Physics of Pair Producing Gaps in Black Hole Magnetospheres

TL;DR

This paper uses time-dependent simulations to study pair production gaps in black hole magnetospheres, revealing intermittent gap activity that could explain observed high-energy phenomena and structural differences in black hole environments.

Contribution

It introduces self-consistent 1D PIC simulations including inverse Compton scattering to model gap dynamics in black hole magnetospheres, highlighting their potential observational signatures.

Findings

Gaps open quasi-periodically, producing pairs and gamma-rays.

Intermittent gap activity matches observed TeV flare timescales.

Gap electric fields may influence global magnetospheric structure.

Abstract

In some low-luminosity accreting supermassive black hole systems, the supply of plasma in the funnel region can be a problem. It is believed that a local region with unscreened electric field can exist in the black hole magnetosphere, accelerating particles and producing high energy gamma-rays that can create $e^{\pm}$ pairs. We carry out time-dependent self-consistent 1D PIC simulations of this process, including inverse Compton scattering and photon tracking. We find a highly time-dependent solution where a macroscopic gap opens quasi-periodically to create $e^{\pm}$ pairs and high energy radiation. If this gap is operating at the base of the jet in M87, we expect an intermittency on the order of a few $r_g/c$, which coincides with the time scale of the observed TeV flares from the same object. For Sagittarius A* the gap electric field can potentially grow to change the global magnetospheric structure, which may explain the lack of a radio jet at the center of our galaxy.