Diffusive shock acceleration in the presence of a strong ambient magnetic field

1990 ◽  
Vol 348 ◽  
pp. 221 ◽  
Author(s):  
Abhas Mitra
Keyword(s):  
Magnetic Field ◽  
Shock Acceleration ◽  
Diffusive Shock Acceleration ◽  
Ambient Magnetic Field

scholarly journals Cosmic rays and stochastic magnetic reconnection in the heliotail

2012 ◽  
Vol 19 (3) ◽  
pp. 351-364 ◽  
Author(s):  
P. Desiati ◽  
A. Lazarian
Keyword(s):  
Magnetic Field ◽  
Cosmic Rays ◽  
Magnetic Reconnection ◽  
Supernova Remnants ◽  
Average Energy ◽  
Cosmic Ray ◽  
Galactic Cosmic Rays ◽  
Shock Acceleration ◽  
Diffusive Shock Acceleration ◽  
The Galaxy

Abstract. Galactic cosmic rays are believed to be generated by diffusive shock acceleration processes in Supernova Remnants, and the arrival direction is likely determined by the distribution of their sources throughout the Galaxy, in particular by the nearest and youngest ones. Transport to Earth through the interstellar medium is expected to affect the cosmic ray properties as well. However, the observed anisotropy of TeV cosmic rays and its energy dependence cannot be explained with diffusion models of particle propagation in the Galaxy. Within a distance of a few parsec, diffusion regime is not valid and particles with energy below about 100 TeV must be influenced by the heliosphere and its elongated tail. The observation of a highly significant localized excess region of cosmic rays from the apparent direction of the downstream interstellar flow at 1–10 TeV energies might provide the first experimental evidence that the heliotail can affect the transport of energetic particles. In particular, TeV cosmic rays propagating through the heliotail interact with the 100–300 AU wide magnetic field polarity domains generated by the 11 yr cycles. Since the strength of non-linear convective processes is expected to be larger than viscous damping, the plasma in the heliotail is turbulent. Where magnetic field domains converge on each other due to solar wind gradient, stochastic magnetic reconnection likely occurs. Such processes may be efficient enough to re-accelerate a fraction of TeV particles as long as scattering processes are not strong. Therefore, the fractional excess of TeV cosmic rays from the narrow region toward the heliotail direction traces sightlines with the lowest smearing scattering effects, that can also explain the observation of a harder than average energy spectrum.

scholarly journals Nonlinear Diffusive Shock Acceleration with Magnetic Field Amplification

2006 ◽  
Vol 652 (2) ◽  
pp. 1246-1258 ◽  
Author(s):  
Andrey Vladimirov ◽  
Donald C. Ellison ◽  
Andrei Bykov
Keyword(s):  
Magnetic Field ◽  
Shock Acceleration ◽  
Diffusive Shock Acceleration ◽  
Field Amplification

scholarly journals Oblique Shocks in Extragalactic Jets

1990 ◽  
Vol 140 ◽  
pp. 437-437
Author(s):  
D. Fraix-Burnet
Keyword(s):  
Magnetic Field ◽  
High Resolution ◽  
Shock Front ◽  
Shock Acceleration ◽  
Relativistic Electrons ◽  
Optical Polarization ◽  
Diffusive Shock Acceleration ◽  
Extragalactic Jets ◽  
The Magnetic Field ◽  
Oblique Shocks

In the framework of the diffusive shock acceleration of relativistic electrons in extragalactic jets, we show that it is possible to derive the speed of the jet. For this purpose, we transform continuity relations through an oblique shock front into the reference frame of the observer. We apply these calculations to knot A of the M87 jet. Measuring the deviation of the fluid through the shock front from high-resolution radio maps and the deviation of the magnetic field from optical polarization maps (Fraix-Burnet et al., 1989), we derive speeds of about 0.01 c (Fraix-Burnet and Biermann, in preparation). The compression ratio is most probably 4 and the magnetic field is nearly parallel to the shock front both upstream and downstream.

scholarly journals Interaction of Jets with Clouds in Extragalactic Radio Sources

1994 ◽  
Vol 159 ◽  
pp. 346-346
Author(s):  
V. Fedorenko ◽  
A. Zentsova ◽  
T. J.-L. Courvoisier ◽  
S. Paltani
Keyword(s):  
Magnetic Field ◽  
Supernova Remnants ◽  
Shock Acceleration ◽  
Stellar Winds ◽  
Radio Sources ◽  
Red Giants ◽  
Diffusive Shock Acceleration ◽  
Extragalactic Jets ◽  
The Magnetic Field ◽  
Very High

Several points indicate that extragalactic jets can interact with dense gaseous obstacles which occur on their ways. Examples of these interactions are the knotty structure of the radio and optical jet in M 87 and in other objects. These observations have been interpreted by Blandford & Königl in terms of collision of a jet with supernova remnants. We have reanalysed this idea taking into account new observations and improvements in the theory of diffusive shock acceleration. We find that the model requires a very high supernova birthrate (∼ 1 SN/year), which is not observed. It is more probable that the “obstacles” are formed by the stellar winds from the red giants. We estimate that the value of the magnetic field is ∼ 10−5 G in the interaction region (r=1kpc) (paper in preparation).

scholarly journals On the Role of Magnetic Field Fluctuations in Diffusive Shock Acceleration

2011 ◽  
Vol 21 (3) ◽  
pp. 199
Author(s):  
Doan Kim The ◽  
Pham Tuan Anh ◽  
Pham Ngoc Diep ◽  
Pham Ngoc Dong ◽  
Nguyen Van Hiep ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Uniform Magnetic Field ◽  
Field Component ◽  
Larmor Radius ◽  
Shock Acceleration ◽  
Simultaneous Presence ◽  
Diffusive Shock Acceleration ◽  
Cosmic Particle ◽  
Field Fluctuations

A simple numerical simulation of the mechanism of diffusive shock acceleration, responsible for the acceleration of cosmic rays in the environment of young Super Nova Remnants, is presented. The relative roles of a uniform magnetic field component, inherited from the parent collapsed star, and of magnetic turbulences, known to be present in the vicinity of the shock, are investigated. It is shown that a uniform magnetic field allows for only doubling the energy of the cosmic particle. Important accelerations require the simultaneous presence of magnetic field turbulences at a scale commensurable with its Larmor radius.

scholarly journals Particle acceleration and magnetic field amplification in massive young stellar object jets

2021 ◽  
Author(s):  
Anabella T Araudo ◽  
Marco Padovani ◽  
Alexandre Marcowith
Keyword(s):  
Magnetic Field ◽  
Cosmic Ray ◽  
Maximum Energy ◽  
Shock Acceleration ◽  
Relativistic Electrons ◽  
Diffusive Shock Acceleration ◽  
Field Amplification ◽  
Protostellar Jets ◽  
Γ Rays ◽  
The Magnetic Field

Abstract Synchrotron radio emission from non-relativistic jets powered by massive protostars has been reported, indicating the presence of relativistic electrons and magnetic fields of strength ∼0.3 −5 mG. We study diffusive shock acceleration and magnetic field amplification in protostellar jets with speeds between 300 and 1500 km s−1. We show that the magnetic field in the synchrotron emitter can be amplified by the non-resonant hybrid (Bell) instability excited by the cosmic-ray streaming. By combining the synchrotron data with basic theory of Bell instability we estimate the magnetic field in the synchrotron emitter and the maximum energy of protons. Protons can achieve maximum energies in the range 0.04 − 0.65 TeV and emit γ rays in their interaction with matter fields. We predict detectable levels of γ rays in IRAS 16547-5247 and IRAS 16848-4603. The γ ray flux can be significantly enhanced by the gas mixing due to Rayleigh-Taylor instability. The detection of this radiation by the Fermi satellite in the GeV domain and the forthcoming Cherenkov Telescope Array at higher energies may open a new window to study the formation of massive stars, as well as diffusive acceleration and magnetic field amplification in shocks with velocities of about 1000 km s−1.

scholarly journals Diagnosing particle acceleration in relativistic jets

2014 ◽  
Vol 10 (S313) ◽  
pp. 153-158
Author(s):  
Markus Böttcher ◽  
Matthew G. Baring ◽  
Edison P. Liang ◽  
Errol J. Summerlin ◽  
Wen Fu ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Particle Acceleration ◽  
Lorentz Factor ◽  
High Energy ◽  
Shock Acceleration ◽  
Relativistic Jets ◽  
Diffusive Shock Acceleration ◽  
Magnetic Field Generation ◽  
Particle Distributions ◽  
Particle In Cell

AbstractThe high-energy emission from blazars and other relativistic jet sources indicates that electrons are accelerated to ultra-relativistic (GeV - TeV) energies in these systems. This paper summarizes recent results from numerical studies of two fundamentally different particle acceleration mechanisms potentially at work in relativistic jets: Magnetic-field generation and relativistic particle acceleration in relativistic shear layers, which are likely to be present in relativistic jets, is studied via Particle-in-Cell (PIC) simulations. Diffusive shock acceleration at relativistic shocks is investigated using Monte-Carlo simulations. The resulting magnetic-field configurations and thermal + non-thermal particle distributions are then used to predict multi-wavelength radiative (synchrotron + Compton) signatures of both acceleration scenarios. In particular, we address how anisotropic shear-layer acceleration may be able to circumvent the well-known Lorentz-factor crisis, and how the self-consistent evaluation of thermal + non-thermal particle populations in diffusive shock acceleration simulations provides tests of the bulk Comptonization model for the Big Blue Bump observed in the SEDs of several blazars.

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