2017/10/31 by Samuel E. Gralla, Alexandru Lupsasca, Andrew Strominger · 5 citations
Physics and Astronomy · #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Cosmic Phenomena #Black hole (networking) #Caustic (mathematics) #Event horizon #Geometry #Horizon #Line (geometry) #Physics #Pulsars and Gravitational Waves Research #Signature (topology) #Spin (aerodynamics) #Spinning #Telescope #astro-ph.HE #gr-qc #hep-th
paper · pdf · doi:10.1093/mnras/sty039
published as Mon. Notices Royal Astron. Soc. 475 (3), 3829-3853 (2018) · 36 pages, 6 figures. v2: added a figure and improved section 4.1, matches published version. Related videos available at https://youtu.be/ZRfTj5JKPkA and https://youtu.be/K0jEa0Q9NJA
openalex publication_date 2018/01/07 · arxiv created 2018/04/02 · arxiv updated 2018/04/04 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
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.