Vincenzi, M. and Kessler, R. and Shah, P. and Lee, J. and Davis, T.M. and Scolnic, D. and Armstrong, P. and Brout, D. and Camilleri, R. and Chen, R. and Galbany, L. and Lidman, C. and Möller, A. and Popovic, B. and Rose, B. and Sako, M. and Sánchez, B.O. and Smith, M. and Sullivan, M. and Wiseman, P. and Abbott, T.M.C. and Aguena, M. and Allam, S. and Andrade-Oliveira, F. and Bocquet, S. and Brooks, D. and Rosell, A.C. and Carretero, J. and da Costa, L.N. and Pereira, M.E.S. and Diehl, H.T. and Doel, P. and Everett, S. and Flaugher, B. and Frieman, J. and García-Bellido, J. and Gaztanaga, E. and Gruen, D. and Gruendl, R.A. and Gutierrez, G. and Hinton, S.R. and Hollowood, D.L. and Honscheid, K. and James, D.J. and Kuehn, K. and Lahav, O. and Lee, S. and Marshall, J.L. and Mena-Fernández, J. and Miquel, R. and Muir, J. and Myles, J. and Palmese, A. and Malagón, A.A.P. and Porredon, A. and Samuroff, S. and Sanchez, E. and Cid, D.S. and Sevilla-Noarbe, I. and Suchyta, E. and Tarle, G. and To, C. and Tucker, D.L. and Vikram, V. and Walker, A.R. and Weaverdyck, N. and Weller, J. (2025) Comparing the DES-SN5YR and Pantheon+ SN cosmology analyses : investigation based on ‘evolving dark energy or supernovae systematics’? Monthly Notices of the Royal Astronomical Society, 541 (3). pp. 2585-2593. ISSN 0035-8711
Full text not available from this repository.Abstract
Recent cosmological analyses measuring distances of type Ia supernovae (SNe Ia) and baryon acoustic oscillations (BAO) have all given similar hints at time-evolving dark energy. To examine whether underestimated SN Ia systematics might be driving these results, Efstathiou (2025) compared overlapping SN events between Pantheon+ and DES-SN5YR (20 per cent SNe are in common), and reported evidence for an ∼0.04 mag offset between the low- and high-redshift distance measurements of this subsample of events. If this offset is arbitrarily subtracted from the entire DES-SN5YR sample, the preference for evolving dark energy is reduced. In this paper, we show that this offset is mostly due to different corrections for Malmquist bias between the two samples; therefore, an object-to-object comparison can be misleading. Malmquist bias corrections differ between the two analyses for several reasons. First, DES-SN5YR used an improved model of SN Ia luminosity scatter compared to Pantheon+ but the associated scatter-model uncertainties are included in the error budget. Secondly, improvements in host mass estimates in DES-SN5YR also affected SN standardized magnitudes and their bias corrections. Thirdly, and most importantly, the selection functions of the two compilations are significantly different, hence the inferred Malmquist bias corrections. Even if the original scatter model and host properties from Pantheon+ are used instead, the evidence for evolving dark energy from CMB, DESI BAO Year 1 and DES-SN5YR is only reduced from 3.9σ to 3.3σ, consistent with the error budget. Finally, in this investigation, we identify an underestimated systematic uncertainty related to host galaxy property uncertainties, which could increase the final DES-SN5YR error budget by 3 per cent. In conclusion, we confirm the validity of the published DES-SN5YR results.