Astronomers are using the sophisticated IceCube observatory at the South Pole to work out if mysterious fast radio bursts (FRBs) emit high-energy neutrinos. The connection between the phenomena might clarify the many unknowns researchers are struggling with in both fields.
FRBs are incredibly brief and powerful emissions of radio waves. Lasting just a few milliseconds, they release an incredible amount of energy but their cause is unknown. Just two dozen of these signals have been detected and only one, FRB 121102, has been seen to repeat itself.
This ephemeral quality makes finding their source more difficult. They are too quick to be followed by telescopes, so a team of researchers from the University of Wisconsin decided to look at the data from the IceCube observatory and see if the events emitted neutrinos. This would help shed a light on their nature.
"Astrophysical neutrinos and fast radio bursts are two of the most exciting mysteries in physics today," team member Justin Vandenbroucke said in a statement. "There may be a link between them."
As reported in the Astrophysical Journal, the team couldn’t link a single neutrino detection to the FRB observations. This might seem demoralizing but not finding things still tell us a lot about potential sources. The researchers were able to estimate the upper limit of neutrinos that any of these events might produce.
"We can say that the amount of energy emitted by each burst as neutrinos is less than a certain amount, which can then be compared to predictions from individual theories," Vandenbroucke explained. The repeating FRB is believed to be produced by a neutron star with an astonishing magnetic field but it’s not clear if the other detections come from similar objects. There might be two or more phenomena causing the FRBs.
Estimates suggest that at least 10,000 FRBs are produced in the visible universe every day and a recent estimate says that there could be one every second assuming that they all are like FRB 121102. New telescopes like the Square Kilometer Array might be able to see up to one FRB per minute.
"As the number of bursts is expected to grow dramatically in the next couple years, these constraints will become even stronger – or we will make a detection," Vandenbroucke added. "We've ruled out gamma-ray bursts and we've strongly constrained the possibility of black holes. There could be even more exotic physics going on."
The puzzle of FRBs has gained a few more pieces but the picture is far from complete.
