Canadian radio telescope takes the search for puzzling fast radio bursts into a new era

Alan Boyle
One of the radio antennas of the Canadian Hydrogen Intensity Mapping Experiment, or CHIME, spreads out beneath the night sky near Penticton, B.C. (CHIME Photo)

A new radio telescope in British Columbia’s Okanagan Valley has detected 13 new sources of mysterious extragalactic phenomena known as fast radio bursts, including the second known source of repeated bursts.

And the experiment is just barely getting started.

The Canadian Hydrogen Intensity Mapping Experiment, or CHIME, picked up the radio signatures of the bursts over the course of three weeks in July and August, while the telescope was in its pre-commissioning phase and running at only a fraction of its design capacity.

Fast radio bursts, also known as FRBs, are powerful spikes of radio emissions that emanate from galaxies beyond our own Milky Way and last for mere milliseconds. Only 60 FRB sources have been detected, including the 13 announced today.

“Their origin is still unknown,” said the University of British Columbia astronomer Deborah Good, one of the co-authors of two papers about the detections published today by the journal Nature.

Good and McGill University astrophysicist Victoria Kaspi discussed the CHIME/FRB Collaboration’s findings during a briefing at the American Astronomical Society’s winter meeting in Seattle.

CHIME is a fixed radio telescope that covers more area than a football field and passively scans the skies 24/7 as Earth rotates. It was originally designed to delve into the mystery surrounding dark matter by mapping the distribution of interstellar hydrogen, but it also turns out to be well-suited to take on the mystery surrounding fast radio bursts.

Some scientists have speculated that the sources of FRBs might be rotating neutron stars with extremely strong magnetic fields, or even super-advanced radio beacons operated by extraterrestrial civilizations. Whatever they are, CHIME’s initial detections suggest that the $13 million radio telescope will be a powerful tool for tracking down more of the bursts.

Kaspi said CHIME quickly detected a source that sent out a series of six fast radio bursts. “The fact that one out of the 13 initial CHIME FRBs is a repeater suggests that these repeaters are not as rare as we thought previously,” she said.

The only other known FRB repeater was discovered in 2012 using the Arecibo radio telescope in Puerto Rico. The second repeater is much closer than the first one, but the pattern of emissions appears to be similar — “which is interesting,” Kaspi said.

Another interesting twist has to do with the radio frequencies of the newly detected bursts. Before CHIME, astronomers noted that most of the previously detected bursts had frequencies around 1,400 MHz, and some wondered whether CHIME would detect any bursts at all in its range of 400 to 800 MHz. But Kaspi said the FRB signals were strong all the way down to the lowest frequency CHIME could detect.

“This is good news for radio telescopes that are sensitive at lower radio frequencies,” she said. “They have yet to see FRBs, but there’s a good chance that they will get to see them.”

Some of the signal-scattering patterns suggest that the sources of the bursts have to be in special types of locations — for example, in supernova remnants, star-forming regions or around black holes. The frequency patterns also share some characteristics with magnetars, those rotating neutron stars that have long been suspected to be FRB sources.

Kaspi cautioned against reading too much into the magnetar connection. “The luminosity difference is many, many orders of magnitude,” she said. Nevertheless, the similarities were intriguing enough to catch the attention of Caltech astronomer Aaron Pearlman, whose research focuses on magnetars. Pearlman shared the stage with the CHIME researchers at today’s AAS news conference.

“As soon as the press conference is over, I’m reading the paper,” he told journalists.

The CHIME/FRB Collaboration includes scientists from UBC and McGill as well as the University of Toronto, the Perimeter Institute for Theoretical Physics and the National Research Council of Canada. The telescope is located at the Dominion Radio Astrophysical Observatory near Penticton, B.C. It was built with principal funding from the Canadian Foundation for Innovation with partnership from the Provinces of British Columbia, Ontario and Quebec. The CHIME project also receives funding from NSERC and CIFAR.

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