On 15 November 2023, Integral detected a burst of gamma-rays for only a tenth of a second. The detection was sent to the Integral science data centre in Geneva, where software determined it came from the nearby galaxy M82. The small square on Integral’s map shows the location of the burst. The blue circle on the two cut-out images shows the corresponding location.
To learn more about the explosion, scientists swiftly directed XMM-Newton to observe in X-rays, and used ground-based optical telescopes, including the Italian Telescopio Nazionale Galileo (TNG) to follow-up in visible light.
XMM-Newton’s observations only show hot gas and the stars in the galaxy. There is no fading source of X-rays coming from the burst itself. The visible image by TNG only shows light from M82, with again no additional afterglow from the explosion.
With no corresponding detection in X-rays and visible light, the burst was identified as a giant flare from a magnetar in the M82 galaxy. Magnetars are extremely magnetic neutron stars and rotate quickly. Their giant flares are exceptionally rare with only three measured from magnetars in our galaxy before this one.
Read more about this discovery
[Image description: Part of the sky measured by the gamma-ray detector on ESA’s Integral satellite. Vague blue blobs dot a dark-blue map of the sky. One blob is much brighter than the others and two images show a cut-out zoom-in on this blob. One of the cut-outs shows X-rays from the galaxy and the other shows an observation in visible light. On both these two cut-out images only the galaxy M82 is seen, and no additional signals from the bright spot.]