The largest catalog of Type Ia supernovae assembled so far is giving astronomers a more detailed record of cosmic expansion. The results add to evidence that dark energy, the unknown component believed to drive that expansion, may evolve rather than remain constant.
Type Ia supernovae occur when white dwarf stars undergo thermonuclear explosions. Because their brightness can be standardized, astronomers use them as cosmic distance markers, comparing how bright they appear with how quickly their host galaxies are receding. Similar observations helped reveal the accelerating expansion of the universe in the late 1990s.
An international effort led by the University of Queensland’s School of Mathematics and Physics compiled measurements from 2,884 Type Ia supernovae. PhD candidate Ryan Camilleri said the collection establishes a new benchmark for supernova cosmology and provides the clearest reconstruction yet of how cosmic expansion has changed 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.”
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