FRBs typically last a few milliseconds, during which time they can outshine entire galaxies.
Since the first FRB was observed in 2007, astronomers have catalogued more than 100 FRBs from distant sources scattered across the universe, outside our own galaxy.
These detections were usually one-offs, flashing briefly before disappearing entirely.
Astronomers also observed a minority fast radio bursts multiple times from the same source, though with no discernible pattern.
But this latest FRB event, catalogued as FRB 180916.J0158+65, is the first to produce a periodic pattern of fast radio bursts.
The pattern begins with a noisy, four-day window, during which the source emits random bursts of radio waves, followed by a 12-day period of radio silence.
The astronomers observed that this 16-day pattern of fast radio bursts reoccurred consistently across more than 500 days of observations.
Kiyoshi Masui, assistant professor of physics in MIT’s Kavli Institute for Astrophysics and Space Research, said: “This FRB we’re reporting now is like clockwork.
The source is the most active FRB source CHIME has yet detected, and until recently it was the closest FRB source to Earth.
As the researchers plotted each of the 38 bursts over time, a pattern began to emerge: One or two bursts would occur over four days, followed by a 12-day period without any bursts, after which the pattern would repeat.
This 16-day cycle occurred again and again over the 500 days that they observed the source.
Professor Masui added: “These periodic bursts are something that we’ve never seen before, and it’s a new phenomenon in astrophysics.”
Explanations for this new extragalactic rhythm are wide-ranging.
One possibility is the periodic bursts may originate from a single compact object, such as a neutron star, that is both spinning and wobbling.
Assuming the radio waves emanate from a fixed location on the object, Earth would observe the radio waves as periodic bursts if the object is spinning along an axis and that axis is only pointed toward the direction of Earth every four out of 16 days.
Another possibility involves a binary system, such as a neutron star orbiting another neutron star or black hole.
If the first neutron star emits radio waves, and is on an eccentric orbit that briefly brings it close to the second object, the tides between the two objects could be strong enough to cause the first neutron star to deform and burst briefly before it swings away.
This pattern would repeat when the neutron star swings back along its orbit.