Gravitationally Lensed Superluminous Supernova Discovered
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An international team of astronomers led by Oskar Klein Center (OKC) researcher joel Johansson has discovered SN 2025wny, the first spatially resolved, gravitationally lensed superluminous supernova ever observed. The finding provides a striking confirmation of Einstein’s theory of General Relativity and a rare window into a powerful stellar explosion from the early Universe.
A cosmic magnifying glass reveals a record-distant explosion
The supernova SN 2025wny lies at an extraordinary distance – its light has travelled around 10 billion years to reach us. At the time the light was emitted, the Universe was only about 4 billion years old.
A supernova this distant would normally be far to faint to discover from earth. Though, thanks to two foreground galaxies, acting as a gravitational lens, the supernova appears about 50 times brighter, making it visible to ground-based telescopes.
“This is nature’s own telescope,” says Joel Johansson, lead author and researcher at the Oskar Klein Centre, Stockholm University. “The magnification lets us study a supernova at a distance where detailed observations would otherwise be unachievable.”
A new method to probe the expansion of the Universe
The gravitational lensing effect does more than magnifying the supernova – it produces several distinct, spatially separated images of the same explosion.Each lensed image of the supernova takes a slightly different path around the deflecting galaxies, reaching Earth at different times. These time differences offer an self-reliant, highly promising method to measure the Hubble constant, which describes how fast the Universe is expanding.
A current hot topic in modern cosmology is the so called “Hubble tension”, which refers to the growing discrepancy between two precise and independent measurements of how fast the Universe is expanding; one based on observations of the early cosmos and the other on nearby objects. This may suggest that our current cosmological model is incomplete, or that one of the methods currently used is flawed.
Ariel Goobar, group leader at the OKC and part of joel Johansson’s research team considers this new approach to be a technical breakthrough: “A lensed supernova with multiple, well-resolved images, provides one of the cleanest ways to measure the expansion rate of the Universe. SN 2025wny is an crucial step toward resolving one of cosmology’s most meaningful challenges,” Ariel Goobar says.
A surprising and exceptionally hot explosion
Superluminous supernovae are a relatively newly discovered class of cosmic explosions,which are extremely energetic and rare in nature. Because the Universe is expanding, ultraviolet light emitted by SN 2025wny is “redshifted” to optical wavelengths, and can be detected with telescopes on the ground. The team’s observations show that SN 2025wny is unusually hot and