Kavli Affiliate: George Efstathiou
| First 5 Authors: George Efstathiou, , , ,
| Summary:
Recent results from the Dark Energy Spectroscopic Instrument (DESI)
collaboration have been interpreted as evidence for evolving dark energy.
However, this interpretation is strongly dependent on which Type Ia supernova
(SN) sample is combined with DESI measurements of baryon acoustic oscillations
(BAO) and observations of the cosmic microwave background (CMB) radiation. The
strength of the evidence for evolving dark energy ranges from ~3.9 sigma for
the Dark Energy 5 year (DES5Y) SN sample to ~ 2.5 sigma for the Pantheon+
sample. Here I compare SN common to both the DES5Y and Pantheon+ compilations
finding evidence for an offset of ~0.04 mag. between low and high redshifts.
Correcting for this offset brings the DES5Y sample into very good agreement
with the Planck LCDM cosmology. Given that most of the parameter range favoured
by the uncorrected DES5Y sample is discrepant with many other cosmological
datasets, I conclude that the evidence for evolving dark energy is most likely
a result of systematics in the DES5Y sample.
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