Fast Radio Bursts (FRBs) are millisecond flashes of radio waves of unknown physical origin. They originate far from the Milky Way, but their true cause remains a mystery. Only a few dozen FRBs have been detected so far and only one was observed repeating. Now a Canadian-led team is adding another 13 FRBs to the list, including another repeating one.
As reported in two papers published in Nature (here and here), the signals were detected by the brand-new radio telescope CHIME, the Canadian Hydrogen Intensity Mapping Experiment. Seven of the FRBs had incredibly low radio frequencies – the lowest frequencies in CHIME's range. This suggests that they might extend to even lower frequencies so some models will have to be reconsidered.
“Whatever the source of these radio waves is, it’s interesting to see how wide a range of frequencies it can produce," team member Arun Naidu, of McGill University, said in a statement. "There are some models where intrinsically the source can’t produce anything below a certain frequency.”
The repeating burst is called FRB 180814 and is thought to be half as close to us as the previous repeating one, FRB 121102. The latter is believed to originate from a dwarf galaxy 3 billion light-years away, possibly as a result of a neutron star moving through an extremely powerful magnetic field.
“Until now, there was only one known repeating FRB. Knowing that there is another suggests that there could be more out there," added CHIME team member Ingrid Stairs, an astrophysicist at the University of British Columbia. "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 team also observed a lot of scattering in the radio signals from the majority of the new FRBs, suggesting that the environments they originate from are leaving a distinct mark on them.
“That could mean in some sort of dense clump like a supernova remnant,” explained team member Cherry Ng, an astronomer at the University of Toronto. “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.”
The findings significantly expand what we know about FRBs. The mystery is yet to be unraveled, but we are getting much closer to finding out what processes power these incredible cosmic events.