Read: A burst of light unlike any captured before But then astronomers found that some FRBs originated in larger, mellower galaxies too. So FRBs must come from these kinds of environments, they thought. When astronomers managed to trace an FRB to its home galaxy for the first time, they found a small, lively galaxy, where new stars blinked into existence more than 100 times faster than in our own Milky Way. But then astronomers found a repeater, a source of FRBs capable of erupting again and again, sometimes several times in less than a minute. The flashes were so intense, even after crossing unfathomable distances in space, that whatever had produced them seemed unlikely to survive the cataclysm. And then similar signals started showing up in observations at other telescopes.Īstronomers accepted that they had detected a real event, but they still thought FRBs were one-offs. The signal was thought to be a telescope artifact, a trick of light masquerading as a cosmic curiosity. The first FRB was discovered in 2007, buried deep in archival data of a telescope in Australia, while astronomers were looking for another astrophysical phenomenon. The discovery is an intriguing addition to a growing inventory of knowledge in a field whose earliest evidence was almost dismissed as a fluke. Read: What’s better than one mysterious cosmic signal? When Li and I spoke this week, she told me she’s still checking-and the rhythm is still there. Like so many people this year, Li has spent most of her days at home, rarely venturing beyond the walls of her small apartment in Bonn, Germany, but the Canadian observatory continues to scan the skies, catching the fleeting FRBs as little smudges of black against a plot of white noise. The paper on this discovery, published earlier this month, marked the end of formal observations in February. Astronomers traced the source to a spiral galaxy about 500 million light-years away, where it’s still going strong. The FRB, known by the bar-code-esque designation 180916.J0158+65, is the first to show this kind of regular cadence. (This is, perhaps, the purest definition of radio silence.) Li was monitoring FRBs, tracking their arrival times at a radio telescope in British Columbia, when she noticed that unusual pattern from one FRB source-four days on, 12 days off. In the past decade, astronomers managed to detect about 100 of them before they vanished. They show up without warning and flash for a few milliseconds, matching the radiance of entire galaxies.Īstronomers don’t know what makes them, only that they can travel for millions, even billions, of years from their sources before reaching us. She works on a Canadian-led project, CHIME, that studies astrophysical phenomena called “fast radio bursts.” These invisible flashes, known as FRBs for short, reach Earth from all directions in space. The pattern-the well-defined swings from frenzy to stillness and back again-persisted like clockwork for more than a year.ĭongzi Li, a doctoral student at the University of Toronto, started tracking these signals in 2019.
Then, another four days of haphazard pulses. For about four days, the radio waves would arrive at random.
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