We analytically compute the observational appearance of an isotropically emitting point source on a circular, equatorial orbit near the horizon of a rapidly spinning black hole. The primary image moves on a vertical line segment, in contrast to the primarily horizontal motion of the spinless case. Secondary images, also on the vertical line, display a rich caustic structure. If detected, this unique signature could serve as a 'smoking gun' for a high spin black hole in nature.
- Black hole physics
- Gravitational lensing: strong
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science