The Pantheon+ Analysis: Cosmological Constraints
Abstract
We present constraints on cosmological parameters from the Pantheon+ analysis of 1701 light curves of 1550 distinct Type Ia supernovae (SNe Ia) ranging in redshift from z=0.001 to 2.26. This work features an increased sample size, increased redshift span, and improved treatment of systematic uncertainties in comparison to the original Pantheon analysis and results in a factor of two improvement in cosmological constraining power. For a Flat model, we find M=0.3340.018 from SNe Ia alone. For a Flatw0CDM model, we measure w0=-0.900.14 from SNe Ia alone, H0=73.51.1 km s-1 Mpc-1 when including the Cepheid host distances and covariance (SH0ES), and w0=-0.978+0.024-0.031 when combining the SN likelihood with constraints from the cosmic microwave background (CMB) and baryon acoustic oscillations (BAO); both w0 values are consistent with a cosmological constant. We also present the most precise measurements to date on the evolution of dark energy in a Flatw0waCDM universe, and measure wa=-0.1+0.9-2.0 from Pantheon+ alone, H0=73.31.1 km s-1 Mpc-1 when including SH0ES, and wa=-0.65+0.28-0.32 when combining Pantheon+ with CMB and BAO data. Finally, we find that systematic uncertainties in the use of SNe Ia along the distance ladder comprise less than one third of the total uncertainty in the measurement of H0 and cannot explain the present "Hubble tension" between local measurements and early-Universe predictions from the cosmological model.