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</o:shapelayout></xml><![endif]--></head><body lang=EN-GB link=blue vlink=purple><div class=WordSection1><p class=MsoNormal>All welcome for the following seminar:<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Colville 4.05, Tuesday 10<sup>th</sup> March 3pm<br><br>Dr. Antoine Bret, Universidad Castilla La Mancha, Spain<o:p></o:p></p><p class=MsoNormal><br><b>TITLE:</b> Gamma-Ray-Bursts, High-Energy-Cosmic-Rays and Collisionless Shocks in Plasmas<o:p></o:p></p><p class=MsoNormal><br><b>ABSTRACT: </b>Collisionless shocks in plasmas play an important role in space physics (Earth's bow shock) and astrophysics (supernova remnants, relativistic jets, gamma-ray bursts, high energy cosmic rays). While the formation of a fluid shock through the steepening of a large amplitude sound wave has been understood for long, there is currently no detailed picture of the mechanism responsible for the formation of a collisionless shock. After explaining their role in the physics of GRBs and High Energy Cosmic Rays, we’ll present the physical mechanism at work when an electromagnetic Weibel shock forms in pair plasmas. The predicted shock formation time is in good agreement with 2D and 3D particle-in-cell simulations of counter-streaming pair plasmas. By predicting the shock formation time, experimental setups aiming at producing such shocks can be optimized to favourable conditions.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Cheers,<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Mark.<o:p></o:p></p><p class=MsoNormal><br><br><o:p></o:p></p></div></body></html>