They detect a mysterious radio burst in space that pulsates like a heartbeat


(CNN) — Astronomers have detected a mysterious radio burst in space with a distinctive pattern that resembles a heartbeat.

Astronomers estimate that the signal comes from a galaxy about a billion light-years away, but the exact location and cause of the explosion is unknown. A study detailing the findings was published Wednesday in the academic journal Nature.

Fast radio bursts, or FRBs, are intense bursts of radio waves lasting milliseconds and of unknown origin. The first FRB was discovered in 2007, and since then hundreds of these fast cosmic flashes have been detected from various distant points in the universe.

Many FRBs release super-bright radio waves that last only a few milliseconds at most before fading completely, and about 10% of them are known to repeat and follow patterns.
These types of 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 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 detected through CHIME on December 21, 2019 something that immediately caught their attention: a fast radio burst “peculiar in many ways,” according to Daniele Michilli, a postdoctoral researcher at the Kavli Institute for Astrophysics and Space Research at the Institute of Technology. from Massachusetts.

The signal, named FRB 20191221A, lasted up to three seconds, or about a thousand times longer than typical fast radio bursts.

Michilli was monitoring the data as it came in from CHIME when the outburst 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 precise, emitting every fraction of a second: thump, thump, thump, like a heartbeat. It is the first time that the signal itself is periodic.”

Although FRB 20191221A has not yet replicated, “the signal is made up of a train of consecutive spikes that we found separated by ~0.2 seconds,” he said in an email.

an unknown source

The research team doesn’t know the exact galaxy from which the outburst came, and even the distance estimate of a billion light-years is “highly uncertain,” Michilli said. While CHIME is great at looking for bursts of radio waves, it’s not as good at locating their points of origin.

However, CHIME is being enhanced through a project in which other telescopes, currently under construction, will observe together and be able to triangulate radio bursts to specific galaxies, he said. However, the signal contains clues as to where it came from and its possible cause.

“CHIME has now detected many FRBs with different properties,” said Michilli. “We have seen some that 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.”

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 strong magnetic fields, while radio pulsars release radio waves that appear to pulse as the neutron star spins. 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 think 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 their evolution could help astronomers better understand the rate of expansion of the universe.

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



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