Tim Naylor

The masses of black holes

(With Tariq Shahbaz, Greg Beekman and Phil Charles.) After the discovery of the first stellar-mass black-hole candidates it was clear that radial velocity studies of the secondary stars which orbited them could only yield lower limits to the masses of the black holes. Yet the masses of the black holes themselves are of great interest. First to show that they do actually exceed the minimum mass for a black hole (3 solar masses), securing them as a strong black-hole candidate, but second to understand the stellar evolution which led to them, and the physics of matter at nuclear and super-nuclear densities. I realised that we could adopt the elliposidal technique from classical astronomy, using the fact that the secondary star is distorted by the gravitational field of the black hole to measure the inclination of the binary, and hence measure the mass. In a series of papers we showed that the black holes are around 10 solar masses (Shahbaz, Naylor & Charles 1994; Shahbaz et al 1994; Beekman et al 1996; Beekman et al 1997).