Once considered rare and exotic objects, black holes are now known to exist throughout the universe, with the largest and most massive found at the centers of the largest galaxies. These “ultra-massive” black holes have been shown to have masses upwards of one billion times that of our own Sun. Now, Priyamvada Natarajan, an associate professor of astronomy and physics at Yale University and a fellow at the Radcliffe Institute for Advanced Study, and Ezequiel Treister, a postdoctoral fellow at the University of Hawaii, have shown that even the biggest of these gravitational monsters can’t keep growing forever. Instead, they appear to curb their own growth – once they accumulate about 10 billion times the mass of the Sun.
http://opa.yale.edu/news/article.aspx?id=5984&s=t