Earth's nearest supermassive black hole came alive 200 years ago
Sagittarius A* (pronounced 'Sagittarius A star'), the supermassive black hole at the heart of the Milky Way, woke up only about 200 years ago, as per new findings from NASA's IXPE (Imaging X-ray Polarimetry Explorer) telescope. Located over 25,000 light-years from Earth, Sagittarius A* is our nearest supermassive black hole and its mass is estimated to be millions of times that of our Sun.
Why does this story matter?
Black holes are powerful cosmic objects, ripping apart anything that wanders in their vicinity. The enigmatic nature of black holes has evoked deep interest among astronomers for years. And when we are talking about a black bole which is the closest to us in our Milky Way galaxy, the curiosity grows manifold.
Star-forming regions at Milky Way's center were noticed shining brightly
Initially, researchers noticed that giant star-forming gaseous clouds present in the center of the Milky Way galaxy were shining more brightly in X-rays than expected. One plausible explanation for this behavior was that this X-ray signal did not originate from the gaseous regions itself, but was a result of reflection on these clouds after an X-ray outburst from the Sagittarius A* black hole.
Using the IXPE telescope, scientists have evidence for their theory
Scientists theorize that Sagittarius A* devoured cosmic material, letting out a bright flash of X-rays which was then reflected by the gas clouds which are lying close to the black hole. By using the IXPE telescope, the team has now discovered strong evidence in support of their theory and has also been able to estimate that the original flare occurred 200 years ago.
Sagittarius A* devours any cosmic material wandering close to it
As a black hole rips apart the material, it expels X-rays and the debris falls right into the black hole. What cosmic object did the Sagittarius A* tear apart? That's something we do not know. Several stars and gaseous clouds wander dangerously close to Sagittarius A and any of them may have been caught by the monster black hole.
NASA's IXPE can measure the polarization of X-rays
NASA's IXPE telescope can measure the polarization of X-rays which occurs as black holes devour cosmic material. Polarization refers to the oscillation of light waves in a particular direction, which can reveal information about how the light has been produced and reflected, says space.com. Using IXPE, researchers found the polarization angle of the X-ray signals points to the direction of Sagittarius A*.
'The polarization angle acts like a compass'
"The polarization angle acts like a compass, pointing us toward the mysterious, long-gone source of illumination," said Riccardo Ferrazzoli, an astrophysicist at the Italian National Institute of Astrophysics in Rome. "And what lies in that direction? None other than Sagittarius A*."
Researchers want to dig deeper in future studies
Currently, Sagittarius A* is dormant. In further investigations, researchers want to dig deeper to find out which physical processes would be able to wake up the now-inactive black hole again. The team hopes future studies would help improve estimations of the intensity and timing of the X-ray outburst and could help determine the three-dimensional distribution of the huge molecular clouds near the black hole.
