Jet Formation from Rotating Magnetized Objects

Jet formation is connected most probably with matter acceleration from the vicinity of rotating magnetized bodies. It is usually related to the mass outflows and ejection from accretion disks around black holes. Problem of jet collimation is discussed. Collapse of a rotating magnetized body during star formation or supernovae explosion may lead to a jet-like mass ejection for certain angular velocity and magnetic field distributions at the beginning of the collapse. Jet formation during magnetorotational explosion is discussed basing on the numerical simulation of collapse of magnetized bodied with quasi-dipole field.Comment: Will be published in the proc. of 20th Texas Symposium, Austin, Texas 7 pages, 7 picture

Electromagnetohydrodynamics

Interaction of plasma flow with a magnetic obstacle is a frequent process in many laser-plasma experiments in the laboratory, and is an important event in many astrophysical objects such as X-ray pulsars, AGN, GRB etc. As a result of plasma penetration through the magnetic wall we could expect a formation of magnetohydrodynamic (MHD) shock waves, as well as of electromagnetic (EM) ones. To study these processes we need equations following from hydrodynamic and Maxwell equations, which in the limiting situations describe MHD and EM waves, and are valid for the general case, when both phenomena are present. Here we derive a set of equations following from hydrodynamic and Maxwell equations, without neglecting a displacement current, needed for a formation of EM waves. We find a dispersion equation describing a propagation of a weak linear wave in a magnetized plasma along the $x$ axis, perpendicular to the magnetic field $H_y(x)$, which contains MHD, hydrodynamic and EM waves in the limiting cases, and some new types of behaviour in a general situation. We consider a plasma with zero viscosity and heat conductivity, but with a finite electric conductivity with a scalar coefficient.Comment: 8 papers, 8 figures, 1 table, to be submitted in PR

Magnetorotational supernovae

We present the results of 2D simulations of the magnetorotational model of a supernova explosion. After the core collapse the core consists of rapidly a rotating proto-neutron star and a differentially rotating envelope. The toroidal part of the magnetic energy generated by the differential rotation grows linearly with time at the initial stage of the evolution of the magnetic field. The linear growth of the toroidal magnetic field is terminated by the development of magnetohydrodynamic instability, leading to drastic acceleration in the growth of magnetic energy. At the moment when the magnetic pressure becomes comparable with the gas pressure at the periphery of the proto-neutron star $\sim 10-15$km from the star centre the MHD compression wave appears and goes through the envelope of the collapsed iron core. It transforms soon to the fast MHD shock and produces a supernova explosion. Our simulations give the energy of the explosion $0.6\cdot 10^{51}$ ergs. The amount of the mass ejected by the explosion is $\sim 0.14M_\odot$. The implicit numerical method, based on the Lagrangian triangular grid of variable structure, was used for the simulations.Comment: Revised version. Submitted to the MNRA