The Dark Energy Survey supernova program: a reanalysis of cosmology results and evidence for evolving dark energy with an updated Type Ia supernova calibration

Journal article

We present improved cosmological constraints from a re-analysis of the Dark Energy Survey (DES) 5-year sample of Type Ia supernovae (DES-SN5YR). This re-analysis includes an improved photometric cross-calibration, recent white dwarf observations to cross-calibrate between DES and low-redshift surveys, retraining the salt3 light-curve model and fixing a numerical approximation in the host-galaxy colour law. Our fully recalibrated sample, which we call DES-Dovekie, comprises 1600 likely Type Ia SNe from DES and 200 low-redshift SNe from other surveys. With DES-Dovekie, we obtain in flat Lambda-cold dark matter (CDM) which changes by compared to DES-SN5YR. Combining DES-Dovekie with cosmic microwave background data from Planck, Atacama Cosmology Telescope, and South Pole Telescope and the DESI DR2 measurements in a flat CDM cosmology, we find and . Our results hold a significance of , reduced from for DES-SN5YR, to reject the null hypothesis that the data are compatible with the cosmological constant. This significance is equivalent to a Bayesian model preference odds of approximately 5:1 in favour of the flat CDM model. Using generally accepted thresholds for model preference, our updated data exhibits only a weak preference for evolving dark energy.

Authors: Popovic, B; Shah, P; Kenworthy, WD; Kessler, R; Davis, TM

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Oxford University Press
• Journal: Monthly Notices of the Royal Astronomical Society
• Volume: 548
• Issue: 4
• Pages: stag632
• Article number: stag632
• Publication date: 2026-04-14
• Acceptance date: 2026-03-20
• DOI: 10.1093/mnras/stag632
• EISSN: 1365-2966
• ISSN: 0035-8711
• Language: English
• Keywords: transients: supernovae; dark energy