Particle Acceleration at Quasi-Parallel Shock Waves: Theory and Observations at 1 Au

Parker, Linda Neergaard; Zank, G. P.

doi:10.1088/0004-637x/757/1/97

Cited by 29 publications

(10 citation statements)

References 39 publications

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“…The observational results affirm particle acceleration at the shock as the acceleration mechanism. Suprathermal particles from the background solar wind were found to be efficiently injected into the DSA mechanism, in agreement with Neergaard−Parker and Zank (2012) [40]. Giacalone concluded that: "...…”

Section: Association Of Gradual Sep Events With Shock Wavessupporting

confidence: 74%

“…This mechanism creates a plateau in the energetic particle flux observed during the passage of a shock past an observer. [40] and Giacalone (2012) [41]. Figure 3 illustrates the hypothesis of Tylka et al The study [13] also emphasizes that shock geometry evolves (from quasi-perpendicular to quasi-parallel) as the shock propagates from the Sun, thus introducing different seed populations at different radial distances.…”

Section: Composition Of the Pre-accelerated Particlesmentioning

confidence: 80%

“…Neergaard−Parker and Zank (2012) [40] find that particles with energies ≥1 keV from the solar wind background Maxwellian distribution can be accelerated by the DSA mechanism and provide the right number density of particles as observed in the downstream energetic particle distribution.…”

Section: Composition Of the Pre-accelerated Particlesmentioning

confidence: 99%

See 2 more Smart Citations

A theoretical perspective on particle acceleration by interplanetary shocks and the Solar Energetic Particle problem

Verkhoglyadova

Zank

2015

Physics Reports

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Section: Association Of Gradual Sep Events With Shock Wavessupporting

confidence: 74%

Section: Composition Of the Pre-accelerated Particlesmentioning

confidence: 80%

See 1 more Smart Citation

A theoretical perspective on particle acceleration by interplanetary shocks and the Solar Energetic Particle problem

Verkhoglyadova

Zank

2015

Physics Reports

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“…p max is the maximum particle momentum (energy) to which a particle may be accelerated and depends on individual shock characteristics, background magnetic field, and the amplitude of the turbulence. The upstream particle distribution can have two components, the background upstream injection distribution ϕ(p), sometimes modeled as a Maxwellian or kappa distribution (Neergaard Parker & Zank 2012;Neergaard Parker et al 2014), or a mono-energetic delta function injected at the shock itself (Melrose & Pope 1993;Reames 2012) as a possible seed population, ψ(p). Therefore, the total upstream distribution then is…”

Section: Overviewmentioning

confidence: 99%

Particle Energization During Solar Maximum: Diffusive Shock Acceleration at Multiple Shocks

Parker

Zank

2014

ApJ

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We present a model for the acceleration of particles at multiple shocks using an approach related to box models. A distribution of particles is diffusively accelerated inside the box while simultaneously experiencing decompression through adiabatic expansion and losses from the convection and diffusion of particles out of the box by either the method used in Melrose & Pope and Pope & Melrose or by the approach introduced in Zank et al. where we solve the transport equation by a method analogous to operator splitting. The second method incorporates the additional loss terms of convection and diffusion and allows for the use of a variable time between shocks. We use a maximum injection energy (E max ) appropriate for quasi-parallel and quasi-perpendicular shocks. We provide a preliminary application of the diffusive acceleration of particles by multiple shocks with frequencies appropriate for solar maximum.

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“…For example, the electron distributions measured in the IPM can be fitted with the κdistributions with κ e ∼ 2 − 5, while the proton distributions prefer a somewhat larger κ p (Pierrard & Lazar 2010). Us-ing in situ spacecraft data, Neergaard-Parker & Zank (2012) suggested that the proton spectra observed downstream of quasi-parallel interplanetary shocks can be explained by the injection from the upstream (solar-wind) thermal Maxwellian or weak κ-distribution with κ p 10. On the other hand, Neergaard-Parker et al (2014) showed that the upstream suprathermal tail of the κ p = 4 distribution is the best to fit the proton spectra observed downstream of quasi-perpendicular interplanetary shocks 1 .…”

Section: Introductionmentioning

confidence: 99%

INJECTION OF Κ-Like SUPRATHERMAL PARTICLES INTO DIFFUSIVE SHOCK ACCELERATION

Kang

Petrosian

Ryu

et al. 2014

ApJ

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We consider a phenomenological model for the thermal leakage injection in the diffusive shock acceleration (DSA) process, in which suprathermal protons and electrons near the shock transition zone are assumed to have the so-called κ-distributions produced by interactions of background thermal particles with pre-existing and/or self-excited plasma/MHD waves or turbulence. The κ-distribution has a power-law tail, instead of an exponential cutoff, well above the thermal peak momentum. So there are a larger number of potential seed particles with momentum, above that required for participation in the DSA process. As a result, the injection fraction for the κ-distribution depends on the shock Mach number much less severely compared to that for the Maxwellian distribution. Thus, the existence of κ-like suprathermal tails at shocks would ease the problem of extremely low injection fractions, especially for electrons and especially at weak shocks such as those found in the intracluster medium. We suggest that the injection fraction for protons ranges 10 −4 −10 −3 for a κ-distribution with 10 κ p 30 at quasi-parallel shocks, while the injection fraction for electrons becomes 10 −6 − 10 −5 for a κ-distribution with κ e 2 at quasi-perpendicular shocks. For such κ values the ratio of cosmic ray electrons to protons naturally becomes K e/p ∼ 10 −3 − 10 −2 , which is required to explain the observed ratio for Galactic cosmic rays.

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Particle Acceleration at Quasi-Parallel Shock Waves: Theory and Observations at 1 Au

Cited by 29 publications

References 39 publications

A theoretical perspective on particle acceleration by interplanetary shocks and the Solar Energetic Particle problem

A theoretical perspective on particle acceleration by interplanetary shocks and the Solar Energetic Particle problem

Particle Energization During Solar Maximum: Diffusive Shock Acceleration at Multiple Shocks

INJECTION OF Κ-Like SUPRATHERMAL PARTICLES INTO DIFFUSIVE SHOCK ACCELERATION

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