An international research team has identified the likely power source behind a rare class of exceptionally luminous stellar explosions. By analyzing data from the Fermi Gamma-ray Space Telescope, scientists have confirmed that a specific, supercharged supernova, known as SN 2017egm, was likely fueled by the birth of a magnetar—a neutron star possessing an incredibly intense magnetic field.

Core-collapse supernovae occur when massive stars exhaust their fuel and implode, often leaving behind a dense neutron star or a black hole. While standard supernovae are well-documented, ‘superluminous’ events produce ten times the visible light of typical explosions. For nearly two decades, researchers have searched for definitive evidence of gamma-ray emissions from these events to understand the mechanism driving their extreme brightness. SN 2017egm, located 440 million light-years away in the galaxy NGC 3191, provided the first clear signal of such high-energy light.

The study suggests that the magnetar at the heart of the explosion acts as a central engine. As the magnetar spins hundreds of times per second, it generates a massive outflow of electrons and positrons, creating a ‘magnetar wind nebula.’ Within this environment, gamma rays are produced and subsequently reprocessed into lower-energy visible light, which accounts for the supernova’s extraordinary luminosity. This process allows the explosion to remain visible far longer and with greater intensity than standard stellar deaths.

While the magnetar model successfully explains the initial luminosity and gamma-ray timing of SN 2017egm, researchers noted that the later stages of the explosion’s fade-out may involve additional complex interactions. Future observations using next-generation ground-based facilities, combined with existing space-based observatories, are expected to provide further insights into these cosmic phenomena, offering a new window into the inner workings of the most powerful explosions in the universe.