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Linear stability of a plane shock waves in ultrarelativistic anisotropic hydrodynamics is investigated. The properties of the amplitudes of perturbations of physical quantities are studied depending on the components of the wave vector of a…

Nuclear Theory · Physics 2023-09-21 Aleksandr Kovalenko

We study the evolution of non-linear circularly polarised Alfven waves by solving numerically the time-dependent equations of magnetohydrodynamics (MHD) in one dimension. We examine the behaviour of the waves and find that different…

Astrophysics · Physics 2009-11-10 Rim Turkmani , Ulf Torkelsson

We study large-amplitude, very oblique Alfv\'en waves at low $\beta$, with small gradient length scales, comparable to the ion inertial scale $d_i$. Such waves have large density fluctuations, and slight dispersion from finite-frequency and…

Plasma Physics · Physics 2023-11-10 Alfred Mallet

The effect of magnetic shear and shear flow on local gravitationally induced instabilities is investigated. A simple model is constructed allowing for an arbitrary entropy gradient and a shear plasma flow in the Boussinesq approximation. A…

Astrophysics · Physics 2009-11-06 Gregory G. Howes , Steven C. Cowley , James C. McWilliams

The solar wind upstream of Mars's bow shock can be described in terms of Alfv\'enic turbulence, with an incompressible energy cascade rate of $10^{-17}$ J m$^{-3}$ s$^{-1}$ at magnetohydrodynamics (MHD) scales. The solar wind has more…

Solar and Stellar Astrophysics · Physics 2024-06-26 Norberto Romanelli , Christopher M. Fowler , Gina A. DiBraccio , Jared R. Espley , Jasper S. Halekas

We investigate conditions under which kink magnetohydrodynamic waves propagating along photospheric uniformly twisted flux tubes with axial mass flows become unstable as a consequence of the Kelvin-Helmholtz instability. We employed the…

Solar and Stellar Astrophysics · Physics 2015-06-11 I. Zhelyazkov , T. V. Zaqarashvili

During the last decade it has become evident that the magnetorotational instability is at the heart of the enhanced angular momentum transport in weakly magnetized accretion disks around neutron stars and black holes. In this paper, we…

Astrophysics · Physics 2009-11-10 Martin E. Pessah , Dimitrios Psaltis

In several space dimensions, scalar shock waves between two constant states u $\pm$ are not necessarily planar. We describe them in detail. Then we prove their asymptotic stability, assuming that they are uniformly non-characteristic. Our…

Analysis of PDEs · Mathematics 2021-03-18 Denis Serre

We study the first-order Fermi acceleration process at parallel shock waves by means of Monte Carlo simulations. A 'realistic' model of the magnetic field turbulence is applied involving sinusoidal waves imposed on the background mean field…

Astrophysics · Physics 2007-05-23 Jacek Niemiec , Michal Ostrowski

We use 2D and 3D hybrid (kinetic ions - fluid electrons) simulations to investigate particle acceleration and magnetic field amplification at non-relativistic astrophysical shocks. We show that diffusive shock acceleration operates for…

High Energy Astrophysical Phenomena · Physics 2015-06-17 Damiano Caprioli , Anatoly Spitkovsky

In the absence of magnetic fields and cosmic rays, radiative cooling laws with a range of dependences on temperature affect the stability of interstellar gas. For about four and a half decades, astrophysicists have recognised the importance…

Astrophysics of Galaxies · Physics 2011-08-08 T. W. Hartquist , A. Y. Wagner , S. A. E. G. Falle , J. M. Pittard , S. Van Loo

It is well-recognized that the presence of magnetic fields will lead to anisotropic energy cascade and dissipation of astrophysical turbulence. With the diffusion approximation and linear dissipation rates, we study the cascade and damping…

Solar and Stellar Astrophysics · Physics 2009-03-31 Yanwei Jiang , Siming Liu , Vahé Petrosian

We perform a series of two-dimensional magnetohydrodynamic simulations of the rotational core-collapse of a magnetized massive star. We employ a realistic equation of state and take into account the neutrino cooling by the so-called leakage…

Astrophysics · Physics 2009-11-10 Tomoya Takiwaki , Kei Kotake , Shigehiro Nagataki , Katsuhiko Sato

The physics of instabilities in the precursor of relativistic collisionless shocks is of broad importance in high energy astrophysics, because these instabilities build up the shock, control the particle acceleration process and generate…

High Energy Astrophysical Phenomena · Physics 2015-06-18 M. Lemoine , G. Pelletier , L. Gremillet , I. Plotnikov

Shock waves play an important role in turbulent astrophysical media by compressing the gas and dissipating the turbulent energy into the thermal energy. We here study shocks in magnetohydrodynamic turbulence using high-resolution…

High Energy Astrophysical Phenomena · Physics 2019-04-17 Junseong Park , Dongsu Ryu

Collisionless regime kinetic models for coherent nonlinear Alfven wave dynamics are studied using fluid moment equations with an approximate closure anzatz. Resonant particle effects are modelled by incorporating an additional term…

Plasma Physics · Physics 2009-10-30 M. V. Medvedev , P. H. Diamond

Shock parameters at Earth's bow shock in rare instances can approach the Mach numbers predicted at supernova remnants. We present our analysis of a high Alfv\'en Mach number ($M_A= 27$) shock utilizing multipoint measurements from the…

We investigate the conditions under which parallel-propagating Alfv\'en/ion-cyclotron waves are driven unstable by an isotropic ($T_{\perp \alpha} = T_{\parallel\alpha}$) population of alpha particles drifting parallel to the magnetic field…

Collisional self-interactions occurring in protostellar jets give rise to strong shocks, the structure of which can be affected by radiative cooling within the flow. To study such colliding flows, we use the AstroBEAR AMR code to conduct…

High Energy Astrophysical Phenomena · Physics 2022-12-13 R. N. Markwick , A. Frank , J. Carroll-Nellenback , B. Liu , E. G. Blackman , S. V. Lebedev , P. M. Hartigan

The phenomena of self-sustained shock wave oscillations over conical bodies with a blunt axisymmetric base subject to uniform high-speed flow are investigated in a hypersonic wind tunnel at Mach number $M = 6$. The flow and shock wave…

Fluid Dynamics · Physics 2022-06-07 Vaisakh Sasidharan , Subrahmanyam Duvvuri