A rare gravitationally lensed supernova could help astronomers determine how fast the universe is expanding and shed light on dark energy.
Astronomers may be closer to understanding one of the greatest mysteries in cosmology: dark energy, the unknown force thought to be driving the accelerating expansion of the universe.
Scientists estimate that dark energy accounts for about 68 percent of the universe. Despite dominating the cosmic energy budget, researchers still do not know what it actually is or how it shapes the large-scale evolution of the cosmos.
A newly discovered supernova in the distant universe is now providing an important clue. The explosion occurred more than 10 billion years ago, meaning its light has been traveling through space for most of cosmic history before finally reaching Earth. The event was extraordinarily bright, and its light was amplified even further when it passed near a massive galaxy whose gravity acted like a natural lens.
A rare supernova reveals a new clue
“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,” explains Dr. Daniel Perley, a reader in astrophysics at Liverpool John Moores University.
In this case, a galaxy sits directly between Earth and the distant supernova. The galaxy’s gravity bends and distorts the light from the explosion as it travels toward us, producing a striking optical effect that holds valuable information for astronomers.
“We are seeing the light from this distant supernova split into multiple images, what we call ‘gravitationally lensed,’” explains Jacob Wise, a PhD student at the Astrophysics Research Institute, who first realized its significance.
Light’s varying paths to Earth
“When light is ‘lensed’, the different paths the light follows to get to Earth don’t all have the same length, so light moving along different paths takes variable amounts of time to reach us.”
Because supernovae can shine for months, astronomers are able to observe multiple images of the same explosion at the same time. Each image represents light that followed a different route through space and therefore corresponds to a slightly different moment in the supernova’s evolution.
“What’s exciting about that is that the amount of time difference between different images depends on the expansion rate of the universe,” added Dr. Perley.
The research team, working alongside collaborators from Caltech, Stockholm University, and several other institutions around the world, plans to measure these time delays very precisely. Those measurements could reveal how quickly the universe is expanding and help scientists understand the influence of dark energy on that expansion.
New calculation on the expansion of the Universe
Astronomers currently have two different measurements for the universe’s expansion rate, and they do not agree with each other. Perley believes this unusual supernova may help determine which value is correct.
He said: “Studies of afterglow of the Big Bang give one number for the so-called Hubble constant – the measurement of the expansion speed of the universe – while studies of nearby galaxies give a different number. Astronomers are calling this the Hubble Tension. Hence, studies of lensed supernovae could indicate which of these two numbers we should really believe.”
Global telescopes capture the event
The magnified supernova was so luminous that it could be detected even at its extreme distance using medium-sized ground-based telescopes. Early observations came from the Zwicky Transient Facility in California. Although that instrument first identified the explosion, it could not resolve the multiple images produced by gravitational lensing. The Liverpool Telescope in La Palma later captured those separate images, confirming that the event had been gravitationally lensed.
Further observations followed with some of the world’s most powerful instruments, including the Keck Telescopes in Hawaii, the Hubble Space Telescope, and the James Webb Space Telescope.
Added Jacob: “Our colleagues in Stockholm first noticed the supernova, but it was us who spotted that the light had been bent into multiple images.
“All the major observatories in the Northern Hemisphere, plus the space-based telescopes, have been looking at this but it was the Liverpool Telescope, run from LJMU, that got there first,” beamed Wise.
Reference: “Discovery of SN 2025wny: A Strongly Gravitationally Lensed Superluminous Supernova at z = 2.01” by Joel Johansson, Daniel A. Perley, Ariel Goobar, Jacob L. Wise, Yu-Jing Qin, Zoë McGrath, Steve Schulze, Cameron Lemon, Anjasha Gangopadhyay, Konstantinos Tsalapatas, Igor Andreoni, Eric C. Bellm, Joshua S. Bloom, Richard Dekany, Suhail Dhawan, Claes Fransson, Christoffer Fremling, Matthew J. Graham, Steven L. Groom, Daniel Gruen, Xander J. Hall, George Helou, Mansi Kasliwal, Russ R. Laher, Ragnhild Lunnan, Ashish A. Mahabal, Adam A. Miller, Edvard Mörtsell, Jakob Nordin, Jacob Osman Hjortlund, R. Michael Rich, Reed L. Riddle, Avinash Singh, Jesper Sollerman, Alice Townsend and Lin Yan, 5 December 2025, The Astrophysical Journal Letters.
DOI: 10.3847/2041-8213/ae1d61
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