In 2007, astronomers digging through archival data from six years prior, found a very strong, very brief burst of radio emission coming from an unidentified source in space. The detection, sometimes called the Lorimer burst after the lead astronomer on the project, was the first discovery of its kind. It introduced us to a new class of objects dubbed fast radio bursts or FRBs for short. “Fast” because these blips are very short—less than 5 milliseconds in duration. So chop one second into a thousand parts and you’re looking at less than five of your pieces.
The “radio” portion of the moniker is due to the fact that the emission is detected by radio telescopes surveying the sky at radio wavelengths. They are called “bursts” because the signals disappear as quickly as they appeared, without warning and, so far, without explanation.
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Since 2007, astronomers have added 17 more bursts to the list of known FRBs. However, their origins are still a bit of a mystery because their defining characteristics, the very reasons they are so interesting, also make them challenging to study.
Radio telescopes also usually have to make a choice: spatial resolution or field of view. In other words, single dish radio telescopes like Parkes and Arecibo can survey the sky more efficiently than arrays of dishes like the Very Large Array near Socorro, New Mexico. However, that large field of view comes with a price: the typical resolution of the Very Large Array is 150 times better than Arecibo and more than 600 times that of Parkes.
Thus, telescopes like the Very Large Array typically cannot survey the sky fast enough to reliably detect such a short event—you’d have to get really lucky in a right place, right time sort of way—but the blurred vision of the single dish telescopes that do detect the bursts aren’t able to pinpoint where exactly they come from. Locating the source of an FRB is especially challenging because they don’t repeat themselves making followup observations useless.
Assuming that you can convince yourself that your one-time, nonrepeating, extremely short signal is a real one—if that sounds difficult, it should!—then whatever explanation you have for its origin must explain why it doesn’t, in fact, repeat. Thus several astronomers have hypothesized that FRB phenomena arise from cataclysmic events like the violent death of a star or the merger of two black holes.
