Non-parametric reconstruction of dark energy and cosmic expansion from the Pantheon compilation of type Ia supernovae *

Abstract

Abstract The equation of state (EoS) of dark energy plays an important role in the evolution of the universe and has attracted considerable interest in the recent years. With the progress in observational technique, a precise constraint on the EoS of dark energy can be obtained. In this study, we reconstruct the EoS of dark energy and cosmic expansion using Gaussian processes (GP) from the most up-to-date Pantheon compilation of type Ia supernovae (SNe Ia), which consists of 1048 finely calibrated SNe Ia. The reconstructed EoS of dark energy has a large uncertainty owing to its dependence on the second-order derivative of the construction. Adding the direct measurements of Hubble parameters as an additional constraint on the first-order derivative can partially reduce the uncertainty; however, it is still not sufficiently precise to distinguish between the evolving and the constant dark energy. Moreover, the results heavily rely on the prior of the Hubble constant . The value inferred from SNe+ without prior is . Moreover, the matter density has a non-negligible effect on the reconstruction of dark energy. Therefore, more accurate determinations on and are required to tightly constrain the EoS of dark energy.