Speaker
Description
Accretion onto black holes requires angular momentum to be transported outward, yet the mechanisms that control this process, especially in strongly magnetized, rapidly spinning systems, remain uncertain. We investigate this using high-resolution 3D simulations of magnetized flows onto a rapidly spinning black hole, comparing weakly magnetized disks with strongly magnetized flows. The trend is unambiguous: angular momentum transport becomes dramatically more efficient as magnetic flux builds up. In the strongly magnetized state, large-scale magnetic stresses dominate the flow, driving a net outward angular momentum flux and extracting rotational energy through the Blandford–Znajek mechanism. Winds and jets provide additional channels for removing mass and angular momentum, fundamentally altering how accretion proceeds. Our results show that accretion is not governed by turbulence alone. Instead, it is controlled by the competition between small-scale turbulence and coherent magnetic structure, with ordered magnetic stresses taking over in the magnetically saturated regime. These stresses are modulated by episodic magnetic eruptions that briefly suppress accretion and destabilize jets, producing variability on timescales comparable to X-ray flares in active galactic nuclei. After eruptions, magnetorotational instabilities help in recovering magnetic flux back to saturated levels. This work sheds light on how magnetic structure governs transport and variability, linking accretion state, jet activity, and observed timing behavior in black hole systems.
