Mysterious radio signal in space has the pattern of a heartbeat

A mysterious radio burst with a pattern similar to a heartbeat has been detected in space.

Astronomers estimate that the signal came from a galaxy about a billion light-years away, but the exact location and cause of the burst remain unknown. A study detailing the results was published Wednesday in Nature magazine.

Fast radio bursts, or FRBs (Fast Radio Bursts), are intense bursts of radio waves only milliseconds in duration, with unknown origins. The first FRB was discovered in 2007, and since then, hundreds of these fast, cosmic flashes have been detected coming from many distant points across the universe.

Many FRBs give off very bright radio waves that only last a few milliseconds at most before disappearing completely, and about 10% of these are known to repeat and have patterns.

Fast radio bursts are so fast and unexpected that they are difficult to observe.

One resource used to detect them is a radio telescope called the Canadian Hydrogen Intensity Mapping Experiment (CHIME) at the Dominion Radio Astrophysical Observatory in British Columbia, Canada.

This radio telescope, in operation since 2018, constantly observes the sky and, in addition to fast radio bursts, is sensitive to radio waves emitted by distant hydrogen in the universe.

Astronomers using CHIME spotted something on December 21, 2019, that immediately caught their attention: a fast burst of radio that was “peculiar in many ways,” according to Daniele Michilli, a postdoctoral researcher at the Kavli Institute of Institute for Astrophysics and Space Research at the Massachusetts Institute of Technology.

The signal, named FRB 20191221A, lasted up to three seconds – which is about 1,000 times longer than typical fast radio bursts.

Michilli was monitoring the data as it arrived from CHIME when the burst occurred. It was the longest-lasting FRB detected to date.

“It was unusual,” Michilli said. “Not only was it very long, lasting about three seconds, but there were periodic spikes that were remarkably accurate, emitting every fraction of a second – boom, boom, boom – like a heartbeat. This was the first time the signal itself was periodic.”

Although FRB 20191221A has yet to repeat itself, “the signal is formed by a string of consecutive peaks that we found to be separated by ~0.2 seconds,” Michilli said in an email.

an unknown origin

The research team does not know the exact galaxy from which the burst originated, and even the estimated distance of 1 billion light-years is “very uncertain”, Michilli said. While CHIME is prepared to look for bursts of radio waves, it is not so good at locating their points of origin.

However, CHIME is being improved through a project where additional telescopes, currently under construction, will observe together and be able to triangulate radio bursts to specific galaxies, Michilli said.

But the signal contains clues about where it came from and what may have caused it.

“CHIME has already detected many FRBs with different properties,” added Michilli. “We have observed some living within very turbulent clouds, while others appear to be in clean environments. From the properties of this new signal, we can say that around this origin, there is a plasma cloud that must be extremely turbulent.”

When the researchers analyzed FRB 20191221A, the signal was similar to emissions released by two different types of neutron stars, or the dense aftermath of a giant star’s death, called radio pulsars and magnetars.

Magnetars are neutron stars with incredibly powerful magnetic fields, while radio pulsars release radio waves that appear to pulsate as the neutron star rotates. Both stellar objects create a signal similar to the flashing beam of a lighthouse.

The fast radio burst appears to be more than a million times brighter than these emissions. “We believe that this new signal could be a magnetar or a pulsar on steroids,” Michilli said.

The research team will continue to use CHIME to monitor the skies for more signals from this radio burst, as well as others with a similar, periodic signal. The frequency of radio waves and the way they change could be used to help astronomers learn more about the rate at which the universe is expanding.

“This discovery raises the question of what could cause this extreme signal that we’ve never observed before, and how we can use this signal to study the universe,” said Michilli. “Future telescopes promise to discover thousands of FRBs a month, and by then we may find many more of these periodic signals.”

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