| Nov 04, 2020 |
Source of mysterious radio waves from space pinpointed
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(Nanowerk News) The identification of the source of a fast radio burst within the Milky Way is reported in three papers published in Nature this week. Observations of the bright pulses of radiowaves, made from multiple satellite- and ground-based telescopes, suggest that they originate from a magnetar in our Galaxy. The implications of these findings and the current understanding of fast radio bursts are discussed in an accompanying Review.
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Fast radio bursts were first discovered in 2007. Although astronomers have rapidly added new observations and probed many theories to explain these events, it has been difficult to fully understand the underlying physics. Determining the source of the bursts is also challenging, as they last only a few milliseconds and therefore are hard to localize.
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Most theories propose that the source could be neutron stars, dense remnants of giant stars following a supernova explosion.
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Three independent studies suggest that a magnetar (a neutron star with an extremely powerful magnetic field) is the source of a fast radio burst named FRB 200428. On 28 April 2020, the Canadian Hydrogen Intensity Mapping Experiment (CHIME) and The Survey for Transient Astronomical Radio Emission 2 (STARE2) in the USA both detected a fast radio burst from the same region of the sky.
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Paul Scholz and the CHIME Collaboration report that FRB 200428 originates in a known Galactic magnetar called SGR 1935+2154. Christopher Bochenek and the STARE2 team concur, reporting observations of the fast radio burst that coincided with an outburst of X-rays from SGR 1935+2154.
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The same region of the sky was monitored by the Five-hundred meter Aperture Spherical Telescope (FAST) in China, report Bing Zhang and colleagues. Although the Chinese telescope did not observe FRB 200428, it did record extremely energetic explosions called short ?-ray bursts, offering insights into the events that underlie fast radio bursts. Zhang and colleagues conclude that fast radio bursts associated with short γ-ray bursts are rare.
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The collective discoveries highlight the importance of international scientific cooperation as well as sky coverage from multiple locations, write Amanda Weltman and Anthony Walters in an accompanying News & Views article. The latest findings suggest that magnetars can produce at least some, and maybe all, fast radio bursts, concludes Bing Zhang in a Review. However, he does not completely rule out other sources.
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References
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Nature, "A bright millisecond-duration radio burst from a Galactic magnetar"
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Nature, "A fast radio burst associated with a Galactic magnetar"
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Nature, "No pulsed radio emission during a bursting phase of a Galactic magnetar"
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