Scientists have found what they describe as a missing link between the behaviour of the smallest and the biggest black holes.
Star-sized black holes often pulse X-rays as they pull gas into themselves and tear it apart.
Durham University researchers say they have now witnessed this same pulsing signature in the gargantuan black holes that reside at the cores of galaxies.
More: http://news.bbc.co.uk/2/hi/science/nature/7622692.stm