Generalizing the Hubble constant determination including curvature and dynamical dark energy

Abstract

We determine the Hubble constant H ₀ using two calibrator samples of type Ia supernovae (SNe Ia). We extend the well-consolidated procedure involving cosmographic series by including spatial curvature and we also utilize a different approach based on the Bézier interpolation curve accounting for the spatial curvature too. While the usual cosmographic approach assumes a ΛCDM background cosmology to fix some parameters, the Bézier approach is more general – thus, also accounts for possible dark energy models departing from the pure cosmological constant – and it is predictive also at higher redshifts. Albeit the effects of curvature and/or dynamical dark energy, leading to a decrease of the value of H ₀ by a 0.4 %, cannot be completely disentangled and a priori excluded, the main reason behind the reduced tension between Cepheid and cosmic microwave background based determinations of H ₀ is due to the calibration of SNe Ia. In conclusion, it cannot be excluded that in the future refined analyses will eventually further alleviate the current tension.