First ever accurate discovery of the rotational speed of the super-fast supermassive black hole
Researchers have found that the supermassive black hole at the center of the spiral galaxy NGC 1365 is rotating at nearly the speed of light.
This finding has been published in the journal Nature.
This black hole is more than 2 million miles across i.e. more than eight times the distance from the Earth to the Moon. It is as massive as several million Suns. Astronomers found the rotational speed of the black hole with the help of new data from the Nuclear Spectroscopic Telescope Array, or NuSTAR, and the European Space Agency’s XMM-Newton X-ray satellites.
“This is the first time anyone has accurately measured the spin of a supermassive black hole,” said lead author Guido Risaliti of the Harvard-Smithsonian Center for Astrophysics (CfA) and INAF – Arcetri Observatory.
Astronomers measured the X-rays from the center of the NGC 1365 to determine the location of the inner edge of the accretion disk. This innermost edge of the orbit depends on the spin of the black hole. The disk material comes closer to the black hole before being sucked in by it.
The information about the rotation of the black hole is important to know the mass and spin that could help in determining almost everything about black hole. Moreover, the spin of the black hole helps in studying its past and the evolution of the host galaxy.
“The black hole’s spin is a memory, a record, of the past history of the galaxy as a whole,” explained lead author Guido Risaliti of the Harvard-Smithsonian Center for Astrophysics (CfA) and INAF – Arcetri Observatory.
“The energy released by a growing supermassive black hole can be so powerful that it disrupts the normal growth of the host galaxy,” Christopher Reynolds of the University of Maryland, wrote in an article in Nature. “In extreme cases, (it) can terminate all subsequent growth of the galaxy.”
If the black hole pulls matter from all directions and grow randomly, its spin would be slow and the spinning speed of the black hole in NGC 1365 is maximum possible, it means that black hole grew with “ordered accretion” rather than the random events of pulling matter.
The study of the supermassive black hole will also help the scientists to work on the Einstein’s theory of general relativity in extreme conditions.
Reference:
Risaliti, G., Harrison, F., Madsen, K., Walton, D., Boggs, S., Christensen, F., Craig, W., Grefenstette, B., Hailey, C., Nardini, E., Stern, D., & Zhang, W. (2013). A rapidly spinning supermassive black hole at the centre of NGC 1365 Nature, 494 (7438), 449-451 DOI: 10.1038/nature11938
