Fast Radio Bursts (FRBs) are rare intense emissions of radio waves that last only a fraction of a second and have traveled to us through intergalactic distances. Only a few dozens of these events have been observed, spotted serendipitously, and only two were known to repeat. Now astronomers from the CHIME/FRB collaboration have spotted an incredible eight more repeating ones.
Given the scarcity of detections, astronomers are still wrapping their heads about what can possibly be causing them. The one-off FRBs are a flash in the cosmic pan and so far only a few have been caught in the act, giving astronomers time to follow up observations with other telescopes.
The repeating ones, on the other hand, have given researchers more to work with. FRB 121102, which has been seen repeating many times, has been pinpointed to a distant dwarf galaxy 3 billion light-years away. It is potentially generated by a neutron star moving in an intense magnetic field. The second one, FRB 180814, is estimated to be half as far. It was also identified using the Canadian Hydrogen Intensity Mapping Experiment, or CHIME.
The new events continue to show something that the CHIME/FRB collaboration had spotted when they first detected FRB 180814. The repeating FRBs have wider signals compared to the 12 non-repeating events, they announced last January. This suggests that while the effect appears similar, there are multiple sources in space that can release such incredible, and incredibly brief, emissions. Many, but not all of the repeaters, show a lot more substructures in their emissions, again suggesting a complexity not seen in the non-repeating ones.
There is also significant variation in duration and number of repetitions. As detailed in the pre-print paper, which has been accepted for The Astrophysical Journal Letters, six of them were caught repeating just once. One, FRB 181119, was observed repeating three times.
"There is definitely a difference between the sources, with some being more prolific than others," physicist Ziggy Pleunis of McGill University told Science Alert. "We already knew from FRB 121102 that the bursts can be very clustered: sometimes the source doesn't burst for hours and hours and then suddenly you get multiple bursts in a short amount of time. We have observed the same thing for FRB 180916.J0158+65, for which we report 10 bursts in this paper."
There is still so much that we don’t know about these events but these new observations will provide new insights in the phenomena. Latest estimates suggest there could be around 100 FRBs per day in the sky, so we just need to keep looking to find more.