The Cosmic Battery and the Inner Edge of the Accretion Disk

NEB 15 – Recent Developments in Gravity

Contopoulos, Ioannis^1 ; Papadopoulos, Demetrios B^2

Research Center for Astronomy, Academy of Athens, Athens 11527, Greece^1

Department of Physics, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece^2

关键词: Accretion disks;    Accretion flow;    Dipolar magnetic fields;    Equipartition;    General Relativity;    Magnetized disks;    Plasma electrons;    Threshold-value;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/453/1/012003/pdf
DOI  :  10.1088/1742-6596/453/1/012003

来源: IOP

【 摘 要 】

The Cosmic Battery (CB) proposes that the innermost part of the accretion disk around an astrophysical black hole is threaded by a large scale dipolar magnetic field generated in situ due to the Poynting-Robertson radiation abberation effect on the plasma electrons. In that scenario, the return part of the field diffuses outward through the accretion disk. This is different from the scenario that the field originates at large distances and is carried inward by the accretion flow. In view of the importance of large scale magnetic fields in regulating the processes of accretion and outflows, we study the stability of the inner edge of a magnetized disk in general relativity when the distribution of the magnetic field is the one predicted by the Cosmic Battery. We found that as the field grows, the inner edge of the disk gradually moves outward. In a fast spinning black hole with a0.8M the inner edge moves back in towards the black hole horizon as the field grows beyond some threshold value. In all cases, the inner part of the disk undergoes a dramatic structural change as the field approaches equipartition.