Shock wave

About: Shock wave is a research topic. Over the lifetime, 36184 publications have been published within this topic receiving 635848 citations. The topic is also known as: Shock waves & shockwave.

THREE-DIMENSIONAL GAS DYNAMIC SIMULATION OF THE INTERACTION BETWEEN THE EXOPLANET WASP-12b AND ITS HOST STAR

Abstract: Hubble Space Telescope transit observations in the near-UV performed in 2009 made WASP-12b one of the most "mysterious" exoplanets; the system presents an early ingress, which can be explained by the presence of optically thick matter located ahead of the planet at a distance of ~4-5 planet radii. This work follows previous attempts to explain this asymmetry with an exospheric outflow or a bow shock, induced by a planetary magnetic field, and provides a numerical solution of the early ingress, though we did not perform any radiative transfer calculation. We performed pure 3D gas dynamic simulations of the plasma interaction between WASP-12b and its host star and describe the flow pattern in the system. In particular, we show that the overfilling of the planet's Roche lobe leads to a noticeable outflow from the upper atmosphere in the direction of the and points. Due to the conservation of the angular momentum, the flow to the point is deflected in the direction of the planet's orbital motion, while the flow toward is deflected in the opposite direction, resulting in a non-axisymmetric envelope, surrounding the planet. The supersonic motion of the planet inside the stellar wind leads to the formation of a bow shock with a complex shape. The existence of the bow shock slows down the outflow through the and points, allowing us to consider a long-living flow structure that is in the steady state.

The time scale for the transition to turbulence in a high Reynolds number, accelerated flow

Abstract: An experiment is described in which an interface between materials of different density is subjected to an acceleration history consisting of a strong shock followed by a period of deceleration The resulting flow at this interface, initiated by the deposition of strong laser radiation into the initially well characterized solid materials, is unstable to both the Richtmyer–Meshkov (RM) and Rayleigh–Taylor (RT) instabilities These experiments are of importance in their ability to access a difficult experimental regime characterized by very high energy density (high temperature and pressure) as well as large Reynolds number and Mach number Such conditions are of interest, for example, in the study of the RM/RT induced mixing that occurs during the explosion of a core-collapse supernova Under these experimental conditions, the flow is in the plasma state and given enough time will transition to turbulence By analysis of the experimental data and a corresponding one-dimensional numerical simulation of the

Heating and Non-thermal Particle Acceleration in Relativistic, Transverse Magnetosonic Shock Waves in Proton-Electron-Positron Plasmas

Abstract: We report the results of 1D particle-in-cell simulations of ultrarelativistic shock waves in proton-electron-positron plasmas. We consider magnetized shock waves, in which the upstream medium carries a large scale magnetic field, directed transverse to the flow. Relativistic cyclotron instability of each species as the incoming particles encounter the increasing magnetic field within the shock front provides the basic plasma heating mechanism. The most significant new results come from simulations with mass ratio $m_p/m_\pm = 100$. We show that if the protons provide a sufficiently large fraction of the upstream flow energy density (including particle kinetic energy and Poynting flux), a substantial fraction of the shock heating goes into the formation of suprathermal power-law spectra of pairs. Cyclotron absorption by the pairs of the high harmonic ion cyclotron waves, emitted by the protons, provides the non-thermal acceleration mechanism. As the proton fraction increases, the non-thermal efficiency increases and the pairs' power-law spectra harden. We suggest that the varying power law spectra observed in synchrotron sources powered by magnetized winds and jets might reflect the correlation of the proton to pair content enforced by the underlying electrodynamics of these sources' outflows, and that the observed correlation between the X-ray spectra of rotation powered pulsars with the X-ray spectra of their nebulae might reflect the same correlation.

On Beaming Effects in Afterglow Light Curves

Abstract: The most luminous gamma-ray bursts can be explained in terms of models involving stellar-mass central engines only if the ejecta are beamed. As was pointed out by Rhoads, the dynamics of the blast wave, formed by the beamed ejecta sweeping the external gas, can be significantly modified by the sideways expansion. This is because, in this case, the surface of the blast-wave increases faster than it does just as a result of the radial divergence, so the blast wave deceleration rate increases faster. According to analytical estimates, the effect becomes important shortly after the bulk Lorentz factor of the blast wave drops below the inverse of the initial opening angle of the beamed ejecta and is accompanied by a sharp break in the afterglow light curve. However, our numerical studies, which follow both the dynamical evolution of the blast wave and the evolution of the electron energy distribution and take into account the light-travel effects related to the lateral size of the source, show that the break of the light curve is weaker and much smoother than the one analytically predicted. A prominent break emerges only for a model without the sideways expansion.