Radiative Cooling Effects on Plasmoid Formation in Black Hole Accretion Flows with Multiple Magnetic Loops

Abstract

We investigate the influence of radiative cooling on plasmoid formation in black hole accretion flows using 2D and 3D two-temperature GRMHD simulations with multi-loop magnetic fields. Our results show that radiative cooling suppresses the transition to a MAD state by reducing magnetic flux accumulation near the horizon, modifies the disk structure via lower electron temperatures and increased equatorial density, and alters reconnection properties:compressing current sheets, shortening plasmoid lifetimes, and increasing their frequency. We also find enhanced negative energy-at-infinity density in plasmoids near the ergosphere. These findings indicate that radiative cooling critically shapes both large scale accretion dynamics and small-scale reconnection phenomena, potentially modulating black hole energy extraction through reconnection-driven Penrose processes.