Permanent URL to this publication: http://dx.doi.org/10.5167/uzh-16760
Sereno, M; de Luca, F (2008). Primary caustics and critical points behind a Kerr black hole. Physical Review D, 78(2):023008.
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The primary optical caustic surface behind a Kerr black hole is a four-cusped tube displaced from the line of sight. We derive the caustic surface in the nearly asymptotic region far from the black hole through a Taylor expansion of the lightlike geodesics up to and including fourth-order terms in m/b and a/b, where m is the
black hole mass, a the spin and b the impact parameter. The corresponding critical locus in the observer’s sky is elliptical and a point-like source inside the caustics will be imaged as an Einstein cross. With regard to lensing
near critical points, a Kerr lens is analogous to a circular lens perturbed by a dipole and a quadrupole potential.
The caustic structure of the supermassive black hole in the Galactic center could be probed by lensing of low
mass X-ray binaries in the Galactic inner regions or by hot spots in the accretion disk.
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|Item Type:||Journal Article, refereed, original work|
|Communities & Collections:||07 Faculty of Science > Institute for Computational Science|
|Deposited On:||13 Mar 2009 10:22|
|Last Modified:||27 Nov 2013 19:34|
|Publisher:||American Physical Society|
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