On October 12, 2020, telescopes captured an event in a galaxy 3 billion light years away from Earth, a bright glow that then went out. According to scientists, this could be a signal related to the birth of a black hole. “It’s really impressive,” says Deanne Coppejans, an astrophysicist at Northwestern University, United States, referring to the show called Camel.
Two years earlier, something similar happened elsewhere, “just” 200 million light years from here, in the constellation of Hercules. It was not known exactly, at that time, what would have originated the so-called AT2018cow – or simply Cow -, but the scientific community considered some hypotheses, such as the possibility of a star having been consumed by a black hole near it or a supernova having “failed” and been “swallowed” by a new devourer of matter to whom she gave birth.
Anyway, one thing was already certain: the observed transient phenomenon, a type of supernova explosion with its visible light shining and decreasing in days, might not be the last – and, if it were common in space, it was necessary to prepare to understand it better. Now said and done. “We were able to understand what it was a few days after it exploded,” says Daniel Perley, an astrophysicist at Liverpool John Moores University, UK. “We have a lot of data generated by the monitoring.”
Event suggests birth of black hole.Source: Reproduction
“It did, it didn’t, it ended up being”
A real race against time started right after detection. Four days after viewing the Camel, the team at the head of the survey used equipment in the Canary Islands and Hawaii to collect vital information about their properties and alerted other experts via a service called Astronomers Telegram. Then, two designations were given to the event: AT2020xnd, for the global catalog of transients, and ZTF20acigmel, for the Zwicky Transient Facility (where it “appeared”). “Xnd didn’t live up to what we expected,” Perley jokes.
In just two or three days, the scientists say, Camelo reached its maximum brightness, 100 times higher than that of any conventional supernova, and quickly began to disappear, maintaining, however, its heat. From the analysis of archives, it was discovered that this was the fourth phenomenon of the type about which we had news, which did not take away from it the merit of being the first monitored in real time. Each, in turn, had its peculiarities.
“The explosion itself and the type of zombie behavior after death are very similar, but the collision stage, which involves the material in the environment [gás e poeira próximos], showed some variation in the amount of elements scattered and in the speed at which the shock wave of the explosion hits bodies around these scenarios “, points out Anna Ho, an astrophysicist at the University of California at Berkeley, United States, who discovered one of them, the Koala .
Camel reached its maximum brightness, 100 times higher than that of any conventional supernova, in a few days.Source: Reproduction
In short, the second hypothesis cited, the “failed” supernova, is the most promising. It all starts when a massive star about 20 times the mass of our Sun reaches the end of its life and runs out of fuel. Its core then collapses, initiating a process that would normally result in a traditional supernova, in which the falling material would come back out, leaving a dense object behind.
In the case of Camel, Cow and Koala, something unusual happened at the time of the collapse of the nucleus, says Daniel. “What we say is that, instead of turning into a neutron star, the star collapsed directly into a black hole, and most of it fell into it.”
By devouring the outer layers, the new body began to rotate rapidly, producing powerful jets fired from the poles – and this would be the light that reached our planet.
Zwicky Transient Facility, where Camel was discovered.Source: Reproduction
Other ideas are on the table, but none has been as successful as this one. Fortunately, all will be able to pass tests, as the ability of scientists to collect radio and X-ray data, for example, has expanded greatly in just two years, commemorates Stephen Smartt, an astronomer at Queen’s University of Belfast, Northern Ireland, ” owner “of the Cow.
Thanks to advances in techniques, adds Anna Ho, the trend is for more phenomena like these to be detected. “Initially, we were just looking for events that lit up very quickly. Since then, we’ve learned that objects of this type also disappear at high speed.”
In addition, there is hope: “This is just an example that we only have to look at the sky to be faced with totally unexpected things”, concludes the researcher.