More than a thousand cosmic explosions detected by mysterious repetitive fast radio bursts

Using China’s Five-hundred-meter Aperture Spherical Radio Telescope, or FAST, researchers detected 1,652 bursts over the course of 47 days between August 29 and October 29, 2019. This is the largest set of fastest radio burst events ever recorded.

A study detailing these findings published Wednesday in the journal Nature.

Fast radio bursts, or FRBs, are millisecond-long emissions of radio waves into space, and astronomers have been able to trace some radio bursts back to their home galaxies. Scientists have not yet ascertained the actual cause of the glow. But small explosions can produce a year’s worth of our Sun’s total energy output.

Individual radio bursts are emitted once and do not repeat. But repeated fast radio bursts sometimes emit short, energetic radio waves. FRB 121102 is known as a repeat rapid radio burst since 2016.

Another mysterious radio explosion in space is repeating a pattern.  It happens every 157 days

During testing of the FAST telescope, as it was being turned on, researchers observed that FRB 121102 was frequently flaring with varying cadence and sending out radio signals. A total of 122 bursts were recorded during peak hours, making it the highest rate of any rapid radio burst ever. There were 1,652 individual eruptions in a total of 59.5 hours spread over 47 days.

“This was the first time that an FRB source had been studied in such detail,” said study co-author Bing Zhang, an astrophysicist and distinguished professor at the University of Nevada, Las Vegas, in a statement. “The large burst set helped our team look like never before on the specific energy and energy distribution of the FRB, shedding new light on the engines that power these mysterious phenomena.”

Study co-author Wang Pei, an assistant professor at the National Astronomical Observatories of the Chinese Academy of Sciences, said in a statement, the energy of the signals “severely constrains the possibility that FRB 121102 comes from an isolated compact object.”

this illustration a "River"  The number of bursts from the Milky Way as recorded by the FAST telescope.  Burst count and energy shown in histogram, painting "a vast land"  by Wang Zimeng of the Song Dynasty.

While some support the idea that aliens may be the source of these explosions, scientists are leaning toward black holes or hyper-magnetized neutron stars called magnetars.

Magnetars are dense stars, about the size of a city like Chicago or Atlanta, that have the strongest magnetic fields found in the universe. Scientists believe that the explosions may result from the magnetic field of magnetars.

FRB 121102 Was The first repeated rapid radio bursts to trace back to their source associated with a small dwarf galaxy more than 3 billion light-years away in 2017. Researchers also detected a pattern within the eruption in 2020. During this cyclical pattern, radio bursts are emitted during a 90-day window, followed by a silent period of 67 days. This pattern repeats every 157 days.

Previous observations have shown that usually when they do repeat, it is sporadic or in a group.

With this new impressive set of activity of FRB 121102, researchers can better understand the energy associated with these flashes. This could help scientists learn more about the possible source of the fast radio bursts.

The rapid radio bursts were only discovered in 2007, after it was discovered that some of them may repeat in 2016. Now, researchers know they may have patterns as well.

This illustration shows the FAST catching the actual pulse from FRB 121102.
NS Commons Radio Astronomy Fast Survey helped discover six new rapid radio bursts, including a repeat similar to FRB 121102.

Lead study author Li Di, a professor at the National Astronomical Observatories of the Chinese Academy of Sciences, said in a statement: “As the world’s largest antenna, FAST’s sensitivity proves well suited to reveal the complexities of cosmic travellers, including FRBs. “

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