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.