The Origin of the Magnetic Field and Relativistic Particles in the Crab Nebula

Rees, M. J.; Gunn, J. E.

doi:10.1093/mnras/167.1.1

Cited by 575 publications

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“…The shock thickness is several ion Larmor radii, and extends out to the inner edge of the X-ray torus, by which radius the coherent ion gyrations have fully dissipated. Equally interestingly, the pulsar must have accelerated the ions (and the wind) through most of the total electric potential available on open field lines & 0 pen-In accord conclusions reached by Rees & Gunn (1974), Kennel & Coroniti (1984a,b) and others, our hybrid kinetic theory of the wisps shows that by the time the wind decelerates at its termination shock, its energy density is plasma, dominated (a <C 1).…”

Section: Wisp Structure and Wind Propertiessupporting

confidence: 79%

“…Since these variable features fall right in the region which might be the particle acceleration zone, understanding what they are telling us might be a promising path to unraveling the physics of how this compact object energizes its surroundings. Rees & Gunn (1974) used simple dynamic pressure balance to suggest this very region is the place where the pulsar's outflow terminates. So long as the pulsar loses energy in relativistic form, and the relativistic energy flow cannot freely penetrate the relativistic particles and fields already in the Nebula, the dynamic pressure Eji/A£lr 2 c of the pulsar's energy loss, presumed to flow out in a solid angle Af2 < 4TT, balances the static pressure of the relativistic particles and fields in the Nebula at the radius r s « 0.2 parsecs, right in the middle of the wisp zone!…”

Section: Observations and Modelsmentioning

confidence: 99%

“…Applying Rees & Gunn's (1974) dynamic pressure balance argument to the torus geometry of (and assuming essentially all of the pulsar's rotational energy loss is carried by this "equatorial" wind) yields a termination shock radius r s « 0.2 pc. However, because 2nr s /cP ~ 10 9 , the magnetic field in the wind is almost precisely transverse, ruling out conventional diffusive Fermi acceleration in shocks as the mechanism for converting flow energy to the injection distribution of high energy pairs.…”

Section: Observations and Modelsmentioning

confidence: 99%

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Pulsar Winds

Arons

1996

International Astronomical Union Colloquium

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Abstract. The shock excitation of pulsar powered nebulae (plerions) is discussed, based on recent theoretical work on the structure of relativistic, collisionless magnetosonic shock waves. This theory is used to outline a model in which the j~2 injection spectrum of the Crab Nebula is satisfactorily accounted for. The same theory suggests a model of the "wisp" features in the Crab Nebula which accounts for these time variable features in the surface bightness as compressions associated with the magnetic overshoots within the shock structure. It is pointed out that this theory suggests observable variability in the high energy gamma rays from the Crab Nebula (e > 50 MeV).

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Section: Wisp Structure and Wind Propertiessupporting

confidence: 79%

Section: Observations and Modelsmentioning

confidence: 99%

Section: Observations and Modelsmentioning

confidence: 99%

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Pulsar Winds

Arons

1996

International Astronomical Union Colloquium

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“…a requirement first noticed by Rees & Gunn (1974) in their mixed wind-vacuum wave model. Here B x is the upstream magnetic field, A f 1 is the upstream density, and 7, is the Lorentz factor of the flow.…”

Section: Introductionmentioning

confidence: 84%

“…From momentum conservation, one expects the shock to occur roughly 10 175 cm from the pulsar (Rees & Gunn 1974). Optical observations, schematically illustrated in Figure 5, reveal the presence of the curious "wisps" in the surface brightness in this region, a series of enhancements in the surface brightness elongated in the direction perpendicular to the flow lying to the northwest of the pulsar; there is also a fainter wisp to the southeast (Scargle 1969;van den Bergh & Pritchet 1989).…”

Section: The Wisps In the Crab Nebula As Resolved Shock Structurementioning

confidence: 99%

Relativistic Particle Acceleration in Plerions

Arons

Tavani

1994

International Astronomical Union Colloquium

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We discuss recent research on the structure and particle acceleration properties of relativistic shock waves in which the magnetic field is transverse to the flow direction in the upstream medium, and whose composition is either pure electrons and positrons or primarily electrons and positrons with an admixture of heavy ions. Particlein-cell simulation techniques as well as analytic theory have been used to show that such shocks in pure pair plasmas are fully thermalized-the downstream particle spectra are relativistic Maxwellians at the temperature expected from the jump conditions. On the other hand, shocks containing heavy ions which are a minority constituent by number but which carry most of the energy density in the upstream medium do put ~20% of the flow energy into a nonthermal population of pairs downstream, whose distribution in energy space is N(E) oc E~2, where N(E)dE is the number of particles with energy between E and E + dE.The mechanism of thermalization and particle acceleration is found to be synchrotron maser activity in the shock front, stimulated by the quasi-coherent gyration of the whole particle population as the plasma flowing into the shock reflects from the magnetic field in the shock front. The synchrotron maser modes radiated by the heavy ions are absorbed by the pairs at their (relativistic) cyclotron frequencies, allowing the maximum energy achievable by the pairs to be 7+ m ± c 2 = m, c 2 7, /Z,, where y t is the Lorentz factor of the upstream flow and Z, is the atomic number of the ions. The shock's spatial structure is shown to contain a series of "overshoots" in the magnetic field, regions where the gyrating heavy ions compress the magnetic field to levels in excess of the eventual downstream value.This shock model is applied to an interpretation of the structure of the inner regions of the Crab Nebula, in particular to the "wisps," surface brightness enhancements near the pulsar. We argue that these surface brightness enhancements are the regions of magnetic overshoot, which appear brighter because the small Larmor radius pairs are compressed and radiate more efficiently in the regions of more intense magnetic field. This interpretation suggests that the structure of the shock terminating the pulsar's wind in the Crab Nebula is spatially resolved, and allows one to measure 7, and a number of other properties of the pulsar's wind. We also discuss applications of the shock theory to the termination shocks of the winds from rotation-powered pulsars embedded in compact binaries. We show that this model adequately accounts for (and indeed predicted) the recently discovered X-ray flux from PSR 1957+20, and we discuss several other applications to other examples of these systems.

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Inverse Compton origin of pulsar γ ‐ray emission and the reconnection model of Crab Nebula flares

Lyutikov¹

2014

Astron Nachr

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The Origin of the Magnetic Field and Relativistic Particles in the Crab Nebula

Cited by 575 publications

References 0 publications

Pulsar Winds

Pulsar Winds

Relativistic Particle Acceleration in Plerions

Inverse Compton origin of pulsar γ ‐ray emission and the reconnection model of Crab Nebula flares

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