Fast radio bursts are coming from a dwarf galaxy three billion light years away CREDIT: ESO
Cosmic radio waves which have puzzled astronomers for more than a decade, and even led to speculation that they were made by aliens, are probably produced by a huge neutron star, scientists have said.
Telescopes first picked up Fast Radio Bursts in 2001 and they have been recorded hitting Earth in a regular pattern ever since.
They last just a few milliseconds but seem to carry as much energy as the Sun releases in a month, suggesting they must come from a huge source of power.
Although pulsars are known to emit bursts of radio waves, they do not do so regularly or with anything like the power of FRBs. The mystery signals led to speculation that they could be the first hint of an advanced alien civilisation.
Now scientists have traced the origin of the waves to a dwarf galaxy more than three billion light years from Earth, where a powerful neutron star called a magnetar could have formed.
They found the signal's home by focussing on one recurring burst which had been detected at the Arecibo Observatory in Puerto Rico and managed to pick up the mystery bust nine more times over a six month period in 2016.
By tracing the orientation of the bursts their origin was narrowed down to a region about 100 light years in diameter.
Deep imaging of that region by the Gemini North Telescope in Hawaii turned up an faint dwarf galaxy which was discovered to also emit low-level radio waves.
Such galaxies are thought to hold massive, highly magnetic and rapidly rotating neutron stars called magnetars, which could hold enough energy to emit huge solar flares.
It means that the bursts picked up by telescopes erupted from the star before the first complex lifeforms appeared, and have been travelling ever since.
"We are the first to show that this is a cosmological phenomenon. It's not something in our backyard. And we are the first to see where this thing is happening, in this little galaxy, which I think is a surprise," Dr Casey Law said.
"Now our objective is to figure out why that happens."
Dr Law, team leader Dr Shami Chatterjee of Cornell University and other astronomers on the team will present their findings today at the American Astronomical Society meeting in Grapevine, Texas. The work is also published in the scientific journal Nature and Astrophysical Journal Letters.
Other theories suggest the signals are coming from material which is being jettisoned from the region surrounding a supermassive black hole.
"Finding the host galaxy of this FRB, and its distance, is a big step forward, but we still have much more to do before we fully understand what these things are," Dr Chatterjee said.