Astronomers just quintupled the number of known repeating fast radio bursts

The new haul could help reveal what causes these cryptic flashes of radio waves from deep space

CONSTANT VIGILANCE A Canadian telescope called CHIME scans the sky each night for brief, bright bursts of radio waves from deep space. Now CHIME has spotted eight new bursts that flash repeatedly.

Andre Renard/Dunlap Institute/University of Toronto/CHIME

By Lisa Grossman

August 14, 2019 at 3:10 am

Astronomers have found eight new fast radio bursts that flash on and off.

That new haul brings the total of known repeating fast radio bursts, or FRBs, to 10, compared with the 60 or so nonrepeating FRBs that have been spotted, researchers report August 9 at arXiv.org. Studying the cryptic bursts could reveal what phenomena cause these brief, brilliant flares of radio waves from deep space.

The first nonrepeating burst was discovered only in 2007, so “FRBs are still quite new,” says astrophysicist Cherry Ng of the University of Toronto. But “the repeater population is larger than we might think. They’re not that unique,” she says.

Ng and colleagues spotted the newly discovered repeating FRBs using the Canadian Hydrogen Intensity Mapping Experiment, or CHIME, in British Columbia. The telescope also found the second known repeating FRB in August 2018 (SN: 2/2/19, p. 12).

The new batch of repeat bursts could help astronomers start to figure out the sources of these flashes of radio energy, as well as how they might be different from their nonrepeating kin.

For instance, radio waves from the first known repeat FRB, reported in 2016, were scrambled and tossed around by electrons on the way to Earth. That suggests the repeating FRB’s source is in a dense, turbulent environment, such as a supernova remnant or a neutron star orbiting a black hole (SN: 2/3/18, p. 6). But the energy from some of the new bursts seems to have had a less tumultuous journey, suggesting that these repeating FRBs hail from a calmer environment.

Each burst from a repeat FRB also seems to last longer than an individual FRB, about 10 milliseconds per repeat burst versus one millisecond for a nonrepeater. That finding could support the idea that the two types of radio blasts have entirely different sources, although Ng thinks it’s too soon to be sure (SN: 8/3/19, p. 10). “Maybe don’t bet too much money on it,” she says.

CHIME also has found many more nonrepeating FRBs in the last year, Ng says. That research is yet to be published, but “it will be a game changer,” she says.