Measuring The Spin Of A Supermassive Black Hole…
….Using wobbling stellar material. The results offer a new way to probe supermassive black holes and their evolution across the universe.
Astronomers at MIT, NASA, and elsewhere have a new way to measure how fast a black hole spins, by using the wobbly aftermath from its stellar feasting.
The method takes advantage of a black hole tidal disruption event — a blazingly bright moment when a black hole exerts tides on a passing star and rips it to shreds. As the star is disrupted by the black hole’s immense tidal forces, half of the star is blown away, while the other half is flung around the black hole, generating an intensely hot accretion disk of rotating stellar material.
The MIT-led team has shown that the wobble of the newly created accretion disk is key to working out the central black hole’s inherent spin.
The study’s lead author, MIT Research Scientist Dheeraj “DJ” Pasham, says the new method could be used to gauge the spins of hundreds of black holes in the local universe in the coming years. If scientists can survey the spins of many nearby black holes, they can start to understand how the gravitational giants evolved over the history of the universe.
“By studying several systems in the coming years with this method, astronomers can estimate the overall distribution of black hole spins and understand the longstanding question of how they evolve over time,” says Pasham, who is a member of MIT’s Kavli Institute for Astrophysics and Space Research.
The study’s co-authors include collaborators from a number of institutions, including NASA, Masaryk University in the Czech Republic, the University of Leeds, the University of Syracuse, Tel Aviv University, the Polish Academy of Sciences, and elsewhere.