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An ion beam can destabilize Alfv\'en/ion-cyclotron waves and magnetosonic/whistler waves if the beam speed is sufficiently large. Numerical solutions of the hot-plasma dispersion relation have previously shown that the minimum beam speed…

Space Physics · Physics 2013-01-30 Daniel Verscharen , Benjamin D. G. Chandran

The injection rate of suprathermal protons into the diffusive shock acceleration process should vary strongly over the surface of supernova remnant shocks. These variations and the absolute value of the injection rate are investigated. In…

Astrophysics · Physics 2007-05-23 H. J. Voelk , E. G. Berezhko , L. T. Ksenofontov

Magnetic energy around compact objects often dominates over plasma rest mass, and its dissipation can power the object luminosity. We describe a dissipation mechanism which works faster than magnetic reconnection. The mechanism involves two…

High Energy Astrophysical Phenomena · Physics 2021-07-28 Xinyu Li , Andrei M. Beloborodov , Lorenzo Sironi

Context. Supernova remnants are known as sources of galactic cosmic rays for their non-thermal emission of radio waves, X-rays, and gamma-rays. However, the observed soft broken power-law spectra are hard to reproduce within standard…

High Energy Astrophysical Phenomena · Physics 2016-08-31 Robert Brose , Igor Telezhinsky , Martin Pohl

The characteristics of Alfv\'en waves propagating in a direction oblique to the ambient magnetic field in a stellar wind environment are discussed. A kinetic formulation for a magnetized dusty plasma is adopted considering Maxwellian…

Plasma Physics · Physics 2022-03-22 L. B. De Toni , R. Gaelzer , L. F. Ziebell

The propagation and the evolution of Alfvenic pulses in the solar coronal arcades is investigated by means of MHD numerical simulations. Significant transverse oscillations in coronal loops, triggered by nearby flare events, are often…

Astrophysics · Physics 2009-11-10 Luca Del Zanna , Eveline Schaekens , Marco Velli

We have performed extensive two-dimensional magnetohydrodynamic simulations to study the amplification of magnetic fields when a supernova blast wave propagates into a turbulent interstellar plasma. The blast wave is driven by injecting…

High Energy Astrophysical Phenomena · Physics 2015-06-03 Fan Guo , Shengtai Li , Hui Li , Joe Giacalone , J. R. Jokipii , David Li

The origin and evolution of the 1/f power law observed in the energy spectrum of solar coronal and solar wind fluctuations at scales of around an hour is not entirely understood. Several existing theories aim at explaining it, involving…

Solar and Stellar Astrophysics · Physics 2022-10-26 Norbert Magyar , Tom Van Doorsselaere

We present a mechanism for the formation of the low frequency 1/f magnetic spectrum based on numerical solutions of a shell reduced-MHD model of the turbulent dynamics inside the sub-Alfv\'enic solar wind. We assign reasonably realistic…

Solar and Stellar Astrophysics · Physics 2015-06-04 A. Verdini , R. Grappin , R. Pinto , M. Velli

A Hamiltonian two-field gyrofluid model for kinetic Alfv\'en waves (KAWs) in a magnetized electron-proton plasma, retaining ion finite-Larmor-radius corrections and parallel magnetic field fluctuations, is used to study the inverse cascades…

Plasma Physics · Physics 2021-04-01 George Miloshevich , Dimitri Laveder , Thierry Passot , Pierre-Louis Sulem

We present a parameter study of simulations of fragmentation regulated by gravity, magnetic fields, ambipolar diffusion, and nonlinear flows. The thin-sheet approximation is employed with periodic lateral boundary conditions, and the…

Astrophysics · Physics 2011-12-20 Shantanu Basu , Glenn E. Ciolek , Wolf Dapp , James Wurster

We simulate time-dependent particle acceleration in the blast wave of a young supernova remnant (SNR), using a Monte Carlo approach for the diffusion and acceleration of the particles, coupled to an MHD code. We calculate the distribution…

High Energy Astrophysical Phenomena · Physics 2015-05-18 K. M. Schure , A. Achterberg , R. Keppens , Jacco Vink

Analytical expressions for the dispersion relations and polarizations of low-frequency waves in magnetized plasmas based on two-fluid model are obtained. The properties of waves propagating at different angles (to the ambient magnetic field…

Plasma Physics · Physics 2015-05-29 Jinsong Zhao

[SHORTENED VERSION] Observations of radio emission from young core-collapse supernovae (CCSNe) allow one to study the history of the pre-supernova stellar wind, trace the density structure of the ejected material, and probe the…

High Energy Astrophysical Phenomena · Physics 2024-10-11 I. Marti-Vidal , C-I. Bjornsson , M. A. Perez-Torres , P. Lundqvist , J. M. Marcaide

Proton energization at magnetic discontinuities generated by phase-steepened fronts of parallel propagating, large-amplitude Alfv\'enic fluctuation is studied using hybrid simulations. We find that dispersive effects yield to the collapse…

Plasma Physics · Physics 2021-04-07 C. A. González , A. Tenerani , L. Matteini , P. Hellinger , M. Velli

We examine the role of Alfven wave damping in heating the plasma in the magnetic funnels of magnetospheric accretion models of young stars. We study four different damping mechanisms of the Alfven waves: nonlinear, turbulent,…

Astrophysics · Physics 2015-05-27 M. J. Vasconcelos , V. Jatenco-Pereira , R. Opher

Constraints on the diffusion and acceleration parameters in five young supernova remnants (SNRs) are derived from the observed thickness of their X-ray rims, as limited by the synchrotron losses of the highest energy electrons, assuming…

Astrophysics · Physics 2009-11-11 E. Parizot , A. Marcowith , J. Ballet , Y. A. Gallant

Complete asymptotic expansions are developed for slow, Alfv\'en and fast magnetohydrodynamic waves at the base of an isothermal three-dimensional (3D) plane stratified atmosphere. Together with existing convergent Frobenius series solutions…

Solar and Stellar Astrophysics · Physics 2021-12-28 Paul S. Cally

The maximum energy of electrons in supernova remnant (SNR) shocks is typically limited by radiative losses, where the synchrotron cooling time equals the acceleration time. The low speed of shocks in a dense medium increases the…

High Energy Astrophysical Phenomena · Physics 2024-07-30 Vincenzo Sapienza , Marco Miceli , Oleh Petruk , Aya Bamba , Satoru Katsuda , Salvatore Orlando , Fabrizio Bocchino , Tracey DeLaney

Models for the synchrotron emission of gamma-ray burst afterglows suggest that the magnetic field is generated in the shock wave that forms as relativistic ejecta plow through the circum-burst medium. Transverse Weibel instability…

Astrophysics · Physics 2009-11-13 Milos Milosavljevic , Ehud Nakar