Quasars are caused by the close encounter of two supermassive black holes, each with billions of solar masses and crammed into tight quarters at the center of a galaxy. (sciencemag.org)
Accordingly, the collapse of millions or billions of solar masses of interstellar gas under gravitational force into a large black hole would account for the enormous energy output of quasars and certain galactic systems. (britannica.com)
«The observations of extremely massive black holes in the very early Universe are somewhat surprising, since it is not straightforward to grow the mass of black hole from tens up to billions of solar masses in the limited time available,» Johansson said in a statement Tuesday. (ibtimes.com)