2006/04/30 by V. Bozza, F. De Luca, G. Scarpetta · 5 citations
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics and Cosmic Phenomena #Pulsars and Gravitational Waves Research #astro-ph #gr-qc
paper · pdf · doi:10.1103/physrevd.74.063001
published as Phys.Rev. D74 (2006) 063001 · 17 pages, 4 figures, one section added, to appear on Physical Review D
arxiv created 2006/08/03 · openalex publication_date 2006/09/05 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We generalize our previous work on gravitational lensing by a Kerr black hole in the strong deflection limit, removing the restriction to observers on the equatorial plane. Starting from the Schwarzschild solution and adding corrections up to the second order in the black hole spin, we perform a complete analytical study of the lens equation for relativistic images created by photons passing very close to a Kerr black hole. We find out that, to the lowest order, all observables (including shape and shift of the black hole shadow, caustic drift and size, images position and magnification) depend on the projection of the spin on a plane orthogonal to the line of sight. In order to break the degeneracy between the black hole spin and its inclination relative to the observer, it is necessary to push the expansion to higher orders. In terms of future very-long base line interferometry observations, this implies that very accurate measures are needed to determine these two parameters separately.