Simulation of Plasmoid Creation near a Rotating Black Hole

Relativistic jet phenomena are most often observed in the vicinity of black holes, where the surrounding plasma accretion plays an important role in the formation of these jets. The presence of a magnetic field is crucial since it has a significant effect on the accretive behaviour of a plasma. Primarily, the magnetic field links the central source with the ambient plasma and can be considered as a set of wires which can transport energy toward the black hole and away by means of MHD waves. Moreover, the magnetic field is able to collimate the plasma flow, which gives rise to a relativistic jet formation. To investigate the behaviour of a magnetized plasma accretion around a spinning black hole we use a string approach, which allows to depict the magnetized plasma as a set of magnetic flux tubes/string. It turned out that the interaction of the magnetic flux tube with the spinning black hole leads to an energy extraction process, which is attended by a relativistic jet creation. The influence of the reconnection process on the jet evolution leads to the formation of plasmoids, which move outward from the central source and remove energy and angular momentum. This process can be repeated over and over and finally the jet structure is composed of a chain of plasmoids which propagate along the spin hole axis

Energy balance in the course of relativistic magnetic reconnection

Magnetic reconnection plays an important role in space physics, for example, in Earth's magnetosphere, on the Sun, in the magnetospheres of magnetars, pulsars, black holes, etc. Reconnection starts with abrupt drop of plasma conductivity in a small part of a current sheet, so called, diffusion region. As a result electric field is generated and is transferred by relativistic MHD surface wave from the diffusion region to the current sheet which leads to decay of the disturbed part of the current sheet into a system of slow shocks. Plasma is highly accelerated and heated at the shock fronts forming outflow region with relativistic plasma jets and weak magnetic field (Semenov & Bernikov 1991). At some stage the reconnection process has to switch-off, then outflow regions must detach from the site where the electric field was initiated, and propagate along the current sheet as solitary waves (Tolstykh et al. 2005). The energy balance of relativistic reconnection is investigated in details. It is shown that magnetic and thermal energy from the inflow region is spent for acceleration and heating of the plasma in jets. It is interesting that the temperature of the plasma in the wake of the propagating outflow regions drops after each pulse of reconnection. This differ from usual explosion which heats the plasma behind the shock front (Tolstykh et al. 2007).