The Dark Energy Survey supernova program: a reanalysis of cosmology results and evidence for evolving dark energy with an updated Type Ia supernova calibration
B Popovic, P Shah, W. D. Kenworthy, R Kessler, T. M. Davis, A. Goobar, D. Scolnic, M. Vincenzi, P. Wiseman, R Chen, E Charleton, M. Acevedo, P. Armstrong, Benjamin M. Boyd, D Brout, R Camilleri, J Frieman, L. Galbany, Matthew Grayling, L Kelsey, Brian E. J. Rose, Blanca de Vega Sánchez, S. Lee, A. Möller, M Smith, M Sullivan, Nikolaos Shiamtanis, A. Alarcon, S. Allam, F. Andrade-Oliveira, S. Àvila, D Bacon, J. Blazek, S. Bocquet, David J. Brooks, D. L. Burke, A. Carnero Rosell, J. Carretero, R. Cawthon, L. N. da Costa, Maria Estér Pereira, H. T. Diehl, Scott Dodelson, P. Doel, S Everett, C. Frohmaier, J. García-Bellido, D Gruen, G Gutierrez, K. Herner, S. R. Hinton, D. L. Hollowood, Klaus Honscheid, Dragan Huterer, D.J James, N Jeffrey, K. Kuehn, O Lahav, S Lee, C. Lidman, J.L Marshall, J. Mena-Fernández, F. Menanteau, R Miquel, J. Muir, J. Myles, R. L. C. Ogando, M. Paterno, A A Plazas Malagón, A. Porredon, J. Prat, R. C. Nichol, A. K. Romer, A. Roodman, E. Sanchez, D Sanchez Cid, I. Sevilla-Noarbe, E. Suchyta, M. E. C. Swanson, C. To, D. L. Tucker, A. R. Walker, N. Weaverdyck, M Aguena
Abstract
ABSTRACT 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 $\sim$1600 likely Type Ia SNe from DES and $\sim$200 low-redshift SNe from other surveys. With DES-Dovekie, we obtain $\Omega _{\rm m} = 0.330 \pm 0.015$ in flat Lambda-cold dark matter ($\Lambda$CDM) which changes $\Omega _{\rm m}$ by $-0.022$ 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 $w_0 w_a$CDM cosmology, we find $w_0 = -0.803 \pm 0.054$ and $w_a = -0.72 \pm 0.21$. Our results hold a significance of $3.2\sigma$, reduced from $4.2\sigma$ 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 $w_0 w_a$CDM model. Using generally accepted thresholds for model preference, our updated data exhibits only a weak preference for evolving dark energy.