Key points
- 30 years of astronomical observations have been combined into a single dataset.
- Historic information about supernovae was reanalysed using modern techniques.
- Researchers say the dataset provides more evidence that dark energy may not be constant but instead by changing over time.
The most comprehensive catalogue of exploding white dwarf stars ever assembled has revealed new clues about dark energy, the mysterious force driving the universe’s accelerating expansion.
Researchers at The University of Queensland’s School of Mathematics and Physics have led a global effort to compile a dataset that contains information on 2,884 Type Ia supernovae which are used to measure cosmic distances.
PhD candidate Ryan Camilleri said the project sets a new global benchmark in supernova cosmology and provides the clearest picture yet of how the universe has expanded over time.
“We’ve rebuilt 3 decades of astronomical observations into a single, consistent framework,” Mr Camilleri said.
“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, older observations were reanalysed using modern techniques.
“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,” Mr Camilleri 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.”
Astrophysicist Professor Tamara Davis said the dataset was an exciting step towards understanding what dark energy could be.
“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,” Professor Davis said.
“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, 2 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 2 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.”
Future surveys will be added to the data, including from the Dark Energy Bedrock All-Sky Supernova program (DEBASS) which is detecting hundreds more supernovae closer to Earth than the DES survey.
Read the cosmology results on arXiv here , and the host galaxy mass measurements on arXiv here .
Collaboration and acknowledgements
The results arise from the efforts of hundreds of researchers over many decades including people working with the Dark Energy Survey , Foundation Supernova Survey, PanStarrs I, Sloan Digital Sky Survey, Supernova Legacy Survey, Carnegie Supernova Project, and the Center for Astrophysics supernova survey.
