Source of mysterious radio bursts found to be microwave ovens

Sydney Morning Herald : Fast radio bursts (FRBs) are millisecond-duration radio signals of extragalactic origin. Although some have been detected, many of them at the Parkes radio telescope in Australia, what causes them remains unknown. One possible source is a neutron star collapsing to a black hole. Since 2010, however, astronomers have been puzzled by the detection of similar radio bursts that were not coming from space but rather from Earth. Dubbed perytons, the brief events exhibit electromagnetic spectra similar to FRBs; in addition, both are emitted at 1.4 GHz, and both last about 250 milliseconds. Now Emily Petroff of Swinburne University of Technology in Australia and colleagues have solved the mystery: Perytons are emitted by microwave ovens being opened prematurely, before the timer pings. Although microwaves operate at a higher frequency of 2.3 –2.5 GHz, opening the door early causes the oven’s magnetrons to emit a radio burst at the lower, 1.4-GHz frequency before shutting down. Despite the mundane origin of perytons, the researchers say, FRBs remain “excellent candidates for genuine extragalactic transients.”