El Mellah I, Cerutti B, Crinquand B, Parfrey K
Univ. Grenoble Alpes, CNRS, IPAG.
School of Mathematics, Trinity College Dublin.
Proc Int Astron Union. 2023 Jan 23;16(Suppl 362):184-189. doi: 10.1017/S1743921322001715.
The hot accretion flow around Kerr black holes is strongly magnetized. Magnetic field loops sustained by a surrounding accretion disk can close within the event horizon. We performed particle-in-cell simulations in Kerr metric to capture the dynamics of the electromagnetic field and of the ambient collisionless plasma in this coupled configuration. We find that a hybrid magnetic topology develops with a closed magnetosphere co-existing with open field lines threading the horizon reminiscent of the Blandford-Znajek solution. Further in the disk, highly inclined open magnetic field lines can launch a magnetically-driven wind. While the plasma is essentially force-free, a current sheet forms above the disk where magnetic reconnection produces macroscopic plasmoids and accelerates particles up to relativistic Lorentz factors. A highly dynamic Y-point forms on the furthest closed magnetic field line, with episodic reconnection events responsible for transient synchrotron emission and coronal heating.
克尔黑洞周围的热吸积流具有很强的磁化作用。由周围吸积盘维持的磁场环可以在事件视界内闭合。我们在克尔度规下进行了粒子模拟，以捕捉这种耦合构型中电磁场和周围无碰撞等离子体的动力学。我们发现，一种混合磁拓扑结构发展起来，其中封闭的磁层与穿过视界的开放磁力线共存，这让人想起布兰德福德-兹纳耶克解。在盘的更远处，高度倾斜的开放磁力线可以引发磁驱动风。虽然等离子体基本上是无力的，但在盘上方会形成一个电流片，磁重联在那里产生宏观等离子体，并将粒子加速到相对论洛伦兹因子。在最远的封闭磁力线上形成一个高度动态的Y点，间歇性的重联事件导致瞬态同步辐射发射和日冕加热。
