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A mysterious radio burst with a heartbeat-like pattern 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 explosion are unknown. A study detailing the findings was published in the journal Wednesday Nature.
Fast radio bursts, or FRBs, are intense, millisecond bursts of radio waves of unknown origin. The first FRB was discovered in 2007, and since then hundreds of fast, cosmic flashes have been detected from various, distant points in the universe.
Many FRBs emit super-bright radio waves that last at most a few milliseconds before disappearing completely, and about 10% of them are known to repeat and have patterns.
Fast radio bursts are so fast and unpredictable that they are difficult to observe.
One source used to detect them is a radio telescope called the Canadian Hydrogen Intensity Mapping Experiment, or CHIME, at the Dominion Radio Astrophysical Observatory in British Columbia. Canada.
Operating since 2018, this telescope constantly monitors the sky and is sensitive to radio waves emitted by distant hydrogen in the universe in addition to fast radio bursts.
Astronomers using CHIME saw something on December 21, 2019 that immediately caught their attention: a fast radio burst that was “unique in many ways,” according to postdoctoral researcher Daniele Michilli. At the Massachusetts Institute of Technology’s Kavli Institute for Astrophysics and Space Research.
The signal, called FRB 20191221A, lasted up to three seconds—about 1,000 times longer than typical fast radio bursts.
Michilli was monitoring incoming data from CHIME when the explosion occurred. The signal is the longest-lasting fast radio burst to date.
“It was extraordinary,” Michilli said. “Not only was it very long, about three seconds, but there were periodic spikes that were pretty precise, emitting every fraction of a second like a heartbeat — boom, boom, boom. The signal itself is periodic for the first time. ”
Although FRB 20191221A has yet to repeat itself, “the signal is formed by a train of successive peaks that we found to be separated by ~0.2 seconds,” he said.
The research team doesn’t know exactly which galaxy the burst came from, and even the estimated distance of a billion light-years is “very uncertain,” Michilli said. While CHIME is good at looking for bursts of radio waves, it’s not very good at finding their points of origin.
However, CHIME is being improved through a project currently under construction in which additional telescopes will observe together and triangulate radio bursts to specific galaxies, he said.
But the signal contains clues about where it came from and what might be causing it.
“CHIME has now detected many FRBs with different properties,” Michilli said. “We saw some living in very turbulent clouds, and others in a clear environment. From the characteristics of this new signal, we can say that there is a plasma cloud around this source, which must be extremely turbulent.”
When the researchers analyzed FRB 20191221A, the signal resembled emissions from two different types of neutron stars, or dense remnants of the death of a giant star called a radio pulsar and a magnetar.
Magnetars are neutron stars with incredibly strong magnetic fields, while radio pulsars emit radio waves that appear as pulses as the neutron star spins. Both stellar objects produce a signal similar to the flashing beam from a lighthouse.
The fast radio burst appears to be over a million times brighter than these emissions. “We think this new signal could be a magnet or a pulsar on steroids,” Michilli said.
The research team will continue to use CHIME to monitor the sky for more signals from 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 rate at which the universe is expanding.
“This detection raises the question of what could cause this extreme signal, which 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 per month, and we may find even more of these periodic signals.”
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