Universe Radio on Repeat

Looking at the universe in radio waves is a fascinating sight.  For one, the radio sky is very weak; If you placed your cellphone on the Moon facing back at Earth, it would be brighter than all other radio sources in the entire sky by a factor of a million.  But as with every other part of the electromagnetic spectrum, it has scientific value in studying the sky.  Over the past decade, astronomers have been identifying several Fast Radio Bursts (FRB), short bursts of radio waves from different places in the universe that last for a few short seconds.  These are generally isolated events that are disjointed, but for the first time astronomers are seeing an FRB that is repeating itself, from a source far beyond the edge of the Milky Way.

Discovered by the Arecibo Radio Telescope, the repeating FRB is puzzling astronomers. Credit: Danielle Futselaar

When you look around the sky and see an FRB, it makes sense to assume that it is the result of a cataclysmic event, such as a supernova, or a neutron star collapsing into a black hole.  But with the discovery of a repeating source, it means that some FRB’s are being produced by something else, maybe even a stable repeating event.  It would have to be something powerful though, as FRBs are highly energetic and last for only a few thousandths of a second.

By measuring an effect called the plasma dispersion, astronomers have concluded that FRBs likely originate beyond our own galaxy.  The newly discovered repeating bursts have three times the dispersion measure than what would be expected for a source from within the Milky Way.

It’s a scientific shakeup to have this discovery announced this week, especially because of a paper released in the journal nature last week that suggests FRBs originate from high energy sources such as gammy-ray bursts.  Gamma-ray bursts would cause FRBs that intrinsically occur only once, not allowing for a repeating bursts.  And so the universe provides us with another strange result just in time.

To follow up observations of the distant source, astronomers will need a new generation of astronomical interferometers. Radio telescopes will need a much higher resolution to see the source of something so distant and short lived.  But the real power of a repeating FRB is that it may continue to repeat for years, giving astronomers a continuous source of data to help characterize this and other radio bursts.

Just another step in listening to the radio stations of the universe.



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