A recent study has proposed a new model for understanding the universe’s accelerating expansion, focusing on the relationship between star formation and cosmic acceleration. The research, published in Physical Review Letters, involved scientists from Arizona State University (ASU), including Regents Professor Rogier Windhorst and Assistant Research Scientist Kevin Croker of the School of Earth and Space Exploration.
The Dark Energy Spectroscopic Instrument (DESI), located at Kitt Peak National Observatory in southern Arizona, played a key role in this work. DESI uses 5,000 robotic devices to collect light from millions of galaxies. Its detailed maps allowed researchers to examine how dark energy might be connected to the life cycle of stars.
According to the cosmologically coupled black hole (CCBH) model introduced by Croker and University of Hawaiʻi Associate Professor Duncan Farrah about five years ago, as stars collapse into black holes, some of their mass is converted into dark energy. This approach helps explain why dark energy’s influence appears to change over time and addresses gaps in accounting for all matter in the universe, particularly regarding neutrinos.
Neutrinos are extremely abundant but difficult to measure due to their weak interactions with matter. The standard model for dark energy did not account for enough neutrino presence, leading to inconsistencies when compared with observations.
“The data would suggest that the neutrino mass is negative and that, of course, is likely unphysical,” said Windhorst.
If black holes have been converting stellar material into dark energy for billions of years as described by the CCBH model, it would mean less matter remains in the universe today than previously thought. This adjustment could resolve discrepancies related to missing neutrino mass.
Croker noted his experience working with DESI: “Working with DESI on the three-year data, it’s been a game changer,” he said. “You’ve got some of the sharpest and most creative researchers in the field lending their hands and hearts. It’s an absolute privilege.”
The CCBH hypothesis also offers potential solutions for other unresolved issues in cosmology, such as varying measurements of the Hubble constant—the rate at which the universe expands—by allowing dark energy to change as stars evolve rather than remain static.
DESI is led by Lawrence Berkeley National Laboratory with support from agencies including the U.S. Department of Energy Office of Science and National Science Foundation along with contributions from more than 70 institutions worldwide.
