Mysterious repeating energy bursts have been detected for only the second time.
Fast
radio bursts, or FRBs, are radio emissions that appear temporarily and
randomly, making them not only hard to find, but also hard to study.
The latest signals to be detected reached Earth from a galaxy 1.5 billion light years away.
The most likely explanation is that they were created by powerful objects in space.
Experts
have debated whether black holes or super-dense neutron stars are
responsible, but others have suggested more outlandish theories.
Among
them is Professor Avid Loeb, from the Harvard-Smithsonian Centre for
Astrophysics in the US, who believes that they could be evidence of
incredibly advanced alien technology.
Over a period of three weeks last summer the team detected 13 of the
flashes using a new type of radio telescope, the Canadian Hydrogen
Intensity Mapping Experiment
FRB's were first detected accidentally in 2007, when a burst signal was spotted in radio astronomy data collected in 2001.
The new discovery, reported in the journal Nature, was made by a Canadian-led team of astronomers on the hunt for FRBs.
Over
a period of three weeks last summer the team detected 13 of the flashes
using a new type of radio telescope, the Canadian Hydrogen Intensity
Mapping Experiment (Chime).
They found that one of the FRBs was repeating.
Of
more than 60 FRBs detected to date, such repeating bursts have only
been picked up once before, by the Arecibo radio telescope in Puerto
Rico in 2015.
Where the FRBs come from is not known -
although they are thought to emanate from sources billions of light
years away outside our galaxy, the Milky Way.
Chime
astrophysicist Dr Ingrid Stairs, from the University of British
Columbia, Canada, 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.'
Most of the 13 FRBs showed signs of
'scattering' that suggest their sources could be powerful astrophysical
objects in locations with special characteristics, the scientists said.
Team
member Dr Cherry Ng, from the University of Toronto, Canada, said:
'That could mean in some sort of dense clump like a supernova (exploding
star) 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.'