The light that traveled more than 8.5 billion years to reach us was the last moments of a dying star as it was swallowed by a black hole.
Two separate teams of scientists have determined that a mysterious ray that appeared in the sky in February 2022, named AT2022cmc, was the astrophysical jet that erupted from the supermassive black hole as the ripped star disappeared beyond the event horizon.
It’s very rare that we catch one of these meals while we do it, and the AT2022cmc is now the furthest we’ve ever seen it.
Both papers have been published in nature And the natural astronomy.
“The last time scientists detected one of these jets was more than a decade ago,” says astronomer Michael Coughlin of the University of Minnesota-Twin Cities in the US.
“From our data, we can estimate that relativistic jets are fired in only 1% of these devastating events, making AT2022cmc an extremely rare event. In fact, the bright flash from the event is among the brightest ever observed.”
There’s a lot going on in our wild world, and a lot of encounters and events—supernovae, fast radio bursts, stellar collisions, interactions in merging binaries, and black hole feedings—are unpredictable, spewing out temporary glows of light that streak across. Space widens, then fades away.
Only by closely observing large areas of the sky can we catch the light of these massive but fleeting cosmic events.
In February, such a flare caught fire at the Zwicky transient facility. Immediately, 20 more telescopes around the world and in space sprang into action, capturing a wealth of data on the sudden blaze over the days and weeks that followed.
From this wealth of information, a team of researchers—led by Coughlin and astronomer Igor Andreoni of the University of Maryland—determined that the event was caused by a tidal disturbance event. the culprit? A supermassive black hole is spinning at about 500 million times the mass of the sun, gobbling up stellar material at a whopping rate of half a sun per year.
Tidal disturbance events are severe. They occur when a star wanders very close to a black hole. Tidal forces in the gravitational field of this black hole are stretching the star, pulling on it so tightly that it is torn apart. The star’s debris then falls into the black hole.
This process produces a glow of light that fades over time, but we can detect it from Earth if it’s bright enough.
This is not what produced the light that astronomers saw from AT2022cmc.
“Things looked pretty normal for the first three days. Then we looked at it with an X-ray telescope, and what we found was that the source was very bright,” says astronomer Dheeraj Pasham of MIT, who led the second paper.
“This particular event was a hundred times more powerful than the strongest gamma ray afterglow. It was something extraordinary.”
The analysis revealed that the light was caused by an astrophysical jet. When a black hole is feeding, sometimes not all of the material orbiting it ends up outside the event horizon.
Magnetic field lines around the outside of the event horizon act as particle accelerators; Some of the material near the black hole is directed along these lines, being shot out from the black hole’s poles at speeds approaching the speed of light.
In the case of AT2022cmc, one of those jets is pointed directly at us and traveling at 99.99 percent of the speed of light. When matter is moving toward us at close to the speed of light, it appears brighter than it is because the motion produces a change in the frequency of the light’s wavelength. This effect is known as relativistic radiation, or Doppler enhancement because this change is known as the Doppler effect.
AT2022cmc is the fourth Doppler-enhanced tidal disturbance event ever detected.
Scientists expect that we can learn a lot from this dying light from more than half of the universe. For example, it is not known why jets are present in some tidal disturbance events and others not. The black hole’s rapid spin could be instrumental in the formation of jets.
Nor is it clear how supermassive black holes form and grow. Higher feeding rates, such as that shown by the AT2022cmc black hole, may help solve the mystery.
This event was also the first tidal disturbance event to be detected using a scan. The data sets collected will help astronomers identify more of them in the future.
“Astronomy is changing rapidly,” Andreone says.
More optical and infrared surveys across the sky are now active or will soon be online. Scientists can use AT2022cmc as a model for what to look for and find more disruptive events from distant black holes.
“This means that big data mining is an important tool to advance our knowledge of the universe more than ever before.”
Research published in nature And the natural astronomy.
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