Astronomers have discovered a mysterious radio signal pulsing rhythmically “like a heartbeat” in space.
The signal, named FRB 20191221A, is a fast radio burst (FRB) – an extremely powerful burst of radio waves – coming from an unknown origin.
Most FRBs last a few milliseconds at most, but the new signal is much longer — around 3 seconds — making it the longest FRB ever detected. In addition, it generates bursts of radio waves that repeat every 200 milliseconds in a heartbeat-like rhythm, making it the FRB with the clearest periodic pattern ever discovered. The researchers published their findings on July 13 in the diary of nature (opens in new tab).
Related: Strange type of fast radio burst spotted 3 billion light-years away
Fast radio bursts discharge more energy than that in a few milliseconds Sun does in a year. Astronomers have long puzzled over the source of these sudden, bright flashes. But that’s where FRBs break out efficiently galaxies Millions — or even billions — of light-years away, and flare up quickly and often only once, scientists have struggled to identify the sources of these explosions.
In 2020, the very first discovery of an FRB in our own Milky Way galaxy allowed scientists to trace the origins of the FRB to a magnetar, a highly magnetized, rapidly rotating shell of a dead star. Magnetars and their less magnetized cousins Pulsars are special types of neutron stars, which are ultradense stellar bodies left behind by the explosive death of stars. Pulsars and magnetars have unusually strong magnetic fields, often millions or trillions of times stronger than Earth‘s, and as they spin rapidly in space they emit a beam of intense electromagnetic radiation from their poles, like giant lighthouses. However, scientists are not sure if all FRBs are from magnetars.
While most FRBs are one-off events, some are recurring—sometimes in a single brief burst and sometimes over multiple periods.
“There aren’t many things in the universe that emit strictly periodic signals,” says study co-author Daniele Michilli, an astrophysicist at the Massachusetts Institute of Technology. said in a statement. “Examples we know of in our own galaxy are radio pulsars and magnetars that spin and produce a beam emission similar to a lighthouse. And we think this new signal could be a magnetar or a pulsar on steroids.”
Astronomers first spotted the new signal using the Canadian Hydrogen Intensity Mapping Experiment (CHIME), a radio telescope designed to detect radio waves emitted by hydrogen in one of the universe’s earliest stages — if mysteriously, it was hypothetical dark energy first caused the universe to begin expanding at an accelerating rate. On December 21, 2019, while scanning the sky for distant hydrogen radio emissions, CHIME picked up the strange signal.
“It was unusual,” Michilli recalled. “Not only was it very long, lasting about 3 seconds, but there were periodic spikes that were remarkably precise, sending out every split second – boom, boom, boom – like a heartbeat. This is the first time that the signal itself is periodic.”
After analyzing the pattern created by the signal’s radio bursts, the researchers found that its emissions were very similar to those of radio pulsars and magnetars discovered in our own galaxy. But there was one key difference: FRB 20191221A appears to be a million times brighter, according to the scientists.
They’re not sure what might be behind this intense luminosity, but they suggested it might be caused by a source that isn’t normally that bright but for some unknown reason fired off a series of brilliant flashes that CHIME happened to catch .
“CHIME has now discovered many FRBs with different properties,” Michilli said. “We’ve seen some living in very turbulent clouds, while others appear to be in a clean environment. Based on the properties of this new signal, we can say that around this source there must be a plasma cloud that is extremely turbulent.”
To learn more about the bursts and their mysterious source, researchers are now preparing to hopefully capture more pulses from FRB 20191221A. This would help the team investigate what might be causing the pulses and learn more about the unexpected behavior of neutron stars.
“This discovery raises the question of what could be causing this extreme signal that we have never seen before and how we can use this signal to study the Universe,” Michilli said. “Future telescopes promise to discover thousands of FRBs every month, and at this point we could find many more of these periodic signals.”
Originally published on Live Science.
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