412 citations · 3.1k across the 30 of their papers we have counts for
5 papers · 1 filter
Sgr A* and General Relativity
Tim Johannsen
General relativity has been widely tested in weak gravitational fields but still stands largely untested in the strong-field regime. According to the no-hair theorem, black holes i…
Magnetised Accretion Discs in Kerr Spacetimes II: Hot Spots
Federico García, Ignacio F. Ranea-Sandoval, Tim Johannsen
Context. Quasi-periodic variability has been observed in a number of X-ray binaries harboring black hole candidates. In general relativity, black holes are uniquely described by th…
X-ray Probes of Black Hole Accretion Disks for Testing the No-Hair Theorem
Tim Johannsen
The spins of a number of supermassive and stellar-mass black holes have been measured based on detections of thermal continuum emission and relativistically broadened iron lines in…
Photon Rings around Kerr and Kerr-like Black Holes
Tim Johannsen
Very-long baseline interferometric observations have resolved structure on scales of only a few Schwarzschild radii around the supermassive black holes at the centers of our Galaxy…
Regular Black Hole Metric with Three Constants of Motion
Tim Johannsen
According to the no-hair theorem, astrophysical black holes are uniquely characterized by their masses and spins and are described by the Kerr metric. Several parametric spacetimes…