A team of scientists have discovered exciting extragalactic signals: the second-ever recorded fast radio burst (FRB) that repeats.
The signal was picked up by the Canadian Hydrogen Intensity Mapping Experiment (CHIME) telescope, which was introduced in 2017 from a team of scientists hailing from the University of Toronto (U of T), McGill University, Perimeter Institute for Theoretical Physics, National Research Council of Canada, and the University of British Columbia (UBC), among others.
FRBs are short radio wave bursts originating from far beyond our own galaxy, “but who’s exact nature is unknown,” according to Caltech.
The first FRB was discovered in 2007, and several have been found since then, roughly 60 bursts observed from five telescopes, reports MIT. However, only two have ever been found to be repeating—FRB 121102 discovered in 2015 by the Arecibo radio telescope, and CHIME’S latest discovery called FRB 180814.J0422+73.
“Until now, there was only one known repeating FRB,” says Ingrid Stairs, CHIME team member and an astrophysicist at UBC. “Knowing that there is another suggests that there could be more out there. 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.”
According to CNN, the new repeating FRB “was recorded six times coming from the same location, 1.5 billion light-years away.” The repeating burst was recorded along with 12 singular radio bursts during the summer of 2018 “when CHIME was in its pre-commissioning phase and running at only a fraction of its full capacity,” according to U of T.
A phenomenon known as scattering was present in most of the 13 FRBs, which can give a few hints toward the bursts’ origin. Judging from the amount of scattering, scientists believe “powerful astrophysical objects” were the source, according to U of T, located in regions “with special characteristics.”
“That could mean in some sort of dense clump like a supernova remnant or near the central black hole in a galaxy,” says Cherry Ng, astronomer at U of T’s Dunlap Institute for Astronomy & Astrophysics, and CHIME team member. “But, it has to be in some special place to give us all the scattering that we see.”
CHIME detects from 400 MHz to 800 MHz, and scientists were previously concerned that its frequency range was too low to even detect FRBs. Their fears have thus been calmed, and now some believe FRBs can be detected at even lower frequencies, since some near CHIME’s minimum were quite bright in nature, according to U of T.
“[We now know] the sources can produce low-frequency radio waves and those low-frequency waves can escape their environment, and are not too scattered to be detected by the time they reach the earth. That tells us something about the environments and the sources. We haven’t solved the problem, but it’s several more pieces in the puzzle,” says Tom Landecker, CHIME team member from the National Research Council of Canada.
CHIME also has what some call a revolutionary design.
“The telescope has no moving parts. Instead it uses digital signal processing to ‘point’ the telescope and reconstruct where the radio waves are coming from,” says Kiyoshi Masui, MIT assistant professor of physics. “This is done using clever algorithms and a couple of giant computer clusters that sit beside the telescope and crunch away at the data in real time.”
The CHIME results were published January 9 in two papers, “A second source of repeating fast radio bursts,” and “Observations of fast radio bursts at frequencies down to 400 megahertz,” in the journal Nature. The research team also presented their findings the same day at Seattle’s American Astronomical Society meeting.