Hotspot Images from Magnetic Reconnection Processes in the plunging Region of a Kerr Black Hole

Employing the hotspot imaging technique, this work investigates the plasma motion trajectories prior to and following the Comisso-Asenjo mechanism within the plunging region. After a concise overview of the magnetic reconnection process in the plunging region of a Kerr black hole, we present the hotspot model and the associated imaging methodology. Through numerical simulations, we separately examine the hotspot images in the plunging region under three conditions: no magnetic reconnection, with magnetic reconnection, and when the escape condition fails. These outcomes are also contrasted with hotspot images in the circular orbit zone. Our findings reveal that for hotspot images without magnetic reconnection, when the plasma follows plunging orbits, the flare strength gradually declines; conversely, for circular orbits, the flare strength remains approximately constant. Additionally, we observe that the signal indicative of energy extraction is less conspicuous in the plunging region compared to the circular orbit region. We also discuss the astrometric counterpart of the signal and the caveats of the model.