Fast radio bursts are some of the most mysterious events known in astronomy, but they are slowly becoming better understood. Case in point: recent observations of a fast radio burst in the Milky Way reveals the powerhouse behind the blasts: a flaring magnetar.
FRBs could be cause by magnetic bursts of a neutron star. Credit: NASA’s Goddard Space Flight Center/S. Wiessinger
In 2007 astronomers first detected strange bursts of intense radio energy, known as (as you might have guessed) fast radio bursts, or FRBs for short. Subsequent observations – so far we’ve spotted only a couple dozen of them – revealed that these FRBs were 1) insanely powerful, and 2) coming from basically everywhere.
Indeed, the fact that they were coming from basically everywhere is the reason that astronomers figured that they were insanely powerful. In order to be detectable at extra-galactic distances, whatever is causing FRBs must be some of the most powerful explosions in the universe.
Additionally, to be that powerful in the radio end of the spectrum, there have to be magnetic fields involved. With strong enough magnetic fields, charged particles can wind themselves around in corkscrew paths, generating radio emissions.
It’s been suspected that magnetars – super-magnetized, rapidly-rotating neutron stars – may be the source of fast radio bursts, but all the known FRBs have been too far away to tell.
But recently, scientists caught a lucky break. Using the CHIME radio telescope, a group of astronomers were monitoring a magnetar in the Milky Way galaxy, a mere 30,000 light-years away. They were keeping a close eye on it because it was starting to flare up in X-ray emissions, and the astronomers were wondering if something else might be up.
They were right. Shortly after they began observations, the magnetar known only as SGR 1935+2154 began bursting in radio; a bona-fide fast radio burst, right there before our very telescopes.
Despite the new identification, scientists still aren’t exactly sure how a magnetar launches a fast radio burst. Hopefully we’ll get more lucky observations to tell us more.
CHIME/FRB Collaboration. “A bright millisecond-duration radio burst from a Galactic magnetar“. Nature 587, 54-58 (2020). DOI: 10.1038/s41586-020-2863-y