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

TL;DR

This study uses hotspot imaging to analyze plasma motion in the plunging region of a Kerr black hole, revealing how magnetic reconnection affects flare intensity and energy extraction signals.

Contribution

It introduces a novel hotspot imaging method combined with numerical simulations to study plasma behavior in the plunging region of Kerr black holes, considering magnetic reconnection effects.

Findings

Hotspot images without magnetic reconnection show decreasing flare intensity for plunging orbits.

Circular orbit hotspots maintain nearly constant flare intensity.

Energy extraction signals are weaker in the plunging region compared to circular orbits.

Abstract

Using the hotspot imaging method, this paper investigates the motion trajectory of plasma in the plunging region before and after the Comisso-Asenjo mechanism. Following a brief review of the magnetic reconnection process in the plunging region of a Kerr black hole, we introduce the hotspot model and imaging method. Based on numerical simulations, we separately study the hotspot images in the plunging region without magnetic reconnection, with magnetic reconnection, and when the escape condition is not met. We also compare these with hotspot images in the circular orbit region. The results show that for hotspot images without magnetic reconnection, if the plasma follow plunging orbits, the flare intensity gradually decreases, whereas if they follow circular orbits, the flare intensity remains nearly constant. Additionally, we find that in the plunging region, the signal for energy extraction is weaker compared to that in the circular orbit region.