近日，意大利国立天体物理研究所的Sandro Mereghetti及其研究团队取得一项新进展。经过不懈努力，他们观测到附近星暴星系M82中的一颗巨大磁星耀斑。相关研究成果已于2024年4月24日在国际权威学术期刊《自然》上发表。

该研究团队报道了GRB 231115A的观测结果，其位置与星暴星系M82完全吻合。综合其光谱特性、爆发时长，以及在几小时内所观测到的X射线和光学对应物的极限情况，再加上缺乏引力波信号的证据，这次爆发无疑来自M82中一颗磁星的巨大耀斑。

据悉，磁星巨大耀斑是一种罕见的爆发事件，在不到1秒的时间里，年轻的中子星释放出高达10⁴⁷erg的伽马射线，磁场高达10^15-16G。大约50年来，在银河系和大麦哲伦星云的磁星上只观测到三次这样的耀斑。这个小样本可以通过星系外事件的发现而扩大，因为在不到一秒的时间里，巨大的耀斑的亮度就会达到10⁴⁶ergs^-1以上，这使得它们在几十兆秒差距的范围内都是可见的。然而，在这样的距离上，很难将它们与短伽马射线暴(GRB)区分开来。

附：英文原文

Title: A magnetar giant flare in the nearby starburst galaxy M82

Author: Mereghetti, Sandro, Rigoselli, Michela, Salvaterra, Ruben, Pacholski, Dominik Patryk, Rodi, James Craig, Gotz, Diego, Arrigoni, Edoardo, DAvanzo, Paolo, Adami, Christophe, Bazzano, Angela, Bozzo, Enrico, Brivio, Riccardo, Campana, Sergio, Cappellaro, Enrico, Chenevez, Jerome, De Luise, Fiore, Ducci, Lorenzo, Esposito, Paolo, Ferrigno, Carlo, Ferro, Matteo, Israel, Gian Luca, Le Floch, Emeric, Martin-Carrillo, Antonio, Onori, Francesca, Rea, Nanda, Reguitti, Andrea, Savchenko, Volodymyr, Souami, Damya, Tartaglia, Leonardo, Thuillot, William, Tiengo, Andrea, Tomasella, Lina, Topinka, Martin, Turpin, Damien, Ubertini, Pietro

Issue&Volume: 2024-04-24

Abstract: Magnetar giant flares are rare explosive events releasing up to 10⁴⁷erg in gamma rays in less than 1second from young neutron stars with magnetic fields up to 10^15-16G . Only three such flares have been seen from magnetars in our Galaxy and in the Large Magellanic Cloud in roughly 50years. This small sample can be enlarged by the discovery of extragalactic events, as for a fraction of a second giant flares reach luminosities above 10⁴⁶ergs^-1, which makes them visible up to a few tens of megaparsecs. However, at these distances they are difficult to distinguish from short gamma-ray bursts (GRBs); much more distant and energetic (10^50-53erg) events, originating in compact binary mergers. A few short GRBs have been proposed, with different amounts of confidence, as candidate giant magnetar flares in nearby galaxies. Here we report observations of GRB 231115A, positionally coincident with the starburst galaxy M82 . Its spectral properties, along with the length of the burst, the limits on its X-ray and optical counterparts obtained within a few hours, and the lack of a gravitational wave signal, unambiguously qualify this burst as a giant flare from a magnetar in M82.

DOI: 10.1038/s41586-024-07285-4

Source: https://www.nature.com/articles/s41586-024-07285-4