Implications for dark energy of cosmic transparency in light of DESI data

Implications for dark energy of cosmic transparency in light of DESI data
S. Dhawan, E. M"ortsell
arXiv:2506.22599v1 Announce Type: new
Abstract: The distance duality relation (DDR) between luminosity and angular diameter distances holds if gravity is described by a metric theory and the universe is transparent. Recent cosmological inferences using Type Ia supernovae (SNe~Ia), baryon acoustic oscillation (BAO) and the cosmic microwave background (CMB) observations have suggested that dark energy may evolve in time. We test how the assumption of distance duality impacts dark energy inference. Marginalizing over the absolute SNe~Ia luminosity, we find no deviation from the DDR, independent of the SN~Ia compilation used, or the assumed dark energy model. This corresponds a maximum deviation in the SN~Ia luminosity of $Delta m sim 0.05$ mag at the highest redshift. Allowing for deviations in the DDR increases the errors in the dark energy equation of state parameters (EoS) by 30-50$%$. For the Pantheon+ compilation the constraints on dark energy are within $2sigma$ of $Lambda$CDM when applying a more realistic minimum redshift cut $z_{rm min} >0.023$. We constrain possible physical scenarios that can impact cosmic transparency, specifically photon-axion mixing and the presence of (gray) intergalactic (IG) dust, in the latter case limiting the dust density to $Omega_{rm dust}arXiv:2506.22599v1 Announce Type: new
Abstract: The distance duality relation (DDR) between luminosity and angular diameter distances holds if gravity is described by a metric theory and the universe is transparent. Recent cosmological inferences using Type Ia supernovae (SNe~Ia), baryon acoustic oscillation (BAO) and the cosmic microwave background (CMB) observations have suggested that dark energy may evolve in time. We test how the assumption of distance duality impacts dark energy inference. Marginalizing over the absolute SNe~Ia luminosity, we find no deviation from the DDR, independent of the SN~Ia compilation used, or the assumed dark energy model. This corresponds a maximum deviation in the SN~Ia luminosity of $Delta m sim 0.05$ mag at the highest redshift. Allowing for deviations in the DDR increases the errors in the dark energy equation of state parameters (EoS) by 30-50$%$. For the Pantheon+ compilation the constraints on dark energy are within $2sigma$ of $Lambda$CDM when applying a more realistic minimum redshift cut $z_{rm min} >0.023$. We constrain possible physical scenarios that can impact cosmic transparency, specifically photon-axion mixing and the presence of (gray) intergalactic (IG) dust, in the latter case limiting the dust density to $Omega_{rm dust}