Conversion of electromagnetic and gravitational waves by a charged black hole
| Autor: | Hadj, Mohamed Ould El, Dolan, Sam R. |
|---|---|
| Rok vydání: | 2021 |
| Předmět: | |
| Zdroj: | Phys. Rev. D 106, 044002 (2022) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevD.106.044002 |
| Popis: | In a strong electromagnetic field, gravitational waves are converted into electromagnetic waves of the same frequency, and vice versa. Here we calculate the scattering and conversion cross sections for a planar wave impinging upon a Reissner-Nordstr\"om black hole in vacuum, using the partial-wave expansion and numerical methods. We show that, at long wavelengths, the conversion cross section matches that computed by Feynman-diagram techniques. At short wavelengths, the essential features are captured by a geometric-optics approximation. We demonstrate that the converted flux can exceed the scattered flux at large scattering angles, for highly-charged black holes. In the short-wavelength regime, the conversion effect may be understood in terms of a phase that accumulates along a ray. We compute the scattering angle for which the converted and scattered fluxes are equal, as a function of charge-to-mass ratio. We show that this scattering angle approaches $90$ degrees in the extremal limit. Comment: 20 pages, 7 figures. Added a proof that the angle for half-conversion is 90 degrees in the extremal case Q=M |
| Databáze: | arXiv |
| Externí odkaz: |
|