Ever since their discovery more than a decade ago, enigmatic flashes of radio waves have puzzled astronomers. These “fast radio bursts” (FRBs) pop up with startling frequency and intensity all across the sky, each emerging from unknown faraway extragalactic sources and packing the power output of up to hundreds of millions of suns into just a few fleeting milliseconds.
Now researchers are closing in on their origins.
A team studying one particular FRB some three billion light-years from Earth—known as FRB 121102, the only ever seen to repeat—has found it is engulfed by an extremely strong magnetic field. Such extreme magnetic fields have only previously been seen near neutron stars around the supermassive black hole at the center of our galaxy. The team suggests this FRB’s mysterious source is a very young and fast-spinning, highly magnetized neutron star—a magnetar—that may be orbiting a massive black hole. The findings are published in the January 11 Nature.
“For the first time, we’re getting some sense of the environment around the burst’s source—remote sensing from three billion light-years away!” says study co-author Shami Chatterjee, an astronomer at Cornell University. “We recognize this is piling one exotic thing atop another: We want an energetic magnetar without precedent, and we also want to put it next to a massive black hole. But we do have a similar example in our own galaxy. ”The magnetars near the Milky Way’s center, however, have yet to be seen emitting FRBs, which tend to come from much, much further away.
A curious property of FRBs confirms their vast distance from us—their radio waves have been “dispersed” by their passage through clouds of electrons that fill the space between stars and galaxies, smeared out in proportion to how far they have journeyed to reach Earth. That means FRBs could become best-in-class probes of cosmic structure, allowing researchers to determine not only the distance to any given FRB but also how much intervening material lies in interstellar and intergalactic space along its path. But to fully realize that revolutionary potential, astronomers must better understand what gives rise to FRBs in the first place, and whether the lone known repeating burster, FRB 121102, is a typical example or a fluke.
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