Thirty thousand years ago, a dead star on the other side of the Milky Way emitted a powerful mix of radio and X-ray energy. On April 28, 2020, that bell hovered over Earth, causing alarms at observers around the world.
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The impression of artist of a magnetar launching a burst of X-rays and radio waves across the galaxy
The signal was there and went away in half a second, but that’s all scientists needed to confirm that they had discovered something remarkable: the first ‘fast radio burst’ (FRB) to emerge from a known star within the Milky Way, according to a study published July 27 in The Astrophysical Journal Letters.
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Since their discovery in 2007, FRBs have surprised scientists. The bursts of powerful radio waves last only a few milliseconds, but generate more energy during that time than the Earth’s sun does in a century. Scientists have yet to determine what caused these explosions, but they have suggested everything from collisions of black holes to the pulse of early constellations as possible explanations. To date, every known FRB has originated from another galaxy, hundreds of millions of light-years away.
Related: 11 fascinating facts about our Milky Way galaxy
This FRB is different. Telescopic observations suggest that the burst came from a known neutron star – the fast-spinning, compact core of a dead star, which wraps a sun of valuable mass in a ball in the city – about 30,000 light-years from Earth in the constellation Vulpecula. The stellar remnant fits into an even earlier class of star called a magnetar, named for its incredibly powerful magnetic field, which is capable of emitting intense amounts of energy long after the star itself has died. It now appears that magnetars are almost likely the source of at least some of the universe’s many mysterious FRBs, the study’s authors wrote.
“We have never seen a burst of radio waves, resembling a rapid radio burst, of a magnetar before,” lead author Sandro Mereghetti, of the National Institute of Astrophysics in Milan, Italy, said in a statement. “This is the first observational connection between magnets and fast radio bursts.”
The magnetar, named SGR 1935 + 2154, was discovered in 2014 when scientists saw it emit powerful bursts of gamma and X-rays at random intervals. After a moment of silence, the dead star was awakened with a powerful X-ray in late April. Sandro and his colleagues discovered this burst with the European Space Agency’s (ESA) integral satellite, designed to capture the most energetic phenomena in the universe. At the same time, a radio telescope in the mountains of British Columbia, Canada, discovered an explosion of radio waves coming from the same source. Radio telescopes in California and Utah confirmed the FRB the next day.
A simultaneous explosion of radio waves and X-rays has never before been detected by a magnetar, the researchers wrote, pointing strongly to these stellar remains as plausible sources of FRBs.
Of crucial importance, added ESA scientist Erik Kuulkers, this finding was only possible because multiple telescopes on Earth and in orbit were able to capture the burst simultaneously, and at many wavelengths across the electromagnetic spectrum. Further collaboration between institutions is needed to “bring into focus the origins of these mysterious phenomena,” Kuulkers said.
Originally published on Live Science.
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