The fast radio burst acts like a beating heart and may have originated from a distant neutron star.
Fast radio bursts – colossal explosions in space that release an enormous amount of energy in a short time – continue to intrigue astronomers. This is not very strange. Great specimens are discovered every time. And now. Astronomers have come across an exceptionally long and strange radio signal that appears to flash with surprising regularity.
What are fast radio flashes?
Radio fast flashes (also called Impulse Radio or simply called FRB) unpredictable but very powerful radioactive pulses. Very concretely, it often has to do with eruptions in which more energy is released in 1 millisecond than our Sun has generated in 80 years. The first fast radio burst was discovered in 2007. Since then, more and more fast radio bursts have been found scattered throughout the universe. Most of them are located at great distances from Earth in galaxies billions of light years away. Only a few were observed up close.
The newly discovered signal, called FRB 20191221A, is a strange one. Fast radio bursts usually last a few milliseconds. But FRB 20191221A makes itself audible for at least three seconds; This is about 1,000 times longer than the average fast radio burst.
Within this window, the team detected explosions following each other 0.2 seconds later in a distinct periodic pattern, similar to a beating heart. “This is unusual,” said researcher Danielle Micheli. “The signal didn’t last very long – about three seconds – but we did notice periodic spikes that were remarkably accurate.” All this makes FRB 20191221A the longest running fast radio burst with the clearest periodic pattern detected to date.
Where does this signal come from? The strange radio explosion appears to have originated in a distant galaxy, several billion light years from Earth. The exact source remains a mystery, although astronomers suspect the signal comes from a pulsar or magnetar. Two different types of neutron stars (the cores of very dense, fast-spinning giant stars). “There aren’t many things in the universe that send out periodic signals,” says Micheli. Examples from our galaxy are pulsars and magnetars. These rotate and produce beams of radiation similar to the light emitted by a lighthouse. So we think the newly discovered signal may have come from a magnetar or a powerful pulsar.”
Analyzing the eruption pattern of FRB 20191221A, researchers found striking similarities with emissions from pulsars and magnetospheres from our Milky Way. But they also encountered differences. The biggest difference is that FRB 20191221A appears a million times brighter. “From the characteristics of this new signal, we can conclude that there is a plasma cloud around the source that is very turbulent,” concludes Micheli.
The researchers hope to discover more periodic flashes from the same source, which can then be used as an astrophysical clock. For example, the frequency of explosions can be used to measure the expansion rate of the universe. But not only this. In fact, capturing more outbursts can also help us learn more about the still mystifying source and its character, as well as expand our understanding of neutron stars in general.
“This discovery raises the question of the reason for this strange signal. A signal we have not seen before,” says Micheli. “It also raises the question of how to 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. Astronomers will likely also find many similar periodic signals, which are likely to reveal many of the mysteries that exist.
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