A deeply embedded companion to LKH?198

Lagage, Pierre-Olivier; Olofsson, G.; Cabrit, S.; Césarsky, C. J.; Nordh, L.; Espinosa, J. M. Rodríguez

doi:10.1007/bf00430149

Cited by 106 publications

(151 citation statements)

References 1 publication

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“…One can see that the experimental data is in a good agreement with the MC prediction, and 1 We compared the results from various number of hidden nodes and found the results are not changed when we use the number of hidden nodes greater than 20. 2 The training curve becomes stable at number of training cycles 500. that the proton-induced events are clearly separated from other nuclei. 3 We define a critical value of T to separate protons from others requiring the high purity, which reduces the effect of the contamination, and the high selection efficiency of the proton events, which reduces the statistical error.…”

Section: Discussionmentioning

confidence: 99%

Are protons still dominant at the knee of the cosmic-ray energy spectrum?

et al. 2006

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Section: Discussionmentioning

confidence: 99%

Are protons still dominant at the knee of the cosmic-ray energy spectrum?

et al. 2006

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“…32 The supershells have been observed as expanding shells, or holes, in the HIcolumn density distribution of our galaxy. 33 The dimensions of these objects span from 100 pc to 1700 pc and often present elliptical shapes or elongated features, that can be explained as an expansion in a nonhomogeneous medium.…”

Section: Maximum Available Energiesmentioning

confidence: 81%

Models of Diffusion of Galactic Cosmic Rays From Superbubbles

Zaninetti¹

2007

Int. J. Mod. Phys. A

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Superbubbles are shells in the interstellar medium produced by the simultaneous explosions of many supernova remnants. The solutions of the mathematical diffusion and of the Fourier expansion in 1D, 2D and 3D were deduced in order to describe the diffusion of nucleons from such structures. The mean number of visits in the the case of the Levy flights in 1D was computed with a Monte Carlo simulation. The diffusion of cosmic rays has its physical explanation in the relativistic Larmor gyro-radius which is energy dependent. The mathematical solution of the diffusion equation in 1D with variable diffusion coefficient was computed. Variable diffusion coefficient means magnetic field variable with the altitude from the Galactic plane. The analytical solutions allow us to calibrate the code that describes the Monte Carlo diffusion. The maximum energy that can be extracted from the superbubbles is deduced. The concentration of cosmic rays is a function of the distance from the nearest superbubble and the selected energy. The interaction of the cosmic rays on the target material allows us to trace the theoretical map of the diffuse Galactic continuum gamma-rays. The streaming of the cosmic rays from the Gould Belts that contains the sun at its internal was described by a Monte Carlo simulation. Ten new formulas are derived.

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“…A well known estimate of the maximal acceleration energy for non-relativistic shocks compares the acceleration timescale, t acc ∼ t scatt /β 2 sh (with t scatt ∼ D/c 2 the diffusion timescale in the shock environment) to the age of the shock wave R/(β sh c) to infer (Lagage & Césarsky 1983, Hillas 1984): E max ∼ β sh eRB if Bohm diffusion applies in the magnetic field B, meaning t scatt ∼ t L . This estimate suggests that relativistic shock waves with β sh → 1 appear as efficient particle accelerators to ultra-high energy.…”

Section: Acceleration To Ultra-high Energiesmentioning

confidence: 99%

Particle acceleration at relativistic shock waves

Lemoine¹,

Pelletier²

2017

AIP Conference Proceedings

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Abstract. Relativistic sources, e.g. gamma-ray bursts, pulsar wind nebulae and powerful active galactic nuclei produce relativistic outflows that lead to the formation of collisionless shock waves, where particle acceleration is thought to take place. Our understanding of relativistic shock acceleration has improved in the past decade, thanks to the combination of analytical studies and high level numerical simulations. In ultra-relativistic shocks, particle acceleration is made difficult by the generically transverse magnetic field and large advection speed of the shocked plasma. Fast growing microturbulence is thus needed to make the Fermi process operative. It is thought, and numerical simulations support that view, that the penetration of supra-thermal particles in the shock precursor generates a magnetic turbulence which in turn produces the scattering process needed for particle acceleration through the Fermi mechanism. Through the comparison of the growth timescale of the microinstabilities in the shock precursor and the precursor crossing timescale, it is possible to delimit in terms of magnetization and shock Lorentz factor the region in which micro-turbulence may be excited, hence whether and how Fermi acceleration is triggered. These findings are summarized here and astrophysical consequences are drawn.

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A deeply embedded companion to LKH?198

Cited by 106 publications

References 1 publication

Are protons still dominant at the knee of the cosmic-ray energy spectrum?

Are protons still dominant at the knee of the cosmic-ray energy spectrum?

Models of Diffusion of Galactic Cosmic Rays From Superbubbles

Particle acceleration at relativistic shock waves

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