In February, astronomers at the Zwicky Transient Facility in California saw a bright flash of light. The vivid flare, which was later named AT 2022cmc, prompted endless questions.
While these flashes aren’t exactly new to scientists (astronomers have seen plenty of these flashes from deep space before), this particular one was in a league of its own. Emanating from about 8.5 billion light-years away, it appeared to emit more light than 1,000 trillion suns combined. The human mind can barely comprehend that amount, let alone that amount of… alone.
Since the spectacular discovery of this brightness, scientists around the world began trying to decode where, why and even how the dazzling event could have occurred. And a pair of papers published Wednesday in the journals Nature and Nature Astronomy conclude that Zwicky picked up the signal from an extremely unique “tidal disruption event,” or TDE.
In other words, the team behind these studies believe that the flash came from a jet of matter that was spilling out from inside a supermassive black hole, traveling at supersonic speeds and pointing straight at the our planet
“We found that the speed of the jet is 99.99% of the speed of light,” said Matteo Lucchini, a researcher at MIT’s Kavli Institute for Astrophysics and Space Research and co-author of the study published in Nature Astronomy, in a statement.
When black hole pioneer John Wheeler presented the idea of the TDE beam combination in 1971, he described it as “a tube of toothpaste held tight in the middle,” leading him to “extract matter through both extremes”. Only about 1% of TDEs produce such superfast or relativistic jets of plasma and radiation that erupt from their two poles.
This jet, if the team is correct about its existence, would represent the most distant tidal disruption event ever detected. But what catches the most attention is its brightness. This is because the brighter the object, the easier it is to gather information from it.
A total of 21 telescopes around the world gathered data observing the jet across a wide range of light types, from radio waves to high-energy gamma rays. All of this information was then compared to data from known cosmic events ranging from neutron stars to kilonovae, but the only possibility that provided a solid match was a projected TDE pointing directly at us.
To that end, researchers believe it shows up as an unnatural glow from our point of view on Earth for two reasons.
First, the jet’s black hole habitation is likely devouring a nearby star, releasing a substantial amount of energy and emitting a ton of light during its party. As MIT study co-author Dheeraj “DJ” Pasham says, the jet is extremely active and in a “hyper-feeding frenzy.”
“The star is probably being swallowed up at a rate of half the mass of the sun per year,” Pasham said in a statement. “Much of this tidal disruption occurs early on, and we were able to capture this event early on, within a week of the black hole starting to feed on the star.”
But the second, and the most fascinating, in our opinion, is due to an effect called “Doppler boost”.
What is the Doppler shift?
Basically, the Doppler effect refers to how sound waves, light waves, and any other type of wave change as the thing making those waves travels toward or away from you.
Think about what happens when a car blasting music drives past your house. As it gets further and further away, the sound not only becomes less pronounced, but often changes pitch. This is because sound waves are stretched, causing your brain to recognize them as a lower pitch.
The Doppler effect also happens with light waves, often referred to by astronomers as redshift when talking about bright galaxies and stars moving away from our planet.
Here’s an illustration that shows what redshifting basically does to light coming from galaxies moving away from Earth.
NASA/JPL-Caltech//R. Hurt (Caltech-IPAC)
As these elements move further apart, the light waves they emit spread out, going from tighter blue to more relaxed ones. Finally, they even tread infrared waters, invisible to the human eye and standard optical machines, which is why NASA’s James Webb Space Telescope is so important. It can capture those super-stretched wavelengths present in the dark and deep universe.
But in the case of AT 2022cmc’s relativistic jet, the light is moving toward us, so it doesn’t get redder or softer with distance. It becomes more and more luminescent as its photons approach our telescopes, further enhanced by the fact that they scatter with enough vigor to nearly match the speed of light.
“Because the relativistic jet is pointed at us, it makes the event much brighter than it would otherwise appear and visible over a wider range of the electromagnetic spectrum,” said Giorgos Leloudas, an astronomer at DTU Space in Denmark and co-author of the study. study in nature
Abnormally bright bursts of light like this usually come from what are known as gamma-ray bursts. Gamma-ray bursts are also magnificent jets, although they are formed by X-ray emissions spewed from massive stars as their stellar bodies collapse. Because of their bright nature, these phenomena tend to populate the astronomy hall of fame. Last month, in fact, scientists were stunned by a powerful burst of gamma rays coming from about 2.4 billion light-years away in the universe. It’s literally called BOAT, the brightest of all time.
This sequence constructed from data from the Fermi Large Area Telescope reveals the sky in gamma rays centered on the location of GRB221009A, or BOAT. In total, they represent more than 10 hours of observations.
NASA/DOE/Fermi LAT collaboration
But AT 2022cmc, after further speculation, was definitely not a gamma-ray burst.
“This particular event was 100 times more powerful than the most powerful gamma-ray flare,” Pasham said. “It was something extraordinary.”
Lo and behold, after weeks of data mining and pulling out all the astronomical observational stops with X-ray, radio, optical and UV telescopes, the team concluded that AT 2022cmc must have come from the magnetic debris eddy of a black hole It must be a tidal disruption event, pigmented by the Doppler effect. If so, this would make it the fourth Doppler-enhanced TDE to be found and the first overall Doppler-enhanced event seen since 2011. It is also the first TDE to be found using an optical survey of the sky.
Scientists were also able to use the full spectrum of observations of AT 2022cmc to help determine its temperature and distance.
“Our spectrum told us the source was hot – about 30,000 degrees, which is typical of a TDE,” said Matt Nicholl, associate professor at the University of Birmingham. “But we also saw some absorption of light by the galaxy where this event occurred. These absorption lines were greatly shifted to redder wavelengths, which told us that this galaxy was very farther than we expected.”
Amazingly, the center of this distant galaxy is not yet visible because it is blotted out by the brightness of AT 2022cmc, but when it finally fades, the source galaxy may be observable with the James Webb telescope.
In the meantime, researchers will continue to scan the skies for the exotic and little-known TDE.
“We expect many more of these TDEs in the future,” Lucchini said. “Then we could finally tell how exactly black holes launch these extremely powerful jets.”