Astronomers at the Massachusetts Institute of Technology (MIT) and other universities in the U.S. and Canada have found a strange, persistent radio signal coming from a faraway galaxy. The signal appears to flash with unusual regularity.
“There are not many things in the universe that emit strictly periodic signals. Examples that we know of in our own galaxy are radio pulsars and magnetars, which rotate and produce a beamed emission like a lighthouse. And we think this new signal could be a magnetar or pulsar on steroids,” says Daniele Michilli, a postdoc at MIT’s Kavli Institute for Astrophysics and Space Research.
Tag as a fast radio burst or FRB, the signal is a short, very strong burst of radio waves with an unknown source in space that usually lasts no more than a few milliseconds. But this new signal can last up to three seconds, which is about 1,000 times longer than a typical FRB.
Within this window, the team found bursts of radio waves that repeat every 0.2 seconds in a clear periodic pattern, like a heart beating. This is the FRB with the clearest periodic pattern that has been found to date, and it is also the one that has been found to last the longest.
The signal’s origin is in a distant galaxy billions of light-years away from Earth. The source of the signal is unknown, but astronomers believe it could be a radio pulsar or a magnetar, both of which are types of neutron stars that are extremely dense and quickly spinning disintegrated cores of giant stars.
On the other hand, the Canadian Hydrogen Intensity Mapping Experiment, or CHIME, an interferometric radio telescope made up of four large parabolic reflectors at the Dominion Radio Astrophysical Observatory in British Columbia, Canada, recently made the most recent detection of a radio flash since the discovery of the first FRB in 2007. CHIME is a radio telescope that uses interferometry to detect radio flashes.
CHIME continuously monitors the sky as the Earth rotates, looking for radio waves emitted by hydrogen in the very early stages of the universe. It is also sensitive to fast radio bursts, and since it began observing the sky in 2018, it has detected hundreds of FRBs.
CHIME is made up of four massive cylindrical radio antennas that are roughly the size and shape of snowboarding half-pipes and are located at the Dominion Radio Astrophysical Observatory, which is run by the National Research Council of Canada in British Columbia, Canada. CHIME is a stationary array that contains no moving parts.
As the Earth spins, the telescope collects radio signals from the part of the sky each day. While most radio astronomy is done by swivelling a large dish to focus light from various parts of the sky, CHIME stares at the sky motionless and focuses incoming signals using a correlator — a powerful digital signal processor capable of processing massive amounts of data at a rate of approximately 7 terabits per second, equivalent to a small percentage of global internet traffic.
CHIME’s ability to reconstruct and ‘look’ in thousands of directions simultaneously, allowing researchers to detect FRBs thousands of times more frequently than a traditional telescope, is due to digital signal processing.
The study, which was partially funded by the Canada Foundation for Innovation, stated that the discovery raises the question of what could have caused this extreme signal that has never been seen before, as well as how the researchers can use this signal to study the universe. Future telescopes are expected to find thousands of FRBs per month, and astronomers may find many more of these periodic signals at that point.