Largest supernova catalog adds evidence that dark energy may change over time
A team led by the University of Queensland combined 2,884 exploding white dwarf stars into one dataset, and it departs from cosmology's standard model.
A team led by researchers at the University of Queensland has built the largest collection of exploding white dwarf stars ever compiled, and the results suggest that dark energy may change over time, according to ScienceDaily. The report is based on materials provided by the university.
The dataset brings together observations of 2,884 Type Ia supernovae. Astronomers use these explosions to measure distances across the Universe, which lets them trace how its expansion has changed. Dark energy is the force responsible for the Universe's accelerating expansion.
“We've rebuilt 3 decades of astronomical observations into a single, consistent framework.”Ryan Camilleri, PhD candidate, University of Queensland
ScienceDaily reported that the team combined historical supernova measurements with Dark Energy Survey (DES) findings published in 2024. They reanalyzed older data using updated methods. They also corrected for differences between telescopes and for effects such as cosmic dust, galaxy mass and gravitational lensing, all of which can affect the light that reaches Earth from a supernova.
The supernova data was then combined with other cosmic measurements, including relic light from the Big Bang and maps of how galaxies are spread through space. Mr. Camilleri said that instead of confirming the standard model of cosmology, which assumes dark energy is fixed, the team found "more evidence that dark energy may change over time."
The finding matters because it challenges a central assumption of modern cosmology. Professor Tamara Davis, an astrophysicist, said the 2024 DES supernova data "first showed hints that dark energy may be time varying," and that the new compilation also departs from the standard model, "although in a slightly different direction."
Professor Davis pointed to separate results from the Dark Energy Spectroscopic Instrument (DESI), which also found hints of variation in dark energy. She said "2 completely independent measurements" now point that way. She added that the work may also help explain how gravity and quantum physics fit together.
Several questions remain open. The researchers describe their results as hints and evidence, not proof. ScienceDaily noted that the different measurements do not point to exactly the same departure from the standard model. The findings are posted on arXiv, and the report does not say whether they have been peer reviewed.
The team plans to grow the dataset as new observations arrive. One source will be the Dark Energy Bedrock All-Sky Supernova program (DEBASS), which is identifying hundreds of supernovae closer to Earth than those in DES. Those measurements will be used to test whether dark energy truly changes over time.
