Radio signal frequency captured in space looks like heartbeat, study says

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

Astronomers estimate the signal came from a galaxy about a billion light-years away, but the exact location and cause of the explosion are unknown.

A study detailing the findings published this Wednesday (13) in the journal Nature.

Fast radio bursts, or FRBs, are intense millisecond bursts of radio waves 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 in the universe.

Many FRBs release super-bright radio waves that only last a few milliseconds at most before disappearing completely, and about 10% of them 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 identify them is a radio telescope called the Canadian Hydrogen Intensity Mapping Experiment (Chime) at the Radio Dominion Astrophysical Observatory in British Columbia, Canada.

This 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, detected something on December 21, 2019, that immediately caught their attention: a rapid burst of radio that was “quirky in many ways,” according to Daniele Michilli, a postdoctoral researcher at the Kavli Institute of Astrophysics and Space at the Massachusetts Institute of Technology.

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

Michilli was monitoring the data coming from the Chime when the explosion occurred. The signal is the longest lasting fast radio burst 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 — thump, thump, thump — like a heartbeat. This is the first time that the signal itself is periodic.”

While the FRB 20191221A burst has yet to repeat itself, “the signal is formed by a line of consecutive spikes that we find separated every 0.2 seconds,” he said in an email.

an unknown source

The research team does not know the exact galaxy from which the explosion originated and even the estimated distance of a billion light-years is “highly uncertain,” Michilli said.

While Chime is well equipped to look for bursts of radio waves, it is not so good at locating their points of origin.

However, the device is being upgraded through a project where additional telescopes, currently under construction, will observe together and be able to triangulate radio bursts to specific galaxies, he said.

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

“Chime has now detected many FRBs with different properties,” said Michilli. “We’ve 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 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 remnants after the death of a giant star, 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 rapid radio burst appears to be more than a million times brighter than these emissions. “We think this new signal could be a magnetar or pulsar on steroids,” Michilli said.

The research team will continue to use Chime to monitor the skies for more signs of this radio burst, as well as others with a similar periodic signal. The frequency of radio waves and how they change can be used to help astronomers learn more about the expansion rate of the universe.

“This detection raises the question of what could cause this extreme signal that we’ve never seen before, and how we can use this signal to study the universe,” said Michilli.

“Future telescopes promise to discover thousands of FRBs per month, and at that point, we may find many more of these periodic signals.”