Earlier this year, astronomers were monitoring data from the Twicky Transient Facility, a sky survey at the Palomar Observatory in California. Then they spotted an unusual flash in a part of the sky where no such light had been observed the night before. Roughly calculated, the Flash appeared to give off more light than her 1,000 trillion Suns.
A team led by researchers from NASA, Caltech and others published the discovery in an astronomy newsletter, and the signal caught the attention of astronomers around the world, including scientists at MIT. Over the next few days, multiple telescopes will focus on the signal to collect more data across multiple wavelengths in the X-ray, ultraviolet, optical and radio bands, potentially revealing such vast amounts of light. I checked what it might be generating.
Now, astronomers at MIT and their collaborators have identified what they believe is the source of the signal. A study published today in Nature Astronomy reports that the signal, dubbed AT 2022cmc, likely originated from a jet of relativistic matter ejected from a supermassive black hole at nearly the speed of light. They believe the jet was the product of a black hole that suddenly began engulfing nearby stars, releasing large amounts of energy in the process.
Astronomers have observed other such “tidal disruption events,” or TDEs, in which a passing star is torn apart by the black hole’s tidal forces. AT 2022cmc is the brightest TDE ever discovered. The source is also the most distant TDE ever discovered, about 8.5 billion light years away, more than half the universe.
How could an event this far away appear brighter in our sky? It states that the signal appears brighter.The effect is “Doppler boost”, similar to the boosted sound of a passing siren.
AT 2022cmc is the fourth Doppler-enhanced TDE ever detected and the first event observed since 2011. It is also the first TDE detected by an optical all-sky survey.
As more powerful telescopes come into operation in the next few years, more TDEs will be revealed that may reveal how supermassive black holes grow and form the galaxies around them. prize.
“We know there is one supermassive black hole per galaxy, and they formed very quickly in the universe’s first million years. That tells us they feed very fast, though we don’t know how that feeding process works. So, sources like a TDE can actually be a really good probe for how that process happens,” says co-author Matteo Lucchini, a postdoc in MIT’s Kavli Institute for Astrophysics and Space Research.
Lucchini’s MIT co-authors include first author and research scientist Dheeraj “DJ” Pasham, postdoc Peter Kosec, assistant professor Erin Kara, senior research scientist Ronald Remillard, and collaborators at universities and research institutions around the world. includes persons.
After the initial discovery of AT 2022cmc, Pasham and Lucchini focused the signal with the Neutron Star Interior Composition Explorer (NICER), an X-ray telescope operating on the International Space Station.
Pasham recalls, “Things looked pretty normal the first three days. Then we looked at it with an X-ray telescope, and what we found was, the source was too bright.”
Bright flashes in the sky like this are usually gamma-ray bursts. This is the extreme X-ray radiation produced when massive stars collapse.
“This particular event was 100 times more powerful than the most powerful gamma-ray burst afterglow,” Pasham says. “It was something extraordinary.”
The team then collected observations from other X-ray, radio, optical and UV telescopes to track the signal’s activity over the next few weeks. The most striking feature they observed was the extreme luminosity of the signal in the X-ray regime. They found that the X-ray emissions from AT 2022cmc fluctuate rapidly by a factor of 500 in just a few weeks.
They theorize that such extreme X-ray activity must be driven by “extreme accretion episodes.” This is an event that produces a giant stirring disk, such as a tidal disturbance event that creates a vortex of debris when a battered star falls into a black star hole.
Indeed, the team found that his X-ray magnitude of AT 2022cmc is comparable to, though brighter than, that of his three previously discovered TDEs. These bright events created jets of material pointing directly at Earth. If the luminosity of AT 2022cmc is the result of a similar low-Earth jet, how fast would that jet need to travel to produce such a bright signal? We modeled the signal data and assumed that the event was a jet headed straight for Earth.
Lucchini says, “We found that the jet speed is 99.99 percent the speed of light.”
To generate such a powerful jet, the black hole must be in a very active phase. Pasham describes this as an “overfeeding frenzy.”
“It’s probably swallowing the star at the rate of half the mass of the sun per year. A lot of this tidal disruption happens early on, and we were able to catch this event right at the beginning, within one week of the black hole starting to feed on the star.”
Lucchini adds, “We expect many more of these TDEs in the future. Then we might be able to say, finally, how exactly black holes launch these extremely powerful jets.”
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