A Mysterious Rhythm Is Coming From Another Galaxy


Astronomers have been tracking fast radio bursts for years, but they’ve never caught one like this before.

For about four days, the radio waves would arrive at random. Then, for the next 12, nothing.

Then, another four days of haphazard pulses. Followed by another 12 days of silence.

The pattern—the well-defined swings from frenzy to stillness and back again—persisted like clockwork for more than a year.

Dongzi Li, a doctoral student at the University of Toronto, started tracking these signals in 2019. 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. They show up without warning and flash for a few milliseconds, matching the radiance of entire galaxies.

FRBs are beacons of a kind, and astronomers have detected more than is widely known. In January, members of CHIME wrote in a paper posted on the preprint repository arXiv.org that they have detected 700 FRBs in less than a year. The catalog, when it is formally published, will increase the number of known signals sevenfold. As these radio waves propagate through space, they pass through all kinds of matter, from the most luminous galaxies to nearly invisible wisps of cosmic dust, slowing down here and there. These encounters are encoded in the radio waves, and scientists can pick them out when the signals reach us. Astronomers are particularly interested in studying the wispy material that lies between galaxies, because “we have no information other than what FRBs are beginning to give us,” says Shami Chatterjee, an astrophysicist at Cornell University who studies FRBs and was not involved in the new research. To see inside this expanse, astronomers need the help of these strange signals that they still barely understand.

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