One of the leading theoretical astrophysicists of his generation
Donald Lynden-Bell, who has died aged 82, was one of the leading theoretical astrophysicists of his generation. He proposed in 1969 that quasars are powered by supermassive black holes and that most large galaxies, including our own, would host a dead quasar in their nucleus. He was a brilliant dynamicist, inventing the concept of “violent relaxation” in stellar systems, but he was also interested in what could be learned from observational mapping of our galaxy and its surroundings.
Quasars, short for quasi-stellar radio sources, had been found during optical follow-up of radio surveys. In 1963 Maarten Schmidt had found that the quasar 3C273 had what was for the time a high red shift, indicating that it had a huge luminosity, and others soon followed. For a while, there was controversy about whether the red shifts were cosmological.