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We examine limits to the energy to which cosmic rays can be accelerated by relativistic shocks, showing that acceleration of light ions as high as 100 EeV is unlikely. The implication of our estimates is that if ultra-high energy cosmic…

High Energy Astrophysical Phenomena · Physics 2017-11-15 AR Bell , AT Araudo , JH Matthews , KM Blundell

We have investigated proton acceleration in the forward direction from a near-critical density hydrogen gas jet target irradiated by a high intensity (10^18 W/cm^2), short-pulse (5 ps) laser with wavelength of 1.054 micron. We observe the…

We consider the acceleration of electrons in vacuum by means of the circularly-polirized electromagnetic wave, propagating along a magnetic field. We show that the electron energy growth, when using ultra-short and ultra-intense laser…

Accelerator Physics · Physics 2014-05-13 Robert Melikian

We examine the hypothesis that there exists a simple scaling between the observed velocities of jets found in Young Stellar Objects (YSOs) and jets found in Active Galactic Nuclei (AGN). We employ a very simplified physical model of the jet…

Astrophysics · Physics 2009-11-07 Daniel J. Price , James E. Pringle , Andrew R. King

Relativistic shocks are considered efficient accelerators of charged particles and play crucial roles in high-energy astrophysical phenomena, such as gamma-ray bursts and pulsar winds. This study focuses on positron accelerations in…

High Energy Astrophysical Phenomena · Physics 2026-02-25 Shori Arai , Yosuke Matsumoto

Particle acceleration at plasma shocks appears to be ubiquitous in the universe, spanning systems in the heliosphere, supernova remnants, and relativistic jets in distant active galaxies and gamma-ray bursts. This review addresses some of…

Astrophysics · Physics 2008-11-26 Matthew G. Baring

Almost all sources of high energy particles and photons are associated with jet phenomena. Prominent sources of such highly relativistic outflows are pulsar winds and Active Galactic Nuclei. The current understanding of these jets assumes…

High Energy Astrophysical Phenomena · Physics 2010-09-01 Thomas Burkart , Oliver Elbracht , Urs Ganse , Felix Spanier

We critically assess limits on the maximum energy of protons accelerated within superbubbles around massive stellar clusters, considering a number of different scenarios. In particular, we derive under which circumstances acceleration of…

High Energy Astrophysical Phenomena · Physics 2022-08-03 Thibault Vieu , Brian Reville , Felix Aharonian

In this article, we concentrate on the basic physics of relativistic plasma wave accelerators. The generation of relativistic plasma waves by intense lasers or electron beams in low-density plasmas is important in the quest for producing…

Accelerator Physics · Physics 2017-05-31 R. Bingham , R. Trines

The energetics of electromagnetic acceleration of ultra-high-energy cosmic rays (UHECRs) is constrained both by confinement of a particle within an acceleration site and by radiative energy losses of the particle in the confining magnetic…

Astrophysics · Physics 2009-11-07 Mikhail V. Medvedev

We study the acceleration of electrons and protons interacting with localized, multiple, small-scale dissipation regions inside an evolving, turbulent active region. The dissipation regions are Unstable Current Sheets (UCS), and in their…

Astrophysics · Physics 2009-11-10 L. Vlahos , H. Isliker , F. Lepreti

We derive the maximum accelerated particle energy from first-order and second-order Fermi acceleration at nonrelativistic and relativistic shocks for explosions taking place in a uniform surrounding medium. Second-order stochastic processes…

Astrophysics · Physics 2007-05-23 Charles D. Dermer

Laboratory experiments to explore plasma conditions and stimulated particle acceleration can illuminate aspects of the cosmic particle acceleration process. Here we discuss the cosmic-ray candidate source object variety, and what has been…

High Energy Astrophysical Phenomena · Physics 2009-12-15 Roland Diehl

We review recent developments in particle acceleration by Poynting flux using plasma kinetic simulations, and discuss their potential applications to gamma-ray burst phenomenology

Astrophysics · Physics 2007-05-23 Edison Liang , Koichi Noguchi

We study a type of particle acceleration that operates via neutron-proton conversion in inelastic nuclear collisions. This mechanism can be expected for relativistic shocks at subphotospheres if relativistic outflows contain neutrons. Using…

High Energy Astrophysical Phenomena · Physics 2015-06-15 Kazumi Kashiyama , Kohta Murase , Peter Mészáros

Counterpropagating Alfv\'en waves are ubiquitously observed in many astrophysical environments, such as a star surface and a planetary foreshock. We discuss an efficient particle acceleration mechanism in two counterpropagating circularly…

High Energy Astrophysical Phenomena · Physics 2023-04-06 S. Isayama , K. Takahashi , S. Matsukiyo , T. Sano

We report a laser wakefield acceleration of electron beams up to 130 MeV from laser-driven 4-mm long nitrogen gas jet. By using a moderate laser intensity (3.5*10^18 W.cm^(-2)) and relatively low plasma densities (0.8*10^18 cm^(-3) to…

Plasma Physics · Physics 2014-10-14 Mengze Tao , Nasr A. M. Hafz , Song Li , Mohammad Mirzaie , Liming Chen , Fei He , Ya Cheng , Jie Zhang

AGNs jets are known to display relativistic motion on parsec scales but the accelerating mechanism as well as the exact bulk Lorentz factor of the flow are still a matter of discussion. Under certain assumptions, a plasma can be accelerated…

High Energy Astrophysical Phenomena · Physics 2014-11-18 Thomas Vuillaume , Pierre-Olivier Petrucci , Gilles Henri

Acceleration of electrons in vacuum directly by intense laser fields, often termed vacuum laser acceleration (VLA), holds great promise for the creation of compact sources of high-charge, ultrashort, relativistic electron bunches. However,…