Astronomers caught a potent radio burst blasting at us from a dwarf galaxy 3 billion light-years away

Massive explosions emitted from outer space show up in astronomers' data as a rapid rush of radio waves. FRBs, or fast radio bursts, may transport as much energy in a single pulse as our sun does in a hundred years. However, because the bursts are frequently only a few thousandths of a second long, radio astronomers often lack the context needed to make sense of these stunning cosmic occurrences or pinpoint where the flashes originated. As a result, FRBs have long been regarded as one of astronomy's greatest mysteries.

Scientists don't have a lot of information regarding what produces these intense radio wave eruptions. According to certain theories, the explosions are caused by the collision of incredibly massive objects like as black holes or neutron stars. Others believe that FRBs are caused by the collapse of distant stars.

Now, astronomers are gathering the information they need to piece together the FRB puzzle–a recently discovered burst possesses two critical characteristics that might help astronomers obtain a better understanding of these mysterious explosions.

The FAST (Five-hundred-meter Aperture Spherical Radio Telescope) in Guizhou, China, made the most recent FRB discovery. This explosion, though, was more than simply a blip on the scientists' radar. Researchers were able to find it in follow-up studies at observatories all around the world because it repeats at regular intervals. FRB 20190520B is also linked to a continuous source of radio emissions between those bursts, according to a report published in the journal Nature on Wednesday. The source is located on the outskirts of a dwarf galaxy 3 billion light-years away from Earth.

Researchers have been looking for occurrences that reoccur in order to make sense of FRBs. “The key question for everybody is its origin story,” says Di Li, the study's principal author and the head scientist of the FAST telescope at the Chinese Academy of Sciences' National Astronomical Observatories. “We really want to know what kind of astronomical object or what kind of physics may produce such a bright thing.”  

Since their discovery in 2007, the great majority of FRBs identified by astronomers have been discrete, independent occurrences. Only around 5% of the more than 500 bursts that have been seen reoccur.

The majority of people who don't come back represent an additional hurdle for follow-up research. “Although they are very bright, they are a one-off event,” Li says. “By the time you dig it out of the data, it could be the next day or even the next month. And then you just cannot go back…you cannot catch this cosmic explosion in the act.”

A once-in-a-lifetime occurrence is exciting. However, it is via repetition that scholars begin to piece together patterns in order to gain a better understanding of occurrences.

That's why the newest FSB finding gives academics a chance to fit the pieces of this exploding puzzle together. Following one discovered in 2012, this is just the second time a repeated FSB has been observed with a persistent source of weaker radio waves between the pulses. Since then, numerous repeaters have been discovered, but none have been linked to a constant radio source, giving astronomers more texture to investigate.

“The first only poses more questions. It’s the second, and third, and fourth that help us get the answers to that question,” says Navin Sridhar, a Columbia University astrophysics PhD candidate who researches FRBs and runs simulations to figure out how they work. He was not a part of the new research. “These are an extremely new class of events, and every single additional source and data point is just golden.” 

Scientists are attempting to determine what engine is responsible for these intense explosions, as well as how many distinct things might generate FRBs. Part of that effort involves determining where the bursts originate in the universe, but researchers are also classifying the occurrences into distinct categories. They're now divided into two groups: repeaters and non-repeaters. The presence of persistent radio emission adds another layer of complexity.

“We can say confidently that [the FRB discovered in 2012] is not an outlier,” Sridhar adds, citing this recent finding. However, the parallel FRBs might indicate a separate type of explosions. “So we cannot really put all FRBs into one basket and say, ‘Okay, all FRBs behave this way.’ This indicates the birth of a new class of FRBs.” 

Li thinks that there might be another explanation. He speculates that these two repeaters are younger FRBs. The concept is based on what you may observe shortly after an explosion. The debris may not evaporate right away. It takes some time for the substance to spread out into the universe. If astronomers catch the bursts early enough, the thicker cloud of ejecta might be the source of the radio emissions that endure. According to Li, this would also explain why it's so active.

Although the current FRB discovery bears some similarities to the first recurring FRB discovered in 2012, Sridhar points out that they are not identical. He also claims that the hypothesis that these bursts are particularly youthful is based on assumptions about what causes them. It would make sense, he thinks, if a magnetar (a neutron star with a very strong magnetic field) were to blame. However, if the source was anything like a class of blackhole binaries that accrete matter from neighboring stars, the radio signal would be revealed–and it would become stronger with time.

“We really need to know what the environment of a FRB is in order to pin down the engine that is powering it,” Sridhar explains.

After all, radio wave explosions aren't uncommon. Scientists estimate that hundreds of FRBs measurable on Earth occur every day in the cosmos. However, academics are merely scratching the surface of comprehending this perplexing occurrence. FRBs aren't the only enigma in the universe.

“We live in this very dynamic universe,” Li explains. “We keep finding these weird, sometimes hard to understand, mysterious things. There are way more things in the universe that are unknown than what has already been known.”