WAVE TRANSMISSION AND HARD PARTICLE SPECTRA FROM PARALLEL SHOCKS

I review recent results concerning the effects that relativistic parallel shocks can have on the particle-scattering turbulence, and how these effects, in turn, can change the shock's particle acceleration properties. I discuss the possibility of increased compression ratio due to this kind of turbulence transmission, and consider the effects of additional compression on the energy spectrum of the accelerated particles. Emphasis is put on the possibility of producing spectral indices that are significantly harder than what is usually expected from the first-order Fermi mechanism, but required by some observations. Finally, I discuss the physical requirements — and their plausibility in real astronomical objects — of this mechanism to have notable effects.

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Spectrum and polarization of radio galaxy lobes and tails

Canadian Journal of Physics ◽

10.1139/p86-067 ◽

1986 ◽

Vol 64 (4) ◽

pp. 381-382 ◽

Cited By ~ 1

Author(s):

Heinz Andernach

Keyword(s):

Particle Acceleration ◽

Energy Spectrum ◽

Faraday Rotation ◽

Radio Galaxy ◽

Radio Galaxies ◽

Ambient Media ◽

Antenna Beam ◽

Accelerated Particles

The distribution of radio spectra across six radio galaxies is studied at ~4′ resolution. Spectral breaks consistent with the absence of particle acceleration are rare, and spectra do not always show the expected steepening with core distance or with frequency. Even in far outer tails there is evidence for recent reacceleration. Spectral flattening often occurs near bends, wiggles, and knots; thus, particle acceleration seems most efficient at "working surfaces" with the ambient media. Radio spectra indicate an energy spectrum of the accelerated particles flatter than ~E−1.6 in these areas. Some polarization maps reveal inverted depolarization and departures from the λ2 law of Faraday rotation, probably due to different physical regimes within one antenna beam.

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Nucleosynthesis by accelerated particles in a bipolar Supernova explosion

HNPS Proceedings ◽

10.12681/hnps.2582 ◽

2020 ◽

Vol 16 ◽

pp. 67

Author(s):

G. Vernardos ◽

S. Goriely ◽

G. Lalazissis

Keyword(s):

Energy Spectrum ◽

Supernova Explosion ◽

Model Parameters ◽

Spherically Symmetric ◽

Final Phase ◽

Abundance Pattern ◽

Stellar Matter ◽

Accelerated Particles

The most spectacular final phase of an evolved star, is the supernova explosion. It has been suggested by observations that such an event might not be spherically symmetric. This asphericity could be explained by the formation of jets of accel- erated particles by the explosion, which could interact with the stellar matter and give rise to a possible nucleosynthesis. Such a nucleosynthesis is studied. The fi- nal abundance pattern is shown to depend on the values of the model parameters adopted, especially the energy spectrum of the accelerated particles.

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The Spectrum of Steady State Turbulent Convection

Zeitschrift für Naturforschung A ◽

10.1515/zna-1971-0708 ◽

1971 ◽

Vol 26 (7) ◽

pp. 1140-1146

Author(s):

F. Winterberg

Keyword(s):

Integral Equation ◽

Steady State ◽

Energy Spectrum ◽

Buoyancy Force ◽

Radiative Heat ◽

Order Differential Equation ◽

Stellar Atmospheres ◽

Turbulent Convection ◽

First Order ◽

Model Equations

Abstract Based on Heisenberg's statistical theory of turbulence, a model for steady state turbulent convection is herein proposed, and on the basis of this model, equations for the energy spectrum for steady state turbulent convection are derived. The spectrum is obtained from the solution of a nonlinear integral equation. After the integral equation is brought into a universally valid nondimensional form, it is transformed into a nonlinear first order differential equation to be solved numerically, with the Rayleigh number appearing as the only parameter. The energy spectrum has a substantial deviation from the Kolmogoroff law, as a result of the buoyancy force acting on the rising and falling eddies. The presented theory may be applicable to convection in planetary and stellar atmospheres wherein the radiative heat transport is small.

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Nonlinear dynamics of soft fermion excitations in hot QCD plasma II: Soft-quark–hard-particle scattering and energy losses

Nuclear Physics A ◽

10.1016/j.nuclphysa.2006.12.001 ◽

2007 ◽

Vol 784 (1-4) ◽

pp. 443-514 ◽

Cited By ~ 11

Author(s):

Yu.A. Markov ◽

M.A. Markova

Keyword(s):

Nonlinear Dynamics ◽

Energy Losses ◽

Hard Particle ◽

Particle Scattering

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PARTITION FUNCTIONS OF THE SUPERCONFORMAL GHOST THIRRING MODEL

International Journal of Modern Physics A ◽

10.1142/s0217751x89002387 ◽

1989 ◽

Vol 04 (20) ◽

pp. 5553-5574 ◽

Cited By ~ 6

Author(s):

D. Z. FREEDMAN ◽

K. PILCH

Keyword(s):

Energy Spectrum ◽

Path Integral ◽

Formal Series ◽

Open String ◽

Integral Representations ◽

Thirring Model ◽

Partition Functions ◽

First Order ◽

Integral Methods ◽

The One

The one-loop partition functions of the superconformal Thirring model for first order b − c and β − γ ghost fields are studied for both closed and open string boundary conditions. Bosonized partition functions are given by formal series which usually diverge because the energy spectrum of the theory is unbounded below as a correlate of nonunitarity. However, the same partition functions are then calculated by path integral methods directly in the fermionic formulation, and well-defined (convergent) integral representations are obtained. A formal series expansion of those integrals reproduces the bosonized partition functions.

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RELATIVISTIC SHOCK ACCELERATION AND SOME CONSEQUENCES

International Journal of Modern Physics Conference Series ◽

10.1142/s2010194514601665 ◽

2014 ◽

Vol 28 ◽

pp. 1460166 ◽

Cited By ~ 1

Author(s):

MARTIN LEMOINE ◽

GUY PELLETIER

Keyword(s):

Particle Acceleration ◽

Gamma Ray ◽

Light Curves ◽

Shock Acceleration ◽

Theoretical Understanding ◽

Relativistic Shock ◽

Multi Wavelength ◽

The Impact ◽

Wavelength Light ◽

Accelerated Particles

This paper summarizes recent progresses in our theoretical understanding of particle acceleration at relativistic shock waves and it discusses two salient consequences: (1) the maximal energy of accelerated particles; (2) the impact of the shock-generated micro-turbulence on the multi-wavelength light curves of gamma-ray burst afterglows.

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Balance dynamics in rotating stratified turbulence

Journal of Fluid Mechanics ◽

10.1017/jfm.2016.164 ◽

2016 ◽

Vol 795 ◽

pp. 914-949 ◽

Cited By ~ 21

Author(s):

Hossein A. Kafiabad ◽

Peter Bartello

Keyword(s):

Energy Spectrum ◽

Rossby Number ◽

Stratified Turbulence ◽

Nonlinear Normal Mode ◽

Initial Flow ◽

First Order ◽

Initialization Scheme ◽

Nonlinear Normal ◽

Balance Dynamics ◽

Normal Mode Initialization

If classical quasigeostrophic (QG) flow breaks down at smaller scales, it gives rise to questions of whether higher-order nonlinear balance can be maintained, to what scale and for how long. These are naturally followed by asking how this is affected by stratification and rotation. To address these questions, we perform non-hydrostatic Boussinesq simulations where the initial data is balanced using the Baer–Tribbia nonlinear normal mode initialization scheme (NNMI), which is accurate to second order in the Rossby number, as the next-order improvement to first-order QG theory. The NNMI procedure yields an ageostrophic contribution to the energy spectrum that has a very steep slope. However, as time passes, a shallow range emerges in the ageostrophic spectrum when the Rossby number is large enough for a given Reynolds number. It is argued that this shallow range is the unbalanced part of the motion that develops spontaneously in time and eventually dominates the energy at small scales. If the initial flow is not nonlinearly balanced, the shallow range emerges at even lower Rossby number and it appears at larger scales. Through numerous simulations at different rotation and stratification, this study gives a clear picture of how energy is cascaded in different initially balanced regimes of rotating stratified flow. We find that at low Rossby number the flow mainly consists of a geostrophic part and a balanced ageostrophic part with a steep spectrum. As the Rossby number increases, the unbalanced part of the ageostrophic energy increases at a rate faster than the balanced part. Hence, the total energy spectrum displays a shallow range above a transition wavenumber. This wavenumber evolves to smaller values as rotation weakens.

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Particle Acceleration by Waves and Fields

Highlights of Astronomy ◽

10.1017/s1539299600018967 ◽

1998 ◽

Vol 11 (2) ◽

pp. 865-868

Author(s):

Wolfgang Dröge

Keyword(s):

Particle Acceleration ◽

Gamma Ray ◽

Interplanetary Space ◽

Particle Accelerators ◽

Particle Detectors ◽

The Galaxy ◽

Electromagnetic Emissions ◽

Particle Spectra ◽

The Universe

The acceleration of electrons and charged nuclei to high energies is a phenomenon occuring at many sites throughout the universe, including the galaxy, pulsars, quasars, and around black holes. In the heliosphere, large solar flares and the often associated coronal mass ejections (CMEs) are the most energetic natural particle accelerators, occasionally accelerating protons to GeV and electrons to tens of MeV energies. The observation of these particles offers the unique opportunity to study fundamental processes in astrophysics. Particles that escape into interplanetary space can be observed in situ with particle detectors on spacecraft. In particular, particle spectra can be diagnostic of flare acceleration processes. On the other hand, energetic processes on the sun can be studied indirectly, via observations of the electromagnetic emissions (radio, X-ray, gamma-ray) produced by the particles in their interactions with the solar atmosphere. The purpose of this article is to give a brief overview on current models on particle acceleration and the present status of observations of solar energetic particles.

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