The fast radio burst acts like a beating heart and may have originated from a dashing distant neutron star.

Rapid radio bursts – huge bursts in space that release a huge amount of energy in a short time – continue to intrigue astronomers. And that’s not so strange. Remarkable specimens are discovered every time. So now. Astronomers have come across an exceptionally long and strange radio signal that appears to flash with surprising regularity.

What are fast radio flashes?
Rapid radio flashes (also called Fast Radio Burst or simply called FRB) are unpredictable but very powerful pulses of radio radiation. Very concretely, it often concerns eruptions in which more energy is released in 1 millisecond than our sun generates in 80 years. The first fast radio burst was discovered in 2007. Since then, many more fast radio bursts have been found scattered across the universe. Most are located at great distances from Earth in galaxies billions of light years away. Only a few have been observed closer.

The newly discovered signal, dubbed FRB 20191221A, is an odd one out. Typically, fast radio bursts last a few milliseconds. But FRB 20191221A makes itself heard for no less than three seconds; that’s about 1000 times longer than the average fast radio burst.

Beating heart

Within this window, the team discovered eruptions that follow each other after 0.2 seconds in a distinct periodic pattern, similar to a beating heart. “This is unusual,” said study researcher Daniele Michilli. “Not only did the signal last very long — about three seconds — but we noticed periodic spikes that were remarkably accurate.” All of this makes FRB 20191221A the longest lasting fast radio burst with the clearest periodic pattern detected to date.

Source

Where does this signal come from? The strange radio burst appears to originate in a distant galaxy, several billion light-years away from Earth. Exactly what the source is remains a mystery, although astronomers suspect the signal comes from a pulsar or magnetar; two different types of neutron stars (extremely dense, rapidly spinning collapsed cores of giant stars). “There aren’t many objects in the universe that send out periodic signals,” Michilli says. “Examples from our own galaxy are pulsars and magnetars. These rotate and produce beams of radiation that resemble the light emitted from a lighthouse. We therefore believe that the newly discovered signal may have come from a magnetar or powerful pulsar.”

Comparison

When analyzing the eruption pattern of FRB 20191221A, the researchers found striking similarities with emissions from pulsars and magnetars from our own Milky Way galaxy. But they also encountered differences. The biggest difference is that FRB 20191221A appears to be more than a million times brighter. “From the properties of this new signal, we can conclude that there is a plasma cloud around the source that is extremely turbulent,” concludes Michilli.

More flashes

The researchers hope to detect more periodic flashes from the same source, which can then be used as an astrophysical clock. For example, the frequency of the eruptions could be used to measure the rate at which the universe is expanding. But not only that. In fact, capturing more outbursts could also help us learn more about the still-mysterious source and its character, as well as broaden our understanding of neutron stars in general.

“This detection raises the question of what is causing this strange signal; a signal that we have never seen before,” says Michilli. “It also raises the question of how we can use this signal to study the universe.” We may not even have to wait that long for the answers. Because future telescopes promise to detect thousands of fast radio bursts per month. There is a good chance that astronomers will also find many more similar periodic signals, which could potentially unravel many existing mysteries.