Astronomers Detect Hundreds of Powerful Cosmic Explosions in Mysterious Radio Burst

A team of astronomers from across the globe have spotted an extreme episode of cosmic explosions. The "river" explosions represent the largest series of Fast Radio Burst (FRB) events ever recorded, more than is documented in all existing publications, put together.

Over a period of just 47 days, the researchers observed 1,652 separate explosions from the Fast Radio Burst (FRB) 121102.

FRBs are short-lived bursts of radio waves first observed in 2007. The cosmic explosions that create FRBs last just one-thousandth of a second. Yet, in this incredibly short period, these explosions can release as much energy as the sun puts out in a year.

The explosions observed by the team, beginning on August 29, 2019, should allow other researchers to determine the energy of all FRBs. This could not just help astronomers pinpoint where these bursts of radio wave radiation are coming from, but also identify the processes that create them.

"This was the first time that one FRB source was studied in such great detail," University of Nevada researcher Bing Zhang, said in a press release. "The large burst set helped our team hone in like never before on the characteristic energy and energy distribution of FRBs, which sheds new light on the engine that powers these mysterious phenomena."

Bing Zhang is one of the authors of a Nature paper discussing the findings.

FRB 121102 was a good choice to study the nature of FRBs because it was the first of this type of event, astronomers found, that repeats itself. Its repeating nature meant that, over nearly 60 hours across 47 days, the team was able to discover that in its most active period FRB 121102 contained 122 explosions in one hour, the most seen in any FRB to date.

This FRB has been traced back to a dwarf galaxy 3 billion light-years from Earth, making it a rare FRB with a well-known location.

Scientists still don't know where most FRBs are coming from or what processes are driving them.

One of the most recent suggestions for the origins of these short, radio wave bursts are magnetars, neutron stars with incredibly powerful magnetic fields that rotate rapidly. But scientists can't agree on what aspect of magnetars could be causing FRBs.

Bing Zhang explains that certain theories say that FRBs could be coming directly from these objects' magnetic fields themselves. Another idea says that magnetars spin so fast, tiny bumps on their surface send shockwaves at the speed of light through surrounding material, and this causes FRBs.

Bing Zhang continues by saying that the study of FRB 121102 could spell that end for one of these ideas. Because the bursts of energy the team saw were so frequent the total energy they release is too great for FRBs to be caused by shockwaves in the material around magnetars.

To conduct their observations, the team used Five-hundred-meter Aperture Spherical Telescope (FAST) in China, a powerful radio telescope. Consisting of the world's largest antenna FAST has been frequently used to study FRBs, and the team expects that repeating events like FRB 121102 will be widely studied by the radio telescope in the future.

A River of Explosions
A painting of a river of bursts discovered by the FAST telescope. The finding could reveal where these powerful bursts come from and what causes them. The image mimics the painting "A Vast Land" by WANG Ximeng of the Song Dynasty. NAOC