A relativistic model of pulsar polarization

Blaskiewicz, M.; Cordes, J. M.; Wasserman, Ira

doi:10.1086/169850

Cited by 301 publications

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“…It is becoming increasingly clear Ravi et al 2010) that for many young pulsars, especially the gamma-ray detected pulsars, the radio emission arises at a substantial fraction of the light cylinder radius, R LC . This in turn means that the polarization PA sweeps are offset significantly from the radio pulse (Blaskiewicz et al 1991), and that more subtle distortions in the PA sweep shape may occur. Self-consistent fitting using large radio altitudes should therefore lead to a shift in the inferred α and ζ values.…”

Section: Polarizationmentioning

confidence: 99%

PSRs J0248+6021 and J2240+5832: young pulsars in the northern Galactic plane

Theureau

Parent

Cognard

et al. 2010

A&A

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Context. Pulsars PSR J0248+6021 (with a rotation period P = 217 ms and spin-down powerĖ = 2.13 × 10 35 erg s −1 ) and PSR J2240+5832 (P = 140 ms,Ė = 2.12 × 10 35 erg s −1 ) were discovered in 1997 with the Nançay radio telescope during a northern Galactic plane survey, using the Navy-Berkeley Pulsar Processor (NBPP) filter bank. The GeV gamma-ray pulsations from both were discovered using the Fermi Large Area Telescope. Aims. We characterize the neutron star emission using radio and gamma-ray observations, and explore the rich environment of PSR J0248+6021. Methods. Twelve years of radio timing data, including glitches, with steadily improved instrumentation, such as the Berkeley-Orleans-Nançay pulsar backend, and a gamma-ray data set 2.6 times larger than previously published allow detailed investigations of these pulsars. Radio polarization data allow comparison with the geometry inferred from gamma-ray emission models. Results. The two pulsars resemble each other in both radio and gamma-ray data. Both are rare in having a single gamma-ray pulse offset far from the radio peak. The anomalously high dispersion measure for PSR J0248+6021 (DM = 370 pc cm −3 ) is most likely due to its being within the dense, giant HII region W5 in the Perseus arm at a distance of 2 kpc, as opposed to being beyond the edge of the Galaxy as obtained from models of average electron distributions. Its large transverse velocity and the low magnetic field along the line-of-sight favor this small distance. Neither gamma-ray, X-ray, nor optical data yield evidence of a pulsar wind nebula surrounding PSR J0248+6021. We report the discovery of gamma-ray pulsations from PSR J2240+5832. We argue that it could be in the outer arm, although slightly nearer than its DM-derived distance, but that it may be in the Perseus arm at half the distance. Conclusions. The energy flux and distance yield a gamma-ray luminosity for PSR J0248+6021 of L γ = (1.4 ± 0.3) × 10 34 erg s −1 . For PSR J2240+5832, we find either L γ = (7.9 ± 5.2) × 10 34 erg s −1 if the pulsar is in the outer arm, or L γ = (2.2 ± 1.7) × 10 34 erg s −1 for the Perseus arm. These luminosities are consistent with an L γ ∝ √Ė rule. Comparison of the gamma-ray pulse profiles with model predictions, including the constraints obtained from radio polarization data, implies outer magnetosphere emission. These two pulsars differ mainly in terms of their inclination angles and acceleration gap widths, which in turn explain the observed differences in the gamma-ray peak widths.

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Section: Polarizationmentioning

confidence: 99%

PSRs J0248+6021 and J2240+5832: young pulsars in the northern Galactic plane

Theureau

Parent

Cognard

et al. 2010

A&A

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“…A number exhibit PPA traverses that are readily fitted by the expected rotating-vector (RVM) model (Radhakrishnan & Cooke 1969) have helped us to understand these effects more fully [Mitra et al (2007); Smith et al (2013)], and we have found that intensity-dependent aberration/retardation (A/R, see Blaskiewicz et al 1991)-an effect first seen in the Vela pulsar (Krishnamohan & Downs 1983)-is also a major source of PPA-traverse distortion in cores. Figure 2 shows a clear case of this sort of depolarization and distortion of an otherwise nearly linear PPA traverse.…”

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confidence: 94%

Toward an Empirical Theory of Pulsar Emission. Xi. Understanding the Orientations of Pulsar Radiation and Supernova “Kicks”

Rankin

2015

ApJ

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Two entwined problems have remained unresolved since pulsars were discovered nearly 50 years ago: the orientation of their polarized emission relative to the emitting magnetic field and the direction of putative supernova "kicks' relative to their rotation axes. The rotational orientation of most pulsars can be inferred only from the ("fiducial') polarization angle of their radiation, when their beam points directly at the Earth and the emitting polar fluxtube field is to the rotation axis. Earlier studies have been unrevealing owing to the admixture of different types of radiation (core and conal, two polarization modes), producing both or ⊥ alignments. In this paper we analyze the some 50 pulsars having three characteristics: core radiation beams, reliable absolute polarimetry, and accurate proper motions. The "fiducial' polarization angle of the core emission, we then find, is usually oriented ⊥ to the proper-motion direction on the sky. As the primary core emission is polarized ⊥ to the projected magnetic field in Vela and other pulsars where X-ray imaging reveals the orientation, this shows that the proper motions usually lie to the rotation axes on the sky. Two key physical consequences then follow: first, to the extent that supernova "kicks' are responsible for pulsar proper motions, they are mostly to the rotation axis; and second that most pulsar radiation is heavily processed by the magnetospheric plasma such that the lowest altitude "parent' core emission is polarized ⊥ to the emitting field, propagating as the extraordinary (X) mode.

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“…A geometrical framework of the model was founded already by Radhakrishnan & Cooke (1969). Much later Blaskiewicz et al (1991) furnished the model with lowest order special relativity effects. However, the noncoherent high-energy emission has a different spatial origin and requires a separate study.…”

Section: Introductionmentioning

confidence: 99%

Relativistic Effects and Polarization in Three High‐Energy Pulsar Models

Dyks

Harding

Rudak

2004

ApJ

209

292

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We present the influence of the special relativistic effects of aberration and light travel time delay on pulsar high-energy lightcurves and polarization characteristics predicted by three models: the two-pole caustic model, the outer gap model, and the polar cap model. Position angle curves and degree of polarization are calculated for the models and compared with the optical data on the Crab pulsar. The relative positions of peaks in gamma-ray and radio lightcurves are discussed in detail for the models. We find that the two-pole caustic model can reproduce qualitatively the optical polarization characteristics of the Crab pulsar -fast swings of the position angle and minima in polarization degree associated with both peaks. The anticorrelation between the observed flux and the polarization degree (observed in the optical band also for B0656+14) naturally results from the caustic nature of the peaks which are produced in the model due to the superposition of radiation from many different altitudes, ie. polarized at different angles. The two-pole caustic model also provides an acceptable interpretation of the main features in the Crab's radio profile. Neither the outer gap model nor the polar cap model are able to reproduce the optical polarization data on the Crab. Although the outer gap model is very successful in reproducing the relative positions of gamma-ray and radio peaks in pulse profiles, it can reproduce the high-energy lightcurves only when photon emission from regions very close to the light cylinder is included.

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A relativistic model of pulsar polarization

Cited by 301 publications

References 0 publications

PSRs J0248+6021 and J2240+5832: young pulsars in the northern Galactic plane

PSRs J0248+6021 and J2240+5832: young pulsars in the northern Galactic plane

Toward an Empirical Theory of Pulsar Emission. Xi. Understanding the Orientations of Pulsar Radiation and Supernova “Kicks”

Relativistic Effects and Polarization in Three High‐Energy Pulsar Models

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