Three-Dimensional Simulations of Vertical Magnetic Flux in the Immediate Vicinity of Black Holes

Abstract

This article reports on three-dimensional MHD simulations of non-rotating and rapidly rotating black holes and the adjacent black hole accretion disk magnetospheres. A particular emphasis is placed on the vertical magnetic flux that is advected inward from large radii and threads the equatorial plane near the event horizon. In both cases of non-rotating and rotating black holes, the existence of a significant vertical magnetic field in this region is like a switch that creates powerful jets. There are many similarities in the vertical flux dynamics in these two cases in spite of the tremendous enhancement of azimuthal twisting of the field lines and enhancement of the jet power because of an "ergospheric disk" in the Kerr metric. A three-dimensional approach is essential because two-dimensional axisymmetric flows are incapable of revealing the nature of the vertical flux near a black hole. Poloidal field lines from the ergospheric accretion region have been visualized in three dimensions and much of the article is devoted to a formal classification of the different manifestations of the vertical flux in the Kerr case.

Launching proton-dominated jets from accreting Kerr Black Holes: the case of M87

“…Inside r tr , the collapse of the plasma in the BL causes the poloidal magnetic flux to accumulate, suppressing therefore the generation of turbulence and diminishing heating via turbulent dissipation. Such a development has been verified also in the 3D MHD simulations of Igumenshchev (2008) and Punsly et al (2009). Therefore the disk ceases to radiate as black body and turns into an observationally dark region.…”

“…However, there is no reason to expect β < 1 in the innermost part of the disk, where the effect of the spin of the central accreting black hole becomes significant (see Punsly et al, 2009, and the references therein). MRI, Parker instability, reconnection in combination with the significant speed up of inflow may lead to the establishment of a large-scale poloidal MFs, whose corresponding energy could be comparable or even larger than the thermal energy of the embedded plasma .…”

“…On the other hand, MFs are still deformed by the frame-dragging effect, thus extracting angular momentum. The rotational energy is not extracted from the matter then, but directly from the central black hole (see Punsly & Coroniti , 1990;Punsly et al, 2009, for further details). Yet, the total amount extracted in this way will be negligible compared to the total rotational energy of the black hole so no spin-down is taken into account.…”

A Jet Source of Event Horizon Telescope Correlated Flux in M87

“…An interesting variant of the model of a strong tubular jet and a weak event horizon driven spine is the scenario in which the preponderance of the jet emission is emitted from just inside the ISCO, an "ergospheric disk jet." Three dimensional MHD simulations of ergospheric disk jets have been discussed in detail for a/M = 0.99 (Punsly et al 2009). These jets can be stronger sources of Poynting flux than jets that form outside of the ISCO.…”

Is the disc thermal state controlling the Blandford & Znajek/Blandford & Payne jet dichotomy?

“…But the complexity of the problem was such that no analytical approach has been found satisfactory. When it became feasible, 3D global GRMHD numerical simulations have been conducted and showed indeed the formation of a Poynting flux dominated region above the black hole, powered by its rotational energy ( [4][5][6][7][8] to cite only a few).…”