An observational signature for extremal black holes
Abstract
We consider scalar perturbations of the Reissner--Nordström family and the Kerr family. We derive a characteristic expression of the radiation field, at any given unit solid angle of future null infinity, and numerically show that its amplitude gets excited only in the extremal case. Our work, therefore, identifies an observational signature for extremal black holes. Moreover, we show that the source of the excitation is the extremal horizon instability and its magnitude is exactly equal to the conserved horizon charge.
- Publication:
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arXiv e-prints
- Pub Date:
- July 2023
- DOI:
- 10.48550/arXiv.2307.03963
- arXiv:
- arXiv:2307.03963
- Bibcode:
- 2023arXiv230703963A
- Keywords:
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- General Relativity and Quantum Cosmology;
- High Energy Physics - Theory;
- Mathematical Physics
- E-Print:
- 8 pages, 5 figures