Fast radio bursts (FRB) are what astronomers call the mysterious and currently unexplained flashes of radio signals that originate from very distant sources. While they are incredibly brief, lasting at most a few milliseconds, these bursts are powerful enough to be detected across the universe.
One source known as FRB 121102, located in a dwarf galaxy 3 billion light years from Earth, is particularly intriguing as it is the only FRB known that repeats. So far scientists have detected more than 200 high-energy pulses coming from it, but have been unable to explain what exactly is going on.
Various explanations have been put forward, including the (remote) possibility that the signals originate from an advanced alien civilisation.
Now, new data has shed light on FRB 121102. However, the mystery of its origins are still uncertain.
An international collaboration of scientists using the Green Bank Telescope in West Virginia and the William E. Gordon Telescope in Puerto Rico have confirmed that,the source of the bursts is embedded in an “extreme environment”, which is among the most highly magnetised regions of space ever observed.
These types of magnetic fields are usually only seen around black holes and the centres of galaxies, but the FRB could plausibly be explained by a combination of other extreme astrophysical circumstances.
“I had to read my email a few times to really digest it. I kept thinking, ‘No way, that can’t be right,'” said Victoria Kaspi, from the Canadian Institute for Advanced Research. “We found something that is clearly in an extreme place and the extreme location may create a phenomenon that is one of the biggest astrophysical mysteries of recent times.”
Based on their puzzling data, the scientists suggest the fast radio bursts may be coming from a highly magnetised neutron star – known as a magnetar – which is in the vicinity of a massive black hole 10 to 100 million times the size of the Sun and produces an extreme magnetic field or spewing out hot gases.
Their findings are published in the journal Nature.
According to the scientists, the length of the radio pulses – which range between 30 microseconds to 9 milliseconds in duration – indicate that the source could be as small as 10km across, which is roughly the size of a typical neutron star.
Neutron stars are the collapsed cores of larger stars that once measured between 10 and 29 solar masses. They are the smallest and densest stars known to exist.
However, many factors are still unexplained by this theory.
“At this point, we don’t really know the mechanism,” said Vishal Gaijar from the University of California, Berkeley’s SETI Research Center and Breakthrough Listen – both organizations which are setup to search for signs of intelligent extra-terrestrial communications.
“There are many questions, such as, how can a rotating neutron star produce the high amount of energy typical of an FRB?”
Among other explanations for the source, is the possibility that a magnetar could be interacting with a huge cloud of material originating from the death of the original star.
But could the radio emissions be coming from an advanced alien civilisation?
“We can not rule out completely the ET hypothesis for the FRBs in general,” Gajjar said.
But even if FRB 121102 is not alien in origin, as is likely, it is still an extremely impressive phenomenon. In a single millisecond-long-flash of radio emissions, the source radiates enough energy to equal our Sun’s entire output for a day.
“This is exotic. If we had one of these on the other side of our own galaxy – the Milky Way – it would disrupt radio here on Earth, and we’d notice, as it would saturate the signal levels on our smartphones,” said Shami Chatterjee from Cornell University. “Whatever is happening there is scary. We would not want to be there.”