Astronomers have used a new method on data gathered by the Chandra X-ray Observatory and the Karl G Jansky Very Large Array (VLA) of the US National Science Foundation to precisely measure the spin of the supermassive black hole lurking within the core of the Milky Way Galaxy, bearing the designation of Sagittarius A* or Sgr A*. The researchers based their study on archival data, which is data from previous observations that was not conducted specifically for the purposes of the new study. Sgr A* is located at a distance of about 26,000 lightyears, at the centre of the Milky Way. The researchers measured the spin of the black hole by carefully tracking material moving towards and away from the black hole.
The researchers were able to determine that Sgr A* is spinning at about 60 per cent of the maximum possible value, which is a hard limit of the speed of light. The research settles discrepancies in previous observations, which ranged from the central supermassive black hole not spinning at all, to spinning at close to the maximum possible speed. The researchers have also found that the central supermassive black hole is squashing down spacetime itself, distorting and flattening the reality around itself. The black hole has been relatively quiescent in recent millennia, but may become more active in the future.
A paper describing the findings has been published in The Monthly Notices of the Royal Astronomical Society. Lead author of the study, Ruth Daly says, “Our work may help settle the question of how fast our galaxy’s supermassive black hole is spinning. Our results indicate that Sgr A* is spinning very rapidly, which is interesting and has far reaching implications.” The behaviour and temperment of the galaxy’s central supermassive black hole can have a major influence on the processes at work within the galaxy, including the rate at which new stars are formed. The research suggests that in the future, the black hole may give an incredibly violent kick to the surrounding matter, an event that may take place within our lifetimes, or millions of years into the future.