Gravitationally Lensed Supernova From 10 Billion Years Ago Could Crack Dark Energy Mystery

An international team of astronomers has discovered a unique supernova whose light has been traveling for more than 10 billion years — and whose gravitationally lensed images could provide a powerful new tool for measuring the universe's expansion rate and probing the nature of dark energy.

The object, designated SN 2025wny, is a superluminous supernova at a redshift of 2.01, making it one of the most distant stellar explosions ever observed in multiple gravitationally lensed images. A massive galaxy sitting between Earth and the supernova bends its light along several distinct paths, each of slightly different length, producing multiple images that arrive at different times. Because a supernova brightens and fades over weeks to months, each image effectively captures a different moment in the explosion's evolution — and the time delays between them are directly sensitive to the Hubble constant, the parameter that quantifies how fast the cosmos is expanding.

"No one has found a supernova like this before, and the nature of the system means it may be able to help solve some big problems in astrophysics such as the nature of the force that drives the expansion of the universe," said Dr. Daniel Perley, a reader in astrophysics at Liverpool John Moores University and a co-author on the study. Dark energy, the mysterious phenomenon thought to constitute roughly 68 percent of the universe's total energy content, is believed to be responsible for the accelerating expansion, yet its fundamental nature remains unknown.

The discovery carries special significance for the so-called Hubble Tension — a persistent disagreement between two leading methods of measuring the cosmic expansion rate. Observations of the cosmic microwave background, the afterglow of the Big Bang, yield one value for the Hubble constant, while measurements based on nearby galaxies and supernovae produce a notably different number. Precisely measured time delays from lensed supernovae like SN 2025wny could serve as an independent check, potentially indicating which result is correct. "Studies of lensed supernovae could indicate which of these two numbers we should really believe," Perley said.

The supernova was first detected by the Zwicky Transient Facility in California, but it was the Liverpool Telescope on La Palma that first resolved the multiple lensed images, confirming the gravitational lensing. Follow-up observations enlisted some of the world's most powerful facilities, including the Keck Telescopes in Hawaii, the Hubble Space Telescope, and the James Webb Space Telescope. PhD student Jacob Wise at LJMU's Astrophysics Research Institute was the first to recognize the lensed nature of the event, while collaborators at Stockholm University initially flagged the supernova candidate. The findings, published in The Astrophysical Journal Letters with 36 co-authors spanning institutions including Caltech and Stockholm University, mark the first confirmed discovery of a strongly gravitationally lensed superluminous supernova — opening a new observational window on the physics of cosmic expansion at an epoch when the universe was less than a quarter of its current age.