A group of astronomers from the Massachusetts Institute of Technology (MIT) and other research centers have detected a strange and persistent radio signal from a distant galaxy that seems to ‘beat’ with surprising regularity, as detailed in a study published on Wednesday (07.13.2022) by the journal Nature.
The signal was classified as a fast radio burst (FRB), a very intense emission of radio waves of unknown astrophysical origin that usually lasts a few milliseconds at most.
However, this new signal persists for up to three seconds, about 1,000 times longer than the FRB average. In this context, the team detected bursts of radio waves that repeated every 0.2 seconds in a clear periodic pattern, similar to the beating of a heart.
FRB 20191221A, as researchers have classified it, is currently the longest-lived FRB with the clearest periodic pattern ever discovered. The source of the signal is in a distant galaxy, several billion light-years from Earth.
Its origin remains a mystery, although astronomers suspect that the signal could come from a radio pulsar or a magnetar, both types of neutron stars, extremely dense and rapidly rotating collapsed cores of giant stars.
“There aren’t many things in the universe that emit strictly periodic signals. The examples we know of in our own galaxy are radio pulsars and magnetars, which rotate and produce lighthouse-like emission. And we think this new signal it could be a magnetar or a pulsar on steroids,” said one of the MIT authors Daniele Michilli.
On December 21, 2019, the Canadian Hydrogen Intensity Mapping Experiment (CHIME) radio telescope picked up a signal from a potential FRB, which immediately caught the attention of astronomers who were scanning the incoming data. .
“It was unusual. Not only was it very long, lasting about three seconds, but there were periodic spikes that were remarkably precise, emitting every fraction of a second – thump, thump, thump – like a heartbeat. It’s the first time that the signal itself is periodic,” recalled Michilli.
The main difference between the new signal and radio emissions from our own galactic pulsars and magnetars is that FRB 20191221A appears to be more than a million times brighter: “CHIME has now detected many FRBs with different properties. We have seen some that they live inside clouds that are very turbulent, while others appear to be in clean environments. From the properties of this new signal, we can say that around this source there is a cloud of plasma that must be extremely turbulent,” Michilli stressed.