Mysterious radio signals have reached Earth – from a galaxy 1.5 billion light years away.
The strange beams are known as fast radio bursts (FRBs) – and last only a millisecond.
It has been suggested they could be messages from alien civilisations with technology far advanced to our own.
But the Canadian team believe they are more likely to be caused by the left overs of an exploding star – or supernova.
They could also be coming from a supermassive black hole – now thought to be the central power stations of galaxies.
One of the blasts repeats six times – and seems to originate from the same location.
Intriguingly, it is the second time this phenomenon has been recorded.
When they burped into space the first complex cells were only beginning to appear on Earth. It has taken them that long to arrive.
The flashes described in two papers in Nature are among 13 new FRBs detected over a period of only three weeks last summer.
Scientists have long been searching for the source as they arrive with great force – but last only a tiny amount of time.
It’s been suggested they are emerging from some kind of “extreme” environment – but nobody has definitively shown where they are being sent from.
That has led to speculation they could be coming from a huge undiscovered star, jets emerging from a black hole – or even an artificial source such as alien life.
They are so bright they produce as much energy in the blink of an eye as the Sun pumps out in 12 months – enough to run humanity for ten trillion years.
Professor Ingrid Stairs, an astrophysicist at British Columbia University in Canada, said: “The bursts are estimated to originate from a distance of around 1.5 billion light years – approximately half the distance of the other repeating burst, FRB 121102.”
Similarities indicate the possibility of the same emission mechanisms or propagation effects, they said.
They were picked up by researchers using the CHIME (Canadian Hydrogen Intensity Mapping Experiment) telescope in British Columbia.
At least seven were recorded at 400 megahertz (Mhz) – the lowest frequency to date.
This suggests the bursts could be observed at even lower frequencies than the revolutionary instrument is capable of recognising.
CHIME team member Prof Stairs said: “Until now, there was only one known repeating FRB.
“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.”
More than 60 have been discovered since they were first identified just over a decade ago.
But only FRB 121102 that was picked up by the Arecibo radio telescope in Puerto Rico in 2015 has repeated – until now.
They came from about three billion light years away. What’s more the lowest radio frequency recorded previously was 700 Mhz.
Given the telescope – mounted in British Columbia’s Okanagan Valley – has already detected a second repeating FRB the researchers believe many more will follow.
Before CHIME began to gather data in 2017 some scientists wondered if the range of frequencies it had been designed for would be too low to pick up FRBs.
Most had been found near 1400 MHz – well above the telescope’s 400 to 800 capability.
The majority of the 13 new FRBs showed signs of “scattering” – revealing information about the environment surrounding the source. This led the team to conclude they come from powerful astrophysical objects more likely to be in places with special characteristics.
Team member Dr Cherry Ng, an astronomer at Toronto University, said: “That could mean in some sort of dense clump like a supernova remnant.
“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.”
Ever since FRBs were first detected, scientists have been piecing together the signals’ observed characteristics to come up with models that might explain where they originate.
Their detection at lower frequencies means some of these theories will need to be reconsidered.
Team member Dr Arun Naidu, a space physicist at McGill University in Montreal, said: “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
“We now know the sources can produce low-frequency radio waves and those low-frequency waves can escape their environment, and are not too scattered to be detected by the time they reach the Earth.
Team member Prof Tom Landecker, an astrophysicist at the National Research Council of Canada, added: “That tells us something about the environments and the sources.
“We haven’t solved the problem – but it’s several more pieces in the puzzle.”
by Mark Waghorn