A de Vries 2000 Class. Quantum Grav. 17 123 doi:10.1088/0264-9381/17/1/309
A de Vries
Show affiliationsThe apparent shapes of various Kerr-Newman spacetimes are plotted. For this purpose the geometry of closed photon orbits is studied, forming a subset of the bifurcation set A 4 , well known in elementary catastrophe theory. One additional result is that the cosmic censorship hypothesis guarantees that the spacetime casts a shadow, whereas naked ring singularities enable the visibility of the `anti-world' of negative radii r through its interior. Moreover, the optical restrictions to the observability of the shadow of an astronomical black hole are inferred.
04.70.-s Physics of black holes
Issue 1 (7 January 2000)
Received 12 April 1999
A de Vries 2000 Class. Quantum Grav. 17 123
Ron Donagi et al 2000 Class. Quantum Grav. 17 1049
Piotr T Chrusciel 1999 Class. Quantum Grav. 16 689
Jorge L Cervantes-Cota 1999 Class. Quantum Grav. 16 3903
Peter Hübner 1999 Class. Quantum Grav. 16 2823
Piotr T Chrusciel 1998 Class. Quantum Grav. 15 3845
Matt Visser 1998 Class. Quantum Grav. 15 1767
Jürgen Ehlers 1997 Class. Quantum Grav. 14 A119
Damiano Anselmi 1997 Class. Quantum Grav. 14 2031
Chiang-Mei Chen et al 1996 Class. Quantum Grav. 13 701