Astronomers have detected a radio signal from a far-off galaxy that flashes for up to three seconds on a regular basis.
Over a billion light-years distant, the signal is called FRB 20191221A and it’s classed as a “fast radio burst”—a radio pulse. Around 1,000 times longer than most FRBs, FRB 20191221A is now the longest-lasting and most regular radio signal known in the entire night sky.
Scientists think that the radio signal may be coming from a neutron star—what remains of the collapsed core of a giant star after it’s exploded as a supernova. Neutron stars spin rapidly.
Though the origin of FRBs are mysterious it’s hoped that each one’s frequency, and how they differ in distance from us, could tell scientists about the exact rate at which the universe is expanding. The first FRB was discovered in 2007.
FRB 20191221A was first detected on December 21, 2019. “It was unusual,” said Daniele Michilli, a postdoc in MIT’s Kavli Institute for Astrophysics and Space Research. “Not only was it very long, lasting about three seconds, but there were periodic peaks that were remarkably precise, emitting every fraction of a second — boom, boom, boom—like a heartbeat.”
So what could be the source of FRB 20191221A?
“There are not many things in the universe that emit strictly periodic signals,” said Michilli. “Examples that we know of in our own galaxy are radio pulsars and magnetars, which rotate and produce a beamed emission similar to a lighthouse. And we think this new signal could be a magnetar or pulsar on steroids.”
Types of neutron stars, a pulsar is a neutron stars that emits beams of radio waves and appears to pulse as the star rotates while a magnetar has extreme magnetic fields. The FRB 20191221A signal is a million times brighter than pulsars and magnetars in the Milky Way.
“From the properties of this new signal, we can say that around this source, there’s a cloud of plasma that must be extremely turbulent,” said Michilli. “Future telescopes promise to discover thousands of FRBs a month, and at that point we may find many more of these periodic signals.”
Wishing you clear skies and wide eyes.