Measurement of the Kerr Spin Parameter by Observation of a Compact Object's Shadow
High Energy Astrophysical Phenomena
2009-08-05 v3 General Relativity and Quantum Cosmology
Abstract
A black hole casts a shadow as an optical appearance because of its strong gravitational field. We study how to determine the spin parameter and the inclination angle by observing the apparent shape of the shadow, which is distorted mainly by those two parameters. Defining some observables characterizing the apparent shape (its radius and distortion parameter), we find that the spin parameter and inclination angle of a Kerr black hole can be determined by the observation. This technique is also extended to the case of a Kerr naked singularity.
Keywords
Cite
@article{arxiv.0904.3575,
title = {Measurement of the Kerr Spin Parameter by Observation of a Compact Object's Shadow},
author = {Kenta Hioki and Kei-ichi Maeda},
journal= {arXiv preprint arXiv:0904.3575},
year = {2009}
}
Comments
9 pages, 11 figures; v2: references added, typos corrected; v3: accepted for publication in Physical Review D