Electron-positron cascade in magnetospheres of supermassive Kerr black holes and the origin of relativistic AGN jets

TL;DR

This paper investigates electron-positron pair cascades in the magnetospheres of supermassive Kerr black holes, exploring their role in AGN jet formation and highlighting the need for additional lepton sources to explain observed emissions.

Contribution

It provides detailed constraints on plasma cascade conditions in AGNs and discusses the insufficiency of cascades alone to account for jet emissions, proposing alternative lepton sources.

Findings

Cascades generate fewer pairs than needed for observed jet emissions.

Parameter constraints determine when AGNs can sustain efficient cascades.

Additional lepton sources are likely necessary for luminous jet production.

Abstract

The avalanche mechanism of plasma production in active galactic nuclei (AGNs) is detailed, and constraints on system parameters needed for efficient electron-positron pair cascades are explored. Whether an AGN falls within this favorable parameter range may explain the observed radio-loud versus radio-quiet dichotomy. On the other hand, this study shows that cascades generate orders of magnitude fewer pairs than is necessary to explain the synchrotron emission observed in luminous jets. This fact suggests the existence of either an alternative lepton source, namely pair production of photons from the hot accretion flows around AGN central black holes, or matter loading of the jets from the surrounding medium, or, most likely, both. The case of the radio galaxy 3C 120 is considered in detail.