Astronomers have identified a bright supernova from over 10 billion years ago, its light gravitationally lensed into multiple images by a foreground galaxy. This unique observation allows simultaneous views of different stages of the explosion. The time delays between images could reveal details about the universe's expansion rate and dark energy.
Researchers announced the discovery of SN 2025wny, a strongly gravitationally lensed superluminous supernova at redshift z = 2.01. The explosion's light, traveling for more than 10 billion years, was bent by a galaxy between it and Earth, creating multiple images. Each image arrived at different times due to varying path lengths, enabling astronomers to observe the supernova at slightly different evolutionary stages simultaneously. Dark energy, thought to make up about 68% of the universe and drive its accelerating expansion, remains poorly understood, and this event offers a potential clue. The time differences between images depend on the universe's expansion rate, according to measurements planned by the team from Liverpool John Moores University, Caltech, Stockholm University, and others. > '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. > 'We are seeing the light from this distant supernova split into multiple images, what we call 'gravitationally lensed',' explained Jacob Wise, a PhD student at the Astrophysics Research Institute. The supernova was first detected by the Zwicky Transient Facility in California. The Liverpool Telescope in La Palma was the first to observe the multiple images, confirming the lensing. Further observations used the Keck Telescopes in Hawaii, Hubble Space Telescope, and James Webb Space Telescope. This could address the Hubble Tension, where cosmic microwave background studies and nearby galaxy measurements yield conflicting Hubble constant values. > 'Studies of afterglow of the Big Bang give one number for the so-called Hubble constant... while studies of nearby galaxies give a different number,' Perley noted. The findings appear in 'Discovery of SN 2025wny: A Strongly Gravitationally Lensed Superluminous Supernova at z = 2.01' in The Astrophysical Journal Letters.