Astronomers have combined 2,884 Type Ia supernovae — which are used to measure cosmic distances — with cosmic microwave background and galaxy-mapping data, deepening cracks in the standard ‘cosmological constant’ model.
This is an artist’s concept of a Type Ia supernova exploding in the intergalactic space between galaxies within a galactic cluster. Image credit: Alex Parker / NASA / SDSS.
“Our project sets a new global benchmark in supernova cosmology and provides the clearest picture yet of how the Universe has expanded over time,” said University of Queensland Ph.D. candidate Ryan Camilleri.
“We’ve rebuilt three decades of astronomical observations into a single, consistent framework.”
“We combined our data with other cosmic measurements including relic light from the Big Bang and maps of how galaxies are distributed through space.”
“Instead of confirming the standard model of cosmology which assumes dark energy is fixed and unchanging, we have more evidence that dark energy may change over time.”
The dataset combines historic measurements with data from the Dark Energy Survey (DES) published in 2024.
To unify the information, Camilleri and colleagues also reanalyzed older observations.
“Over the years we’ve learned a lot more about how supernovae behave so we’ve been able to go back and apply that improved understanding to older data,” he said.
“Extensive work has been done to link observations from different telescopes with different capacities and take into account issues such as cosmic dust and galaxy mass which can affect the light coming from a supernova.”
“We also incorporated more subtle effects such as gravitational lensing, which is the bending and magnification of light around large objects as it travels from a supernova to Earth.”
“The dataset was an exciting step towards understanding what dark energy could be,” said University of Queensland’s Professor Tamara Davis.
“Our supernova data from DES in 2024 first showed hints that dark energy may be time varying, and this new compilation also sees a deviation from the standard model although in a slightly different direction.”
“Similarly results from the Dark Energy Spectroscopic Instrument (DESI) found hints of variations in dark energy in its surveys of relic sound waves from the early Universe.”
“So, two completely independent measurements have found hints of time variation in dark energy, challenging the standard model that dark energy doesn’t change.”
“All of this research may also hold the clue to explain how gravity and quantum physics fit together.”
“We know these two theories are each immensely successful in their own realms, so if we can figure out how to put them together that would be a huge step in theoretical physics.”
_____
J. Lee et al. 2026. Supernovae Unite: Host-Galaxy Mass Measurements of Type Ia Supernovae and Their Impact on Cosmology. arXiv: 2609.05321
Ryan Camilleri et al. 2026. Supernovae Unite: Combining Pantheon+ and DES-SN5YR. arXiv: 2609.05053
