Astronomers spot potential first-ever 'superkilonova' in rare cosmic double explosion

Astronomers may have witnessed a rare cosmic event—what could be the first recorded 'superkilonova'. The discovery, published this month in The Astrophysical Journal Letters, involved two massive explosions in quick succession. Researchers described the findings as 'eye-opening' but stressed that further evidence is still needed to confirm the phenomenon.

The event, named AT2025ulz, began on 5 March 2025 when gravitational wave detectors LIGO and Virgo picked up unusual signals. These waves guided optical telescopes to a distant galaxy, UGC 9034, where a bright flash was spotted. Observatories including the Zwicky Transient Facility in California, the Vera C. Rubin Observatory in Chile, ESA's Gaia space telescope, and Pan-STARRS in Hawaii tracked the explosion's light curve, which peaked at a magnitude of around 18.5 in the r-band.

The data revealed something unexpected: first, a supernova erupted from a rapidly spinning star. Days later, a second explosion—a kilonova—followed, likely caused by the merger of two tiny neutron stars left behind. This sequence matches a long-standing theory about how such events could unfold, producing heavy elements like gold and uranium. Scientists believe the combined blasts scattered 'star stuff' across the galaxy, enriching space with elements essential for planets and life. The host galaxy's redshift of z=0.12 helped researchers model the merger using both gravitational waves and light, offering a rare multi-messenger view of the process.

The detection of AT2025ulz provides a possible first glimpse of a superkilonova, though confirmation will require more observations. If verified, the event would demonstrate how violent cosmic explosions forge and distribute elements across the universe. Researchers now aim to refine their models and search for similar occurrences in the future.