Astronomers have detected mysterious, ultra-brief repeating energy bursts from deep space for only the second time in history, and some experts suggested they could be evidence of advanced alien life.
The origin of fast radio bursts (FRBs), millisecond-long pulses of radio waves, is unknown, but most scientists say they are generated by powerful astrophysical phenomena emanating from billions of light years outside our galaxy, the Milky Way – such as black holes or super-dense neutron stars merging together.
Some, however, including Prof Avi Loeb, from the Harvard-Smithsonian centre for astrophysics, have posited more outlandish theories, suggesting they could be evidence of incredibly advanced alien technology.
The new discovery, made by a Canadian-led team of astronomers searching for FRBs, was published in the journal Nature following a three-week period last summer during which the group detected 13 of the flashes using a new type of radio telescope, the Canadian Hydrogen Intensity Mapping Experiment (Chime), in British Columbia’s Okanagan Valley.
For only the second time ever, spanning more than 60 FRBs recorded to date, one of the FRBs was detected repeating.
The Arecibo radio telescope in Puerto Rico previously observed such repeating bursts in 2015, after FRBs were first detected by accident in 2007 when a burst was spotted in radio astronomy data that had been collected in 2001.
It is likely that many more FRBs with even lower frequencies often travel past our planet, and with technological advances we might be able to detect more of them.
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“Until now, there was only one known repeating FRB,” said a Chime astrophysicist, Dr Ingrid Stairs, from the University of British Columbia.
“Knowing that there is another suggests that there could be more out there. 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.”
The majority of the 13 FRBs showed signs of “scattering”, suggesting their sources could be powerful astrophysical objects in locations with special characteristics, the scientists said.
“That could mean in some sort of dense clump like a supernova remnant or near the central black hole in a galaxy,” said Dr Cherry Ng, a team member in the study from the University of Toronto. “But it has to be in some special place to give us all the scattering that we see.”
The new FRBs were recorded at unusually low radio frequencies. Most of those previously detected have had frequencies of around 1,400 megahertz (MHz), but the new ones fell within a range below 800 MHz. Seven of the new bursts registered at 400 MHz – the lowest frequency the Chime telescope can detect.
In 2017 Loeb and his Harvard colleague Manasvi Lingam proposed that FRBs could be leakage from planet-sized alien transmitters. Rather than being designed for communication, they would more likely be used to propel giant spaceships powered by light sails which bounce light, or in this case radio beams, off a huge reflective sheet to provide thrust, the scientists said.
“Fast radio bursts are exceedingly bright given their short duration and origin at great distances, and we haven’t identified a possible natural source with any confidence,” said Loeb in a statement after the publication of a previous paper in the Astrophysical Journal Letters. “An artificial origin is worth contemplating and checking.
“Science isn’t a matter of belief, it’s a matter of evidence. Deciding what’s likely ahead of time limits the possibilities. It’s worth putting ideas out there and letting the data be the judge.”
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