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We study the stability properties of hydrodynamic shocks with finite Mach numbers. The linear analysis supplements previous analyses which took the strong shock limit. We derive the linearised equations for a general specific heat ratio as…

Astrophysics · Physics 2009-11-13 Babulakshmanan Ramachandran , Michael D. Smith

The energy partition in high Mach number collisionless shock waves is central to a wide range of high-energy astrophysical environments. We present a new theoretical model for electron heating that accounts for the energy exchange between…

High Energy Astrophysical Phenomena · Physics 2024-10-22 Arno Vanthieghem , Vasileios Tsiolis , Anatoly Spitkovsky , Yasushi Todo , Kazuhiro Sekiguchi , Frederico Fiuza

Recent X-ray observations of merger shocks in galaxy clusters have shown that the post-shock plasma is two-temperature, with the protons hotter than the electrons. By means of two-dimensional particle-in-cell simulations, we study the…

High Energy Astrophysical Phenomena · Physics 2017-12-27 Xinyi Guo , Lorenzo Sironi , Ramesh Narayan

We measure the thermal electron energization in 1D and 2D particle-in-cell (PIC) simulations of quasi-perpendicular, low-beta ($\beta_p=0.25$) collisionless ion-electron shocks with mass ratio $m_i/m_e=200$, fast Mach number…

Space Physics · Physics 2025-04-15 Aaron Tran , Lorenzo Sironi

Electron accelerations at high Mach number collision-less shocks are investigated by means of two-dimensional electromagnetic Particle-in-Cell simulations with various Alfven Mach numbers, ion-to-electron mass ratios, and the upstream…

High Energy Astrophysical Phenomena · Physics 2013-11-01 Yosuke Matsumoto , Takanobu Amano , Masahiro Hoshino

Low Mach number, high beta fast mode shocks can occur in the magnetic reconnection outflows of solar flares. These shocks, which occur above flare loop tops, may provide the electron energization responsible for some of the observed hard…

Solar and Stellar Astrophysics · Physics 2013-03-01 Jaehong Park , Chuang Ren , Jared C. Workman , Eric G. Blackman

Recent X-ray observations of merger shocks in galaxy clusters have shown that the post-shock plasma is two-temperature, with the protons being hotter than the electrons. In this work, the second of a series, we investigate by means of…

High Energy Astrophysical Phenomena · Physics 2018-05-23 Xinyi Guo , Lorenzo Sironi , Ramesh Narayan

Adiabatic and non-adiabatic electron dynamics have been proposed to explain electron heating across collisionless shocks. We analyze the evolution of the suprathermal electrons across 310 quasi-perpendicular shocks with $1.7<M_A<48$ using…

Space Physics · Physics 2024-02-27 Ahmad Lalti , Yuri V. Khotyaintsev , Daniel B. Graham

We investigate the Mach number dependence of the radiative overstability of shocks. We find that the stability of radiative shocks increases with decreasing Mach number, with the result that M=2 shocks require cooling exponents < -1.2 to be…

Astrophysics · Physics 2009-11-11 J. M. Pittard , M. S. Dobson , R. H. Durisen , J. E. Dyson , T. W. Hartquist , J. T. O'Brien

Using Magnetospheric Multiscale (MMS) observations at the Earth's quasi-parallel bow shock we demonstrate that electrons are heated by two different mechanisms: a quasi-adiabatic heating process during magnetic field compression,…

Space Physics · Physics 2020-12-09 Krzysztof Stasiewicz , Bengt Eliasson

High Mach number collisionless shocks are found in planetary systems and supernova remnants (SNRs). Electrons are heated at these shocks to the temperature well above the Rankine-Hugoniot prediction. However processes responsible for…

High Energy Astrophysical Phenomena · Physics 2020-11-25 Artem Bohdan , Martin Pohl , Jacek Niemiec , Paul Morris , Yosuke Matsumoto , Takanobu Amano , Masahiro Hoshino

We study the suprathermal electron acceleration mechanism in a perpendicular magnetosonic shock wave in a high Mach number regime by using a particle-in-cell simulation. We find that shock surfing/surftron acceleration producing the…

Astrophysics · Physics 2009-11-07 M. Hoshino , N. Shimada

Electron acceleration to non-thermal energies is known to occur in low Mach number (M<5) shocks in galaxy clusters and solar flares, but the electron acceleration mechanism remains poorly understood. Using two-dimensional (2D)…

High Energy Astrophysical Phenomena · Physics 2014-11-26 Xinyi Guo , Lorenzo Sironi , Ramesh Narayan

The existence and properties of low Mach-number ($M \gtrsim 1$) electrostatic collisionless shocks are investigated with a semi-analytical solution for the shock structure. We show that the properties of the shock obtained in the…

A full particle simulation study is carried out for studying microinstabilities generated at the shock front of perpendicular collisionless shocks. The structure and dynamics of shock waves are determined by Alfven Mach number and plasma…

Plasma Physics · Physics 2015-06-04 Takayuki Umeda , Yoshitaka Kidani , Shuichi Matsukiyo , Ryo Yamazaki

In systems accreting well below the Eddington rate, the plasma in the innermost regions of the disk is collisionless and two-temperature, with the ions hotter than the electrons. Yet, whether a collisionless faster-than-Coulomb energy…

High Energy Astrophysical Phenomena · Physics 2015-06-23 Lorenzo Sironi , Ramesh Narayan

Seventy crossings of the Earths bow shock by the THEMIS satellites have been used to study thermal electron heating in collisionless, quasi-perpendicular shocks. It was found that the temperature increase of thermal electrons differed from…

Plasma Physics · Physics 2013-02-11 F. S. Mozer , David Sundkvist

Nonrelativistic electrostatic unmagnetized shocks are frequently observed in laboratory plasmas and they are likely to exist in astrophysical plasmas. Their maximum speed, expressed in units of the ion acoustic speed far upstream of the…

Plasma Physics · Physics 2015-06-15 ME Dieckmann , H Ahmed , G Sarri , D Doria , I Kourakis , L Romagnani , M Pohl , M Borghesi

Energy dissipation in collisionless shocks is a key mechanism in various astrophysical environments. Its non-linear nature complicates analytical understanding and necessitate Particle-in-Cell (PIC) simulations. This study examines the…

High Energy Astrophysical Phenomena · Physics 2024-12-20 Mohamad Shalaby

We report temperature and density dependences of the spin susceptibility of strongly interacting electrons in Si inversion layers. We measured (i) the itinerant electron susceptibility $\chi^*$ from the Shubnikov-de Haas oscillations in…

Strongly Correlated Electrons · Physics 2018-10-09 V. M. Pudalov , A. Yu. Kuntsevich , M. E. Gershenson , I. S. Burmistrov , M. Reznikov
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