Washington: Astrophysicists have for the first time detected the oscillating signal that indicates the last gasps of a star falling victim to a previously dormant supermassive black hole.
Led by researchers at the University of Michigan, the team documented the event with the Suzaku and XMM-Newton orbiting X-ray telescopes. These instruments picked up semi-regular blips in the light from a numerically-named galaxy 3.9 billion light-years away in the northern constellation Draco the dragon.
The blips, scientifically known as “quasiperiodic oscillations,” occurred steadily every 200 seconds, but occasionally disappeared. Such signals have often been detected at smaller black holes and they’re believed to emanate from material about to be sucked in, explained Rubens Reis, an Einstein Postdoctoral Fellow at U-M and first author of a paper on the work.
“In order for the black hole to feed from a star that its gravity has broken apart, the remains of the star must form an accretion disk surrounding the black hole. The disk gets heated up and we can see emissions from the disk very close to the black hole in X-rays. As this matter is falling in, it gives a quasiperiodic wobble and that’s the signal we detected,” Reis explained.
Jon Miller, astronomy professor at U-M and a co-author of the paper added “You can think of it as hearing the star scream as it gets devoured, if you like.”
The researchers liken the signal to a sound because it repeats at a characteristic frequency, which they say would sound like an ultra-low D-sharp.
“Our discovery opens the possibility of studying orbits close to black holes that are very distant, and it could make it possible to study general relativity under extreme settings,” Miller said.
For Reis, the findings confirm the constancy of black hole physics.
“This is telling us that the same physical phenomenon we observe in stellar mass black holes is also observed in black holes a million times the mass of the Sun, and also for black holes that were previously asleep. It speaks to the invariant nature of physics, which I think is very beautiful,” Reis said.
Their discovery has been published in Science Express.