RADIO WAVES OF UNKNOWN ORIGIN HAVE SCIENTISTS PUZZLED

Fast radio bursts originating from outside the Milky Way were first detected almost 20 years ago. But what are they?

- DR KATIE MACK

You would think they would have been harder to miss: unimaginably powerful bursts of cosmic radiation, so bright they can blast our radio telescopes from billions of light-years away and occurring perhaps as often as a thousand times a day.

But fast radio bursts (FRBs) went undetected until 2007, and despite a decade and a half of investigation, remain one of the most enticing mysteries in astrophysics. Recent studies are providing new and promising hints about their origins, while at the same time illustrating why these cosmic firecrackers are so confounding in the first place.

When I first started hearing about FRBs in seminars, the big question wasn't so much: "What astrophysical source is causing this?", but rather: "Are we sure this isn't just a blip in the machine?" After all, whatever it was, it looked pretty suspicious.

An FRB is a burst of radio radiation that lasts around a millisecond and spreads out in frequency in a way that looks an awful lot like a blip from a pulsar (a rapidly spinning core of a collapsed massive star, known as a neutron star, that's left after a supernova explosion).