Pantheon+ constraints on dark energy and modified gravity: An evidence of dynamical dark energy

We use the latest Type Ia supernovae sample Pantheon+ to explore new physics on cosmic scales. Specifically, in light of this new sample, we constrain the interacting dark energy and Hu-Sawicki $f(R)$ gravity models and employ the model-independent Gaussian processes to investigate whether there is an evidence of dark energy evolution. We find that Pantheon+ alone just gives weak constraints. However, a data combination of Pantheon+ with cosmic microwave background, baryon acoustic oscillations and cosmic chronometers gives a strong constraint on the modified matter expansion rate $\epsilon=0.048\pm0.026$, which indicates that the momentum may transfer from dark energy to dark matter in the dark sector of the universe at the $1.85\,\sigma$ confidence level. In the meantime, we obtain a very tight constraint on the deviation from general relativity $\log_{10} f_{R0}< -6.32$ at the $2\,\sigma$ confidence level. Interestingly, when combining Pantheon+ with cosmic chronometers and cosmic microwave background data, we find a quintessence-like dark energy signal beyond the $2\,\sigma$ confidence level in the redshift range $z\in[0.70,1.05]$. This implies the nature of dark energy may actually be dynamical.