Transcripts of 13792_Magnetar_Giant_Flare

[Music throughout] A high-energy outburst seen in April 2020 confirmed the surprising range of supermagnetized objects called magnetars. This blast of X-rays and gamma rays triggered instruments on several spacecraft. The eruption was over in the blink of an eye and originated from a galaxy about 11 million light-years away. Magnetars are part of the family of compact objects known as neutron stars, the crushed, leftover cores of exploded stars. What makes magnetars special are their incredibly strong magnetic fields — up to 1,000 times stronger than a typical neutron star’s. Sudden changes to this ultrastrong field are thought to drive brief, enormously powerful outbursts called giant flares. One giant flare in our own galaxy affected Earth’s upper atmosphere — from 28,000 light-years away. On April 15th, detectors on NASA’s Fermi, Swift, Mars Odyssey and Wind missions, as well as on the European Space Agency’s INTEGRAL satellite, picked up a rapid surge of X-rays and gamma rays. Using the arrival times of the signal at different spacecraft, astronomers pinned the burst to NGC 253, a bright, nearby galaxy. From start to finish, the event lasted 140 milliseconds — as fast as a finger snap. Astronomers see gamma-ray bursts, or GRBs, almost every day. We know that at least some of the shortest GRBs come from merging neutron stars more than 100 million light-years away. The April blast initially looked similar to these events. But a GRB located in our own galactic neighborhood should have appeared much brighter. As astronomers explored this new burst in detail, they found it looked less like a short GRB and more like a magnetar giant flare. Astronomers have recorded two such flares inside our own galaxy and a third in a satellite galaxy. All of these bursts displayed a spikey tail as they faded out. The spikes form as the flare's hot spot spins in and out of view, like a lighthouse beam. Current instruments can’t detect this feature in flares located at great distances, but other characteristics, such as their extremely fast rise in brightness, are unmatched by short GRBs. This fueled astronomers’ growing suspicions that short GRBs associated with galaxies in our neighborhood might really be magnetar giant flares. Now, the precise localization of the 2020 event to the disk of the Sculptor galaxy has unmasked them at last. Astronomers suspect that a few percent of observed short GRBs may in fact be giant flares — high-powered eruptions in our galactic back yard produced by the strongest magnets in the cosmos. NASA