Astronomers have detected a strange radio signal that periodically emits “like a heartbeat” and comes from the depths of space.
Scientists at the Massachusetts Institute of Technology (MIT) in the United States were surprised by the intensity of the radio bursts, as well as their regularity.
The signal is classified as fast radio (FRB), which are intense bursts of radio waves of unknown origin.
This one studied by scientists at MIT and other institutions is currently the longest-lasting FRB to date, with the clearest periodic pattern.
Called FRB 20191221A, the signal persists for much longer (in fact, about 1,000 times longer) than the typical FRB, and raises questions about what might be causing it.
FRBs usually last a few milliseconds at most, but FRB 20191221A lasts up to three seconds, with radio waves repeating every 0.2 seconds in what astronomers call a “clear periodic pattern.”
What could be causing it?
While the mysterious radio signals from space often provoke an enthusiastic conversation about the potential communication of the aliens, it is likely that the explanation comes from a rare type of star.
Astronomers suspect the signal could come from a type of neutron star, which is collapsed nuclei of extremely dense, rapidly rotating giant stars left over from supernovae.
Scientists, who publish their work in the journal Nature, say it could be caused by a radio pulsar or a magnetic star, both types of neutron stars.
“There aren’t many things in the universe that emit strictly periodic signals,” said Daniele Michilli of the Kavli Institute for Astrophysics and Space Research at MIT.
“The examples we know of in our own galaxy are radio pulsars and magnets, which rotate and produce a beacon-like beam emission. And we think this new signal could be a magnet or a pulsar with steroids.”
‘Boom, bum, bum’
The first FRB was discovered in 2007 and since then hundreds of similar flashes of radio waves have been detected throughout the universe.
The vast majority of FRBs discovered so far were unique, lasting a few milliseconds before disappearing.
FRB 20191221A was discovered in 2019, and Michilli immediately noticed the unusual data collected by the Canadian Hydrogen Intensity Mapping (CHIME) experiment.
“It was unusual. Not only was it very long, it lasted about three seconds, but there were periodic peaks that were remarkably accurate, emitting every fraction of a second – album, boom, boom – like a heartbeat. This is the first time the signal itself is periodic, ”he explained.
The team wants to detect more signals from the source, which they say could be used as an astrophysical clock.
They could study the frequency of eruptions and how they change as the source moves away from the Earth, to measure the speed at which the universe expands.
FRB 20191221A “a million times brighter”
Astronomers say similarities were found between FRB 20191221A radio bursts and those in our own galaxy.
However, the FRB 20191221A pulse appeared to be over a million times brighter than these other signals.
Michilli says that the light flashes can originate from a pulsar or magnet from a distant radio that is usually less bright as it rotates and, for some unknown reason, ejected a train of bright bursts, in a rare window. of three seconds that CHIME was fortunately positioned to capture.
“CHIME has now detected many FRBs with different properties,” Michilli said.
“We have seen some living inside very turbulent clouds, 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 plasma cloud that has of being extremely turbulent ”.
Michilli added that the detection raises more questions about what could trigger such an extreme signal that had never been seen before.
“Future telescopes promise to discover thousands of FRBs a month, and right now we can find many more of these periodic signals,” he said.