Unified understanding of Alfvénic superradiance and the Blandford-Znajek process in a force-free black hole magnetosphere
Unified understanding of Alfvénic superradiance and the Blandford-Znajek process in a force-free black hole magnetosphere
We investigate the extraction of energy from a Kerr black hole via Alfvén waves (i.e., Alfvénic superradiance) in a force-free magnetosphere, in which the plasma inertia effects are ignored. We analyze the Poynting flux generated by Alfvén waves that propagate toward the event horizon across the inner light surface, the causal boundary for the waves. We find the relationship between the energy flux associated with Alfvén waves and that of the Blandford-Znajek (BZ) process. That is, both mechanisms can be described within a unified formulation of the Poynting flux, where the BZ process can be regarded as the long wavelength limit of the Alfvénic superradiance, and depending on the wave's frequency, Alfvén waves enhance or suppress the Poynting flux in the BZ process. This unified framework for the BZ process and the Alfvénic superradiance would offer a valuable perspective for understanding the energy sources of high-energy astrophysical phenomena, such as relativistic jets.
Sousuke Noda、Masaaki Takahashi
天文学物理学
Sousuke Noda,Masaaki Takahashi.Unified understanding of Alfvénic superradiance and the Blandford-Znajek process in a force-free black hole magnetosphere[EB/OL].(2025-08-06)[2025-08-18].https://arxiv.org/abs/2508.04771.点此复制
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