A new type of space explosion reveals the birth of the black hole
In 2018, astronomers they were shocked to find a strange explosion in a galaxy 200 million light-years away. It was as short and clear as a normal supernova that had never been seen before. The event was given an official designation, AT2018cow, but soon had a more jovial nickname: Cow.
Short-lived events — known as transients — challenged the explanation. Some thought it might be a star scratched by a nearby black hole, but others opted for the “failed supernova” scenario, where a black hole literally eats a star from the inside. To be sure, they had to find more Cow-shaped events.
More than two years later, they got one.
Beginning on October 12, 2020, when they saw telescopes turning into something incredibly bright in a galaxy 3,000 billion light-years away, they then disappeared from view. Astronomers reported that it behaved almost equally to the cow a paper was published last week on the arXiv.org online prepress site to conclude that it should be the same type of episode. In keeping with tradition, the animals gave it their own inspired name: camel.
“It’s really exciting,” said Deanne Coppejans, an astrophysicist at Northwestern University. “Finding a new transient like AT2018cow shows that it’s not a complete curiosity. It’s a new type of transient we’re seeing.”
The cow was a complete surprise, and the astronomers weren’t sure for sure what they saw when they looked at it. Camel, on the other hand, was similar to the thief who spoils the new alarm system. “We realized we had started a few days ago,” said Daniel Perley, an astrophysicist at John Moores University in Liverpool who led the new research. “And we’ve got a lot of follow-up data.”
Four days later, the team used telescopes from the Canary Islands and Hawaii to obtain key data about its properties. Later put an alert to other astronomers in a service called the Astronomer’s Telegram.
Two nominations were made for the event. One, AT2020xnd, came from a global catalog of all transients, and the other, ZTF20acigmel, from the Zwicky Transient Facility, which was found in the telescope. The group changed the latter to the nickname “Camel”. “Xnd didn’t have the same ring,” Perley said.
Like his predecessor, Gamel became very bright in a short time, reaching its peak in two to three days. It grew 100 times brighter than ordinary supernova types. It then quickly darkened, a process that lasted more than a few days than weeks. “It disappears very quickly, and it stays warm while it’s disappearing,” Perley said.
Prior to this discovery, astronomers analyzed historical data to find two complementary Cow-shaped events. “Koala” and CSS161010, but the camel is the first to be seen in real time and has thus been studied in detail in the cow.
All four events have similar properties. They shine quickly and then turn off. They are also hot, which makes them look blue. But these “fast blue optical filters” are not the same.
“The explosion itself is similar to the behavior of zombie life,” said Anna Ho, an astrophysicist at the University of California, Berkeley, who discovered Koala and was a member of the Camel discovery team. The events appear to be like an explosion of a star colliding with nearby gas and dust. “But the area around the collision you’re watching shows an explosion that collides with the material. It shows some variation in the amount of material around it and the speed at which the shock wave passes through the material.”
This is the main idea at the moment failure supernova hypothesis. The process begins when a massive star about 20 times the mass of our sun reaches the end of its life and runs out of fuel. Then its core falls apart, which would normally be a regular supernova, where the falling material bounces off again, leaving behind a dense object called a neutron star.
In cases like Camel and Cow, “something unusual happens to fall at the core of the process,” Perley said. “What we are claiming is that instead of falling to a neutron star it fell directly into a black hole and most of the star fell into a black hole.”