TORONTO: Scientists have detected the second repeating fast radio burst (FRB) ever recorded, a discovery that may help determine the origin of these mysterious signals which have been linked with advanced alien technology in the past.
Some scientists also believe that FRBs emanate from powerful astrophysical phenomena billions of light years away.
However, the source of these signals, originating from far outside our Milky Way galaxy, are not well understood.
In 2017, Harvard scientists have speculated that these FRBs might be leakage from planet-sized transmitters powering interstellar probes in distant galaxies.
They said that since a natural origin cannot be identified, an artificial or alien origin can be contemplated.
"Whatever the source of these radio waves is, it's interesting to see how wide a range of frequencies it can produce. There are some models where intrinsically the source can't produce anything below a certain frequency," said Arun Naidu of McGill University in Canada, who was part of the team that detected the signal.
The discovery of the extragalactic signal is among the first, eagerly awaited results from the Canadian Hydrogen Intensity Mapping Experiment (CHIME), a radio telescope inaugurated in 2017.
"Until now, there was only one known repeating FRB. Knowing that there is another suggests that there could be more out there," said Ingrid Stairs, a member of the CHIME team.
"And with more repeaters and more sources available for study, we may be able to understand these cosmic puzzles -- where they're from and what causes them," said Stairs, an astrophysicist at the University of British Columbia in Canada.
The repeating FRB was one of a total of 13 bursts detected over a period of just three weeks during the summer of 2018, while CHIME was in its pre-commissioning phase and running at only a fraction of its full capacity.
Additional bursts from the repeating FRB were detected in following weeks by the telescope, which is located in British Columbia's Okanagan Valley.
Of the more than 60 FRBs observed to date, repeating bursts from a single source had been found only once before -- a discovery made by the Arecibo radio telescope in Puerto Rico in 2015.
The majority of the 13 FRBs detected showed signs of "scattering," a phenomenon that reveals information about the environment surrounding a source of radio waves.
The amount of scattering observed by the CHIME team led them to conclude that the sources of FRBs are powerful astrophysical objects more likely to be in locations with special characteristics.
"That could mean in some sort of dense clump like a supernova remnant," said Cherry Ng, an astronomer at the University of Toronto in Canada.
"Or near the central black hole in a galaxy. But it has to be in some special place to give us all the scattering that we see," said Ng.
Ever since FRBs were first detected, scientists have been piecing together the signals' observed characteristics to come up with models that might explain the sources of the mysterious bursts and provide some idea of the environments in which they occur.
The detection by CHIME of FRBs at lower frequencies means some of these theories will need to be reconsidered.