A kinetic model of jet-corona coupling in accreting black holes

¹ Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
² IRAP, Université de Toulouse, CNRS, CNES, UPS, 14 Avenue Edouard Belin, 31400 Toulouse, France
³ Department of Astrophysical Sciences, Peyton Hall, Princeton University, Princeton, NJ, 08544 USA

^⋆ Corresponding author: john.mehlhaff@univ-grenoble-alpes.fr

Received: 20 December 2024
Accepted: 13 July 2025

Abstract

Context. Black hole (BH) accretion disks are often thought to be coupled to ultramagnetized and tenuous plasma coronae close to their central BHs. In this situation, the coronal magnetic field can exchange energy between the disk and the BH, power X-ray emission, and lead to jetted outflows. Up until now, the global coronal physics of BH accretion has only been studied using fluid modeling.

Aims. We construct the first global model of a BH feeding on a zero-net-flux accretion disk corona based on kinetic plasma physics. This permits a self-consistent study of how collisionless relativistic magnetic reconnection may regulate the putative coronal dynamics.

Methods. We present global, axisymmetric, general relativistic particle-in-cell simulation of a BH accreting a series of magnetic loops from a razor-thin accretion disk modeled as a boundary. We target the jet-launching regime with loops much larger than the BH. We track the flow of Poynting flux, both globally and along specific field-line bundles, and ray-trace high-energy synchrotron light curves.

Results. Reconnection on field lines coupling the BH to the disk dominates the synchrotron output, regulates the flux threading the BH, and ultimately untethers magnetic loops from the disk, ejecting them via a magnetically striped Blandford-Znajek jet. The jet is initially Poynting-dominated, but reconnection operates at all radii, depleting the Poynting power logarithmically in radius.

Conclusions. Coronal emission and jet launch are linked through reconnection in our model. This link might explain coincident X-ray flaring and radio-jet ejections observed during hard-to-soft X-ray binary state transitions. It also suggests that striped jet launch could be heralded by a bright coronal counterpart. Our synchrotron signatures resemble variability observed from the peculiar changing-look active galactic nucleus, 1ES 1927+654, hinting that processes similar to our model may be at work in this context.