Dynamics of Relativistic Magnetized Flows.

Magnetically-dominated relativistic outflows are naturally generated as extentions of magnetospheres of rapidly rotating black holes and neutron stars. They are powered by the rotational energy of the central object and carry out this energy mainly in the form of Poynting flux. When this energy is dissipated via interaction with external medium, strong sources of non-thermal electromagnetic emission are produced. This is how the origin of Pulsar Wind Nebulae, Radio Galaxies, Quasars, Galactic Micro-quasars and GRB jets is often explained in modern theoretical astrophysics. However, these theories are based on simplistic analytical and semi-analytical models of the flow dynamics and the numerical studies have been confined mostly to the case of axisymmetric flows so far. On the other hand, many magnetic configurations are known to be unstable with non-axisymmetric modes growing at highest rates in linear regime. Until the non-linear effects of these instabilities are fully understood these theories are not complete. In fact, a number of long standing problems in the theory of Pulsar Wind Nebulae and Extragalactic Jets could reflect the limitations of imposed axisymmetry. One of such problems is the very slow rate of conversion of the Poynting flux into the kinetic energy, the so-called 'sigma-problem'. The randomization of magnetic field due to the instabilities may significantly improve the efficiency because the dynamics of random magnetic field mimics that of ultra-relativistic gas. We propose to use massive parallel relativistic MHD simulations in order to study the complex three-dimensional dynamics of magnetically dominated relativistic flows. The recent progress in development of robust numerical schemes for RMHD and Adaptive Mesh Refinement algorithms combined with availability of powerful computer clusters make this project both feasible and timely. We have been involved in the development of Computational Astrophysics of Relativistic Plasma from the very beginning and have accumulated internationally-recognised expertise in the area.