A General Relativistic Magnetohydrodynamic Simulation of Jet Formation

Abstract

We have performed a fully three-dimensional general relativistic magnetohydrodynamic (GRMHD) simulation of jet formation from a thin accretion disk around a Schwarzschild black hole with a free-falling corona. The initial simulation results show that a bipolar jet (velocity ∼ 0.3c) is created as shown by previous two-dimensional axisymmetric simulations with mirror symmetry at the equator. The 3-D simulation ran over one hundred light-crossing time units (τ S = r S /c where r S ≡ 2GM/c 2 ) which is considerably longer than the previous simulations. We show that the jet is initially formed as predicted due in part to magnetic pressure from the twisting the initially uniform magnetic field and from gas pressure associated with shock formation in the region around r = 3r S . At later times, the accretion disk becomes thick and the jet fades resulting in a wind that is ejected from the surface of the thickened (torus-like) disk. It should be noted that no streaming matter from a donor is included at the outer boundary in the simulation (an isolated black hole not binary black hole). The wind flows outwards with a wider angle than the initial jet. The widening of the jet is consistent with the outward moving torsional Alfvén waves (TAWs). This evolution of disk-jet coupling suggests that the jet fades with a thickened accretion disk due to the lack of streaming material from an accompanying star.

Ultra-high-energy cosmic rays from low-luminosity active galactic nuclei

“…We limit the launching area of the jets to the innermost part of the disk located inside the BH ergosphere, where the rotational effects of the space-time are very strong. There are several general relativistic magnetohydrodynamic (GRMHD) codes, the result of which show that the jets can be magnetically driven from a thin disk located inside the BH ergosphere via a Penroselike process (Koide et al 1999;Nishikawa et al 2005;Mizuno et al 2007) or via the Blandford-Znajek mechanism (BZ, Blandford & Znajek (1977)) when a thick accretion disk is considered (McKinney 2006;McKinney & Blandford 2009). (But see the simulations by Fragile et al (2012), where the BZ driven jet does not depend on the disk thickness.)…”

Shocks in relativistic transverse stratified jets

“…In order to study the effects of the jet transverse stratification, we elaborate a two-component jet model according to the jet formation scenarios (Blandford & Znajek 1977;Blandford & Payne 1982;Sauty & Tsinganos 1994;Meliani et al 2006a) and numerical simulation (Koide et al 2000;Nishikawa et al 2005;McKinney & Blandford 2009). We adopt a two-component jet model with various kinetic energy flux distributions between the inner-outer jets.…”

Numerical modelling of the lobes of radio galaxies in cluster environments – III. Powerful relativistic and non-relativistic jets

“…Extending this to relativistic magnetohydrodynamics (RMHD) many models have been created focusing on the central region and the formation of the jets (e.g. Koide, Shibata & Kudoh 1999;Meier, Koide & Uchida 2001;Nishikawa et al 2005;McKinney & Blandford 2009;Tchekhovskoy, Narayan & McKinney 2011;McKinney, Tchekhovskoy & Blandford 2012). Previous RMHD models of the evolution of the jets themselves have made the simplest possible assumption of injecting material with a toroidal magnetic field into a uniform unmagnetized (Jones 1988;van Putten 1996;Mignone et al 2010) or magnetized (Nishikawa et al 1998;Komissarov 1999;Leismann et al 2005;van Putten 2015), but otherwise simple medium, instead of using a more realistic environment.…”