same scale as the inner gap height (Gil 1998), which Deshpande & Rankin (1999) estimated to be about 10 m. We took this value in the following simulations, but we have found that changing this dimensional size does not a †ect our results. We also assumed that the number density of particles in a bunch n e has a maximum in the center and declines toward the edge.…”

Section: T Ransient Beam From a Bunch Of Particles : Simulationmentioning

confidence: 99%

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An Inverse Compton Scattering Model of Pulsar Emission. III. Polarization

Liu

Han

et al. 2000

ApJ

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Qiao and his collaborators recently proposed an inverse Compton scattering model to explain radio emission from pulsars. In this paper, we investigate the polarization properties of pulsar emission in the model. First of all, using the lower frequency approximation, we derived the analytical amplitude of the inverse Compton scattered wave of a single electron in a strong magnetic Ðeld. We found that the outgoing radio emission of a single relativistic electron scattering o † the "" low-frequency waves ÏÏ produced by gap sparking should be linearly polarized and have no circular polarization at all. However, considering the coherency of the emission from a bunch of electrons, we found that the outgoing radiation from the inner part of the emission beam, i.e., that from the lower emission altitudes, preferentially has to have circular polarization. Computer simulations show that the polarization properties, such as the sense reversal of circular polarization near the pulse center, the S-shape of position angle swing of the linear polarization, and a strong linear polarization in conal components, can be reproduced in the ICS model.

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Section: Introductionmentioning

confidence: 93%

Section: T Ransient Beam From a Bunch Of Particles : Simulationmentioning

confidence: 99%

An Inverse Compton Scattering Model of Pulsar Emission. III. Polarization

Liu

Han

et al. 2000

ApJ

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“…Another complication is that a pulse is often composed of several identiÐable components, some of which can be polarized in the orthogonal mode (a result of propagation e †ects in the magnetosphere) obscuring the "" true ÏÏ polarization. Furthermore, the pulse itself might not even contain an identiÐable core component, being composed instead of emission from random patches within a cone (e.g., Lyne & Manchester 1988 ;Manchester 1995 ;Deshpande & Rankin 1999). Accordingly, measurements of are rarely attempted, ( 0 measurements of a are rarely trusted, and measurements of f are rarely questioned.…”

Section: Fig 8è(a)mentioning

confidence: 99%

Vela Pulsar and Its Synchrotron Nebula

Helfand

Gotthelf

Halpern

2001

ApJ

289

305

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We present high-resolution Chandra X-ray observations of PSR B0833[45, the 89 ms pulsar associated with the Vela supernova remnant. We have acquired two observations separated by 1 month to search for changes in the pulsar and its environment following an extreme glitch in its rotation frequency. We Ðnd a well-resolved nebula with a toroidal morphology remarkably similar to that observed in the Crab Nebula, along with an axial Crab-like jet. Between the two observations, taken D3 ] 105 s and D3 ] 106 s after the glitch, the Ñux from the pulsar is found to be steady to within 0.75% ; the 3 p limit on the fractional increase in the pulsarÏs X-ray Ñux is of the inferred glitch energy. We use [10~5 this limit to constrain parameters of glitch models and neutron star structure. We do Ðnd a signiÐcant increase in the Ñux of the nebulaÏs outer arc ; if associated with the glitch, the inferred propagation velocity is similar to that seen in the brightening of the Crab Nebula wisps. We propose an explana-Z0.7c, tion for the X-ray structure of the Vela synchrotron nebula based on a model originally developed for the Crab Nebula. In this model, the bright X-ray arcs are the shocked termination of a relativistic equatorial pulsar wind that is contained within the surrounding kidney-bean shaped synchrotron nebula comprising the postshock, but still relativistic, Ñow. In a departure from the Crab model, the magnetization parameter p of the Vela pulsar wind is allowed to be of order unity ; this is consistent with the simplest MHD transport of magnetic Ðeld from the pulsar to the nebula, where B ¹ 4 ] 10~4 G. The inclination angle of the axis of the equatorial torus with respect to the line of sight is identical to that of the rotation axis of the pulsar as previously measured from the polarization of the radio pulse. The projection of the rotation axis on the sky may also be close to the direction of proper motion of the pulsar if previous radio measurements were confused by orthogonal-mode polarized components. We review e †ects that may enhance the probability of alignment between the spin axis and space velocity of a pulsar, and speculate that short-period, slowly moving pulsars are just the ones best-suited to producing synchrotron nebulae with such aligned structures. Previous interpretations of the compact Vela nebula as a bow-shock in a very weakly magnetized wind su †ered from data of inadequate spatial resolution and less plausible physical assumptions.

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“…Deshpande & Rankin (1999) demonstrated clearly that the non-corotating subbeams associated with drifting subpulses actually lag the stellar rotation. This finding strenghtens the VG plasma E × B drift hypothesis.…”

Section: Introductionmentioning

confidence: 95%

Vacuum gap model for PSR B0943+10

Gil

Melikidze

Mitra

2002

A&A

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Abstract. PSR B0943+10 is known to show remarkably stable drifting subpulses, which can be interpreted in terms of a circumferential motion of 20 sparks, each completing one circulation around the periphery of the polar cap in 37 pulsar periods. We use this observational constraint and argue that the vacuum gap model can adequately describe the observed drift patterns. Further we demonstrate that only the presence of strong non-dipolar surface magnetic field can favor such vacuum gap formation. Subsequently, for the first time we are able to constrain the parameters of the surface magnetic field, and model the expected magnetic structure on the polar cap of PSR B0943+10 considering the inverse Compton scattering photon dominated vacuum gap.

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Pulsar Magnetospheric Emission Mapping: Images and Implications of Polar Cap Weather

Cited by 162 publications

References 22 publications

An Inverse Compton Scattering Model of Pulsar Emission. III. Polarization

An Inverse Compton Scattering Model of Pulsar Emission. III. Polarization

Vela Pulsar and Its Synchrotron Nebula

Vacuum gap model for PSR B0943+10

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