Abstract
The most promising mechanisms for producing and accelerating relativistic jets, and maintaining collimated structure of relativistic jets involve magnetohydrodynamical (MHD) processes. We have investigated the magnetic dissipation mechanism in relativistic jets via relativistic MHD simulations. We found that the relativistic jets involving a helical magnetic field are unstable for the current-driven kink instability, which leads to helically distorted structure in relativistic jets. We identified the regions of high current density in filamentary current sheets, indicative of magnetic reconnection, which are associated to the kink unstable regions and correlated to the converted regions of magnetic to kinetic energies of the jets. We also found that an over-pressured relativistic jet leads to the generation of a series of stationary recollimation shocks and rarefaction structures by the nonlinear interaction of shocks and rarefaction waves. The differences in the recollimation shock structure due to the difference of the magnetic field topologies and strengths may be observable through mm-VLBI observations and space-VLBI mission.
Highlights
Relativistic jets are ubiquitous features of many accreting compact object systems
We shortly review our findings for the magnetic dissipation in relativistic jets from recent MHD simulations of CD kink instabilities and recollimation shocks
We have shortly reviewed our recent work related on the magnetic dissipation in relativistic jets
Summary
Relativistic jets are ubiquitous features of many accreting compact object (mostly black hole) systems. The most promising MHD models for the acceleration and collimation of jets involve the presence of a magnetic field with foot points anchored to a rotating object (an accretion disk or a spinning neutron star or black hole). It is well known that current carrying plasma columns containing strong toroidal magnetic fields are unstable to non-axisymmetric perturbations Among these current-driven (CD) instabilities, the kink mode is the most violent. Magnetic reconnection via current driven instability leads to the conversion of Poynting flux to kinetic flux, which provides particle acceleration [12] Such magnetic dissipation would generate flares from a very small region of a few Schwarzschild radii in size; such flares would be moving very fast, essentially as “min-jets” within the slower jet medium [13,14]. We shortly review our findings for the magnetic dissipation in relativistic jets from recent MHD simulations of CD kink instabilities and recollimation shocks
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