Discovery Published in Nature: Magnetar Explosion in Galaxy M82
Wed, 01/05/2024

During a sky observation, the European Space Agency's INTEGRAL satellite suddenly detected a burst of gamma rays emanating from the nearby galaxy M82, located 12 million light-years away. Just a few hours later, the ESA's XMM-Newton space telescope searched for any traces of the explosion but found none. Astronomers realized that the intense signal had been generated by a brilliant extragalactic explosion from a magnetar, a young neutron star with an exceptionally strong magnetic field.

The research team, led by the National Institute of Astrophysics (INAF–IASF) in Milan, published the results of this discovery in the prestigious journal Nature. The research involved the Universities of Milano-Bicocca, Milano, Insubria, and the IUSS School for Advanced Studies in Pavia.

In November 2023, INTEGRAL detected a sudden burst from a rare object. For just a tenth of a second, a brief burst of energetic gamma rays appeared from the direction of the bright galaxy M82. INTEGRAL satellite data were received at the INTEGRAL Scientific Data Center in Geneva, from where a gamma-ray burst alert was sent to astronomers worldwide, only 13 seconds after its detection. The Integral Burst Alert System (IBAS) provided an automatic localization coinciding with the nearby galaxy M82.

Confirmation of the extragalactic explosion was obtained through observations with XMM-Newton, which showed only hot gas and stars in the galaxy, with no signs of a luminous X-ray and visible light explosion. This excluded the possibility that the event was a common gamma-ray burst caused by the collision of two neutron stars, confirming instead that it was an explosion from a magnetar.

This is the first documented case of a magnetar explosion so distant from our galaxy. The importance of these discoveries lies in the opportunity to better study magnetars outside the Milky Way and understand their energetic processes. Research continues, with the hope of detecting other magnetars in nearby galaxies and thus expanding our knowledge of these enigmatic celestial objects.

The full publication entitled "A magnetar giant flare in the nearby starburst galaxy M82" is available today in the prestigious scientific journal Nature.

The international study, led by the National Institute of Astrophysics and published in the journal Nature, also involved the Universities of Milano-Bicocca, Milano, Insubria, and the IUSS School for Advanced Studies in Pavia.

Two of our astrophysicists, Prof. Paolo Esposito and Prof. Andrea Tiengo, participated in the study, primarily contributing to the analysis and interpretation of data collected by the XMM-Newton satellite.