Supermassive black holes, like their smaller stellar counterparts, have the ability to spin, new research indicates. What's more, interaction between the rotating black hole and its surrounding magnetic field comprises an additional energy source never before documented. A new report detailing these findings appears in the current issue of the Monthly Notices of the Royal Astronomical Society.
Using the European Space Agency's XMM Newton satellite, Joern Wilms of Tuebingen University and colleagues studied emissions from the supermassive black hole MCG-6-30-15, located more than 100 million light-years from earth. Specifically, they investigated the x-ray spectrum of iron gas originating from the event horizon, the theoretical border of a black hole. According to the researchers, the energy output of the gas was too high to be explained solely by gravity. "The magnetic field lines are like a series of cable-like strands twisted and tightened around the black hole by intense gravity," Wilms explains. "Our results indicate the x-ray emissions from gas connected to the magnetic field lines are much stronger and much closer to the black hole than we expected."
In addition to providing the first example of a spinning supermassive black hole, the new finding may represent the first observational evidence of a theory proposed more than 25 years ago. The Blandford-Znajek theory postulates that magnetic fields can act as brakes to slow a rotating black holein which case energy lost from the black hole must be transferred to the surrounding region. In MCG6-30-15, the energy moves to the inner edge of the accretion disk, a ring of interstellar material swirling around the black hole that eventually falls back into it. The amount of energy in the black hole, provided by a constant stream of gas clouds and sucked-up stars, is staggering. Indeed, co-author Mitchell Begelman of the University of Colorado reports that "it would take roughly a billion years to release all the energy stored up in MCG6-30-15."