scholarly journals Nonlinear Monte Carlo model of superdiffusive shock acceleration with magnetic field amplification

2017 ◽  
Vol 95 (3) ◽  
Author(s):  
Andrei M. Bykov ◽  
Donald C. Ellison ◽  
Sergei M. Osipov
Keyword(s):  
Magnetic Field ◽  
Monte Carlo ◽  
Monte Carlo Model ◽  
Shock Acceleration ◽  
Field Amplification

scholarly journals Self-consistent Monte Carlo model of particle acceleration by relativistic shocks

2021 ◽  
Vol 2103 (1) ◽  
pp. 012014
Author(s):  
S M Osipov ◽  
A M Bykov ◽  
M Lemoine
Keyword(s):  
Magnetic Field ◽  
Monte Carlo ◽  
Particle Acceleration ◽  
Monte Carlo Model ◽  
Cosmic Ray ◽  
Field Amplification ◽  
Relativistic Shocks ◽  
Self Consistent ◽  
The Magnetic Field ◽  
Accelerated Particles

Abstract We present a self-consistent Monte Carlo model of particle acceleration by relativistic shock waves. The model includes the magnetic field amplification in the shock upstream by cosmic ray driven plasma instabilities. The parameters of the Monte Carlo model are obtained based on PIC calculations. We present the spectra of accelerated particles simulated in the frame of the model.

Circulation of energetic ions within Ganymede’s magnetosphere: a Monte-Carlo simulation approach

2021 ◽  
Author(s):  
Christina Plainaki ◽  
Stefano Massetti ◽  
Xianzhe Jia ◽  
Alessandro Mura ◽  
Anna Milillo ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Monte Carlo ◽  
Plasma Sheet ◽  
Monte Carlo Model ◽  
Weather Conditions ◽  
The Moon ◽  
Water Release ◽  
Energetic Ions ◽  
Surface Precipitation ◽  
Long Term Impact

<p>The study of Ganymede, the only known moon in the Solar System to possess an intrinsic magnetic field embedded within a planetary magnetosphere, is of significant importance in view of future missions to the Jovian system. Indeed, the dynamics of the entry and circulation inside Ganymede’s magnetosphere of the Jovian energetic ions, as well as the morphology of their precipitation on the moon’s surface determine the variability of the sputtered-water release and exosphere generation. The so-called planetary space weather conditions around Ganymede can also have a long-term impact on the weathering history of its icy surface.</p> <p>In this talk, I will discuss some key characteristics of the circulation of the Jovian magnetospheric ions within the environment of Ganymede as derived from the application of a single-particle Monte Carlo model driven by the electromagnetic fields from a global MHD model. In particular, the Jovian energetic ion circulation and precipitation to Ganymede’ s surface was estimated for different relative configurations between the moon’s magnetic field and Jupiter’s plasma sheet, characterized by conditions similar to those encountered during the NASA Galileo G2, G8, and G28 flybys of Ganymede (i.e., when the moon was above, inside, and below the center of Jupiter’ s plasma sheet). The resulting differences between the various surface precipitation patterns and the implications in the water sputtering rate will be discussed. The results of this preliminary analysis are relevant to ESA’ s JUICE mission and in particular to the planning of future observation strategies for studying Ganymede’ s environment.</p>

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 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 Gold Nanoparticle DNA Damage by Photon Beam in a Magnetic Field: A Monte Carlo Study

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1751
Author(s):  
Mehwish Jabeen ◽  
James C. L. Chow
Keyword(s):  
Magnetic Field ◽  
Dna Damage ◽  
Monte Carlo ◽  
Gold Nanoparticle ◽  
Monte Carlo Model ◽  
Photon Beam ◽  
Dose Enhancement ◽  
The Impact ◽  
The Magnetic Field ◽  
Field Strengths

Ever since the emergence of magnetic resonance (MR)-guided radiotherapy, it is important to investigate the impact of the magnetic field on the dose enhancement in deoxyribonucleic acid (DNA), when gold nanoparticles are used as radiosensitizers during radiotherapy. Gold nanoparticle-enhanced radiotherapy is known to enhance the dose deposition in the DNA, resulting in a double-strand break. In this study, the effects of the magnetic field on the dose enhancement factor (DER) for varying gold nanoparticle sizes, photon beam energies and magnetic field strengths and orientations were investigated using Geant4-DNA Monte Carlo simulations. Using a Monte Carlo model including a single gold nanoparticle with a photon beam source and DNA molecule on the left and right, it is demonstrated that as the gold nanoparticle size increased, the DER increased. However, as the photon beam energy decreased, an increase in the DER was detected. When a magnetic field was added to the simulation model, the DER was found to increase by 2.5–5% as different field strengths (0–2 T) and orientations (x-, y- and z-axis) were used for a 100 nm gold nanoparticle using a 50 keV photon beam. The DNA damage reflected by the DER increased slightly with the presence of the magnetic field. However, variations in the magnetic field strength and orientation did not change the DER significantly.

scholarly journals New high-frequency radio observations of the Cygnus Loop supernova remnant with the Italian radio telescopes

2020 ◽  
Vol 500 (4) ◽  
pp. 5177-5194
Author(s):  
S Loru ◽  
A Pellizzoni ◽  
E Egron ◽  
A Ingallinera ◽  
G Morlino ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Frequency ◽  
Supernova Remnants ◽  
Cosmic Ray ◽  
Maximum Energy ◽  
Shock Acceleration ◽  
Radio Telescopes ◽  
Spectral Parameters ◽  
Cygnus Loop ◽  
Field Amplification

ABSTRACT Supernova remnants (SNRs) represent a powerful laboratory to study the cosmic ray acceleration processes at shocks, and their relation to the properties of the circumstellar medium. With the aim of studying the high-frequency radio emission and investigating the energy distribution of accelerated electrons and the magnetic field conditions, we performed single-dish observations of the large and complex Cygnus Loop SNR from 7.0–24.8 GHz with the Medicina and Sardinia Radio Telescopes, focusing on the northern filament (NGC 6992) and the southern shell. Both regions show a spectrum well fitted by a power-law function (S ∝ ν−α), with spectral index α = 0.45 ± 0.05 for NGC 6992 and α = 0.49 ± 0.01 for the southern shell and without any indication of a spectral break. The spectra are significantly flatter than the whole Cygnus Loop spectrum (α = 0.54 ± 0.01), suggesting a departure from the plain shock acceleration mechanisms, which for NGC 6992 could be related to the ongoing transition towards a radiative shock. We model the integrated spectrum of the whole SNR considering the evolution of the maximum energy and magnetic field amplification. Through the radio spectral parameters, we infer a magnetic field at the shock of 10 μG. This value is compatible with purely adiabatic compression of the interstellar magnetic field, suggesting that the amplification process is currently inefficient.

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