Unified understanding of Alfvénic superradiance and the Blandford-Znajek process in a force-free black hole magnetosphere
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arXiv
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| Auteurs principaux: | , |
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| Format: | Preprint |
| Publié: |
2025
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| _version_ | 1866909726500978688 |
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| author | Noda, Sousuke Takahashi, Masaaki |
| author_facet | Noda, Sousuke Takahashi, Masaaki |
| contents | 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. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2508_04771 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Unified understanding of Alfvénic superradiance and the Blandford-Znajek process in a force-free black hole magnetosphere Noda, Sousuke Takahashi, Masaaki High Energy Astrophysical Phenomena General Relativity and Quantum Cosmology 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. |
| title | Unified understanding of Alfvénic superradiance and the Blandford-Znajek process in a force-free black hole magnetosphere |
| topic | High Energy Astrophysical Phenomena General Relativity and Quantum Cosmology |
| url | https://arxiv.org/abs/2508.04771 |