Astronomers have just identified a peculiar repeating pattern of fast radio bursts (FRBs) emanating from an unknown source outside our galaxy. The discovery has been described as ‘a new phenomenon in astrophysics,’ and has stunned space experts.
FRBs are usually short, intense bursts of radio waves believed to be the result of a small, distant, extremely dense cosmic bodies. They normally last for a few milliseconds, during which time they are able to outshine entire galaxies. Still, what exactly those objects might be is still an enigma in astrophysics.
A ‘New Type of Phenomenon’
After the first FRB was discovered in 2007, experts have found more than 100 FRBs coming from distant places scattered across the Universe, outside the Milky Way. These identifications were usually one-offs, exploding for a short time before disappearing completely.
Astronomers have also spotted a minority of fast radio bursts a few times from the same source, but there was no clear pattern to it. However, this latest FRBs event, named FRB 180916.J0158+65, is the first to generate a periodic pattern of FRBs.
The standard begins with a loud, four-day period, during which the source produces random bursts of radio waves, followed by a 12-day period of silence. The experts have observed that this 16-day pattern of FRBs took place in a consistent manner across over 500 days of observations.
Kiyoshi Masui, assistant professor of physics at MIT’s Kavli Institute for Astrophysics and Space Research, said: “This FRB we’re reporting now is like clockwork. It’s the most definitive pattern we’ve seen from one of these sources. And it’s a big clue that we can use to start hunting down the physics of what’s causing these bright flashes, which nobody really understands.”
Professor Masui is a member of the CHIME/FRB collaboration operating and examining data collected by the Canadian Hydrogen Intensity Mapping Experiment (CHIME). From September 2018 to February 2020, CHIME identified 38 FRBs from a single source, cataloged as FRB 180916.J0158+65.
Is There an Explanation for the Pattern?
This event was traced to a star-churning area on the margins of a gigantic spiral galaxy, 500 million light-years from Earth. The source is the most active FRB source CHIME has yet spotted, and until not long ago, it was the closest FRB source to Earth.
As the scientists individually charted the 38 bursts over time, a pattern began to show up: one or two explosions would take place over four days, followed by a 12-day period with no bursts, after which the pattern would repeat. This 16-day standard repeatedly happened over the 500 days they examined 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 pattern are different. One probability is the periodic flashes may come from a single compact cosmic body, such as a neutron star that is both rotating and wobbling. With the presumption that radio waves are emanating from a stationary area on the object, astronomers from Earth would be able to only observe the waves as periodic flashes if the cosmic body is also rotating around an axis and that axis is pointing toward the direction of our planet every four out of 16 days.
Another probability is a binary system, such as a neutron star spinning around another neutron star or black hole. However, as of now, there is no clear explanation for this new type of pattern astronomers have discovered.