The Effects of Nonlinear Terms in Cosmic-Ray Diffusion Theory

Owens, A. J.

doi:10.1086/152960

Cited by 67 publications

(43 citation statements)

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“…ally, QLT has problems in treating scattering of particles with momentum nearly perpendicular to the magnetic field (see Jones et al 1973Jones et al , 1978Völk 1973Völk , 1975Owens 1974;Goldstein 1976;Felice and Kulsrud 2001) and perpendicular transport (see Kóta and Jokipii 2000;.…”

Section: Second Order Fermi Acceleration and Turbulencementioning

confidence: 99%

Turbulence, Magnetic Reconnection in Turbulent Fluids and Energetic Particle Acceleration

et al. 2012

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Turbulence is ubiquitous in astrophysics. It radically changes many astrophysical phenomena, in particular, the propagation and acceleration of cosmic rays. We present the modern understanding of compressible magnetohydrodynamic (MHD) turbulence, in particular its decomposition into Alfvén, slow and fast modes, discuss the density structure of turbulent subsonic and supersonic media, as well as other relevant regimes of astrophysical turbulence. All this information is essential for understanding the energetic par- ticle acceleration that we discuss further in the review. For instance, we show how fast and slow modes accelerate energetic particles through the second order Fermi acceleration, while density fluctuations generate magnetic fields in pre-shock regions enabling the first order Fermi acceleration of high energy cosmic rays. Very importantly, however, the first order Fermi cosmic ray acceleration is also possible in sites of magnetic reconnection. In the presence of turbulence this reconnection gets fast and we present numerical evidence supporting the predictions of the Lazarian & Vishniac (1999) model of fast reconnection. The efficiency of this process suggests that magnetic reconnection can release substantial amounts of energy in short periods of time. As the particle tracing numerical simulations show that the particles can be efficiently accelerated during the reconnection, we argue that the process of magnetic reconnection may be much more important for particle acceleration than it is currently accepted. In particular, we discuss the acceleration arising from reconnection as a possible origin of the anomalous cosmic rays measured by Voyagers as well as the origin cosmic ray excess in the direction of Heliotail.

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Section: Second Order Fermi Acceleration and Turbulencementioning

confidence: 99%

Turbulence, Magnetic Reconnection in Turbulent Fluids and Energetic Particle Acceleration

et al. 2012

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“…In the second place, developments in scattering theory subsequent to Paper II indicate that scatterir.g near ~ = 0 is not weak enough> to allow the purely coherent mode to persist (Jones, Kaiser and Birmingham 1973, Volk 1973, Owens 1974). These discrepancies do not apply to the super coherent mode, for it occurs even in the presence of scattering at II -0, and its velocity is close to the observed one.…”

Section: • the Supercoherent Modementioning

confidence: 99%

The effect of adiabatic focusing upon charged-particle propagation in random magnetic fields

Earl¹

1976

ApJ

152

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“…16 Its fundamental idea may be summarized quite simply: while in quasi-linear theory the effects of the fluctuating field are computed along a particle orbit in the ensemble averaged field, in the present approach the orbit that is used is the particle's orbit in a partially ensemble averaged field. The partially averaged field is averaged only over a subset of the full ensemble, namely the subset of all realizations in which the value of the field at a certain fixed point has a fixed value.…”

Section: The Partially Averaged Field Approach To Cosmic Ray Diffusiomentioning

confidence: 99%

Partially averaged field approach to cosmic ray diffusion

Jones

Birmingham

Kaiser

1978

The Physics of Fluids

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The kinetic equation for particles interacting with turbulent fluctuations is derived by a new nonlinear technique which successfully corrects the difficulties associated with quasi-linear theory. In this new method the effects of the fluctuations are evaluated along particle orbits which themselves include the effects of a statistically averaged subset of the possible configurations of the turbulence. The new method is illustrated by calculating the pitch angle diffusion coefficient Dμμ for particles interacting with ’’slab model’’ magnetic turbulence, i.e., magnetic fluctuations linearly polarized transverse to a mean magnetic field 〈B〉. Results are compared with those of quasi-linear theory and also with those of Monte Carlo calculations reported in a companion paper. The major effect of the nonlinear treatment in this illustration is the determination of Dμμ in the vicinity of 90° pitch angles where quasi-linear theory breaks down. The spatial diffusion coefficient κ∥ parallel to 〈B〉 is evaluated using Dμμ as calculated by our technique. It is argued that the partially averaged field method is not limited to small amplitude fluctuating fields and hence is not a perturbation theory.

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The Effects of Nonlinear Terms in Cosmic-Ray Diffusion Theory

Cited by 67 publications

References 0 publications

Turbulence, Magnetic Reconnection in Turbulent Fluids and Energetic Particle Acceleration

Turbulence, Magnetic Reconnection in Turbulent Fluids and Energetic Particle Acceleration

The effect of adiabatic focusing upon charged-particle propagation in random magnetic fields

Partially averaged field approach to cosmic ray diffusion

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