Pair production, Comptonization and dynamics in astrophysical plasmas

Hydrodynamics, magnetohydrodynamics, and astrophysical plasmas

1 Introduction It is not uncommon to encounter the assertion that the dynamical evolution of the large-scale bulk velocity v of a collisionless gas is not described by the hydrodynamic (HD) equations. A favorite " reason " is the statement that pressure cannot be defined in the absence of collisions. Then in some quarters it is believed that the large-scale bulk dynamics of a swirling magnetize...

Magnetic Reconnection in Astrophysical and Laboratory Plasmas

Magnetic reconnection is a topological rearrangement of magnetic field that converts magnetic energy to plasma energy. Astrophysical flares, from the Earth’s magnetosphere to γ -ray bursts and sawtooth crashes in laboratory plasmas, may all be powered by reconnection. Reconnection is essential for dynamos and the large-scale restructuring known as magnetic self-organization. We review reconnect...

Turbulence and Magnetic Fields in Astrophysical Plasmas

Magnetic fields permeate the Universe. They are found in planets, stars, accretion discs, galaxies, clusters of galaxies, and the intergalactic medium. While there is often a component of the field that is spatially coherent at the scale of the astrophysical object, the field lines are tangled chaotically and there are magnetic fluctuations at scales that range over orders of magnitude. The cau...

Pair production in thermal plasmas: a computer model

A computer code has been developed to follow the processes of electronpositron pair production, annihilation, bremsstrahlung and Comptonization in a slab of mildly relativistic thermal plasma. The resulting equilibrium solutions are compared with the semi-analytic calculations of Svensson[1] .

Nuclear Excitation Processes in Astrophysical Plasmas