"NICER has allowed us to measure light echoes closer to a stellar-mass black hole than ever before", said first author Erin Kara.
"That's not super fast - there are other black holes with spins estimated to be near 99 percent the speed of light", Pasham says. Astronomers estimate that any given galaxy's central black hole should produce a TDE every 10,000 to 100,000 years or so, which translates into tens of events per year with current survey capabilities.
Pasham and his colleagues thought that if they could see such regular flashes very close to a black hole that had undergone a recent tidal disruption event, these signals could give them an idea of how fast the black hole was spinning. "Does the disk move in and take over, or does the corona change and dissipate in some way?" Above that, you have the corona: an extremely energetic region of subatomic particles.
But why the corona contracted in such a way remains a mystery. The team came up with various scenarios, but the one that seems the most likely to generate such a strong, regular X-ray flare involves not just a black hole shredding a passing star, but also a smaller type of star, known as a white dwarf, orbiting close to the black hole. On November 22, 2014, astronomers discovered a supermassive black hole at the center of a galaxy that lies 300 million light-years from Earth.
One method used to chart those changes is called X-ray reverberation mapping, which uses X-ray reflections in much the same way sonar uses sound waves to map undersea terrain.
"It is very hard, the Spin of a Black hole limit, as the Spin effects occur only very close to the hole itself, where the gravity is extremely strong and it is hard to get a clear view", explains Pasham, in a communication to the European space Agency Esa.
"How does a black hole transition from being dominated by a corona to its disk?" The black hole was a buzz saw, spinning fast enough to stretch the star into a rotating ring around the black hole's event horizon, the point beyond which not even light can escape. "The corona is still pretty mysterious, and we still have a loose understanding of what it is. But now we have evidence that what is evolving in the system is the structure of the corona itself", he added. Researchers think that the dwarf's gravity pulled in the bright stellar remnants, creating a halo of X-rays around it. Time runs slower in stronger gravitational fields and at higher velocities, as stated in Einstein's theory of relativity.
The X-ray pulses were emitted by a dying star as it was sucked into the black hole - like its final screams being heard across the Universe. This Spin is in addition to the mass, from the effect of gravity on other celestial bodies to derive the most important property of Black holes, which, however, is not easy to determine. If the decreased lag time was caused by the inner edge of the disk moving even further inward, then the iron K line would have stretched even more. He explained that these tidal disruption events occur every thousand to 10 thousand years per galaxy, so they hope that they can one day measure several hundreds of these events per year to get a general picture about black hole's properties. "We've seen four similar events in NICER's first year, and it's remarkable".
NICER is an Astrophysics Mission of Opportunity within NASA's Explorer program, which provides frequent flight opportunities for world-class scientific investigations from space utilizing innovative, streamlined and efficient management approaches within the heliophysics and astrophysics science areas. "It feels like we're on the edge of a huge breakthrough in X-ray astronomy".