Relativistic reconnection and collisionless shocks


Relativistic plasma plays very important role in the activity of a number of luminous astrophysical objects, in particular, gamma-ray bursts which are one of the hottest subjects of research during the last decade. Reconnection and collisionless shocks are two major accelerators of charged particles. Both phenomena are thoroughly studied (although not understood completely yet) in the heliospheric conditions but are only barely touched for the conditions of ultra-relativstic plasmas. In the heliospheric environment reconnection and collisionless shocks occur in different conditions, since the former require existence of a current sheet with low magnetic field, while the latter are usually magnetized. Relativistic shocks, however, often occur in the low magnetic field interstellar medium. It is expected that in the gamma-ray burst shocks almost unmagnetized current filaments develop which are separated by magnetic sheets. Thus, in both cases magnetized regions co-exist with the regions of almost complete demagnetization, and there is plasma exchange between these regions. Such similarity (albeit limited) of the reconnecting current sheet of filamentary relativistic shock has been never exploited in studies of these two phenomena. The objective of the proposed research is to develop a general approach to relativistic shocks and current sheet equilibria, which will allow to establish common features of the relativistic plasma systems with intermittent regions of weak and strong magnetic field.


Michael Gedalin (Ben-Gurion University, Beer-Sheva, Israel, team leader)
Michael Balikhin (ACSE, Sheffield University, Sheffield, UK)
Vladimir Krasnoselskikh (LPCE/CNRS, Orleans, France)
Mikhail Medvedev (University of Kansas, Kansas, USA)
Anatoly Spitkovsky (Princeton University, Princeton, USA)
Andris Vaivads (Swedish Insitute of Space Physics, Uppsala, Sweden)
Silvia Perri (ISSI, young scientist)
Richard Boynton (ACSE, University of Sheffield, Sheffield, UK, student)


First meeting:25-31.01.09

First meeting:

SpeakerTopicOperative comments (what to do)
V. KrasnoselskikhNonstationary shocksDependence of the non-stationarity (reformation) on the Mach number and v/c
A. SpitkovskyRelativistic shock simulationsDefinition of the parameter space and transitions
M. MedvedevWeibel instabilityComprehensive study of the k-space, and n(beam)/n
S. PerriSuperdiffusive transportApplications to NR and UR regimes
A. VaivadsObservations of reconnectionStabitlity of current sheets (both directions)
M. BalikhinRegimes and scales in shocksDependence of the scales on M and v/c
M. GedalinIon motion in quasiperpendicular shocksIon escape and injection for very-high M
R. BoyntonTHEMIS observations of mirror modes in the magnetosheathMirror modes in SNR shock downstream ?

The Team
Standing (right to left): Richard Boynton, Andris Vaivads, Volodya Krasnoselskikh, Misha Balikhin, Anatoly Spitkovsky, Mikhail Medvedev.
Sitting (right to left): Silvia Perri, Michael Gedalin.

Valid HTML 4.01!