Hint towards inconsistency between BAO and Supernovae Dataset: The Evidence of Redshift Evolving Dark Energy from DESI DR2 is Absent
Samsuzzaman Afroz, Suvodip Mukherjee
arXiv:2504.16868v2 Announce Type: replace
Abstract: The combination of independent cosmological datasets is a route towards precise and accurate inference of cosmological parameters if these observations are free from systematic effects. However, unknown systematics in different datasets can lead to biased inference of cosmological parameters. In this work, we test the consistency of two independent tracers of low-redshift cosmic expansion, namely the supernova dataset from Pantheon$+$ and the BAO dataset from DESI DR2, using the distance duality relation, a cornerstone of cosmology within General Relativity. We find that these datasets violate the distance duality relation and show a redshift-dependent signature, hinting at unaccounted physical effects or observational artifacts. This effect mimics a redshift-evolving dark energy scenario when Pantheon$+$ and DESI datasets are combined without accounting for this inconsistency. Accounting for this effect in the likelihood refutes the previous claim of evidence for non-cosmological constant dark energy from DESI DR2, yielding results consistent with a cosmological constant with $w_0= -0.92pm 0.08$ and $w_a= -0.49^{+0.33}_{-0.36}$. This is further supported by an increased Bayes factor at ($w_0 = -1$, $w_a = 0$) when the inconsistency is accounted for. This indicates that current conclusions from DESI DR2 combined with Pantheon$+$ likely arise from combining inconsistent datasets, leading to precise but inaccurate inference of cosmological parameters. Future tests of consistency between cosmological datasets will be essential for robust inference and for identifying unaccounted physical effects or observational artifacts.[Abridged]arXiv:2504.16868v2 Announce Type: replace
Abstract: The combination of independent cosmological datasets is a route towards precise and accurate inference of cosmological parameters if these observations are free from systematic effects. However, unknown systematics in different datasets can lead to biased inference of cosmological parameters. In this work, we test the consistency of two independent tracers of low-redshift cosmic expansion, namely the supernova dataset from Pantheon$+$ and the BAO dataset from DESI DR2, using the distance duality relation, a cornerstone of cosmology within General Relativity. We find that these datasets violate the distance duality relation and show a redshift-dependent signature, hinting at unaccounted physical effects or observational artifacts. This effect mimics a redshift-evolving dark energy scenario when Pantheon$+$ and DESI datasets are combined without accounting for this inconsistency. Accounting for this effect in the likelihood refutes the previous claim of evidence for non-cosmological constant dark energy from DESI DR2, yielding results consistent with a cosmological constant with $w_0= -0.92pm 0.08$ and $w_a= -0.49^{+0.33}_{-0.36}$. This is further supported by an increased Bayes factor at ($w_0 = -1$, $w_a = 0$) when the inconsistency is accounted for. This indicates that current conclusions from DESI DR2 combined with Pantheon$+$ likely arise from combining inconsistent datasets, leading to precise but inaccurate inference of cosmological parameters. Future tests of consistency between cosmological datasets will be essential for robust inference and for identifying unaccounted physical effects or observational artifacts.[Abridged]

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