The Pantheon plus Analysis: Cosmological Constraints

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 from the addition of multiple cross-calibrated photometric systems of SNe covering an increased redshift span, and improved treatments of systematic uncertainties in comparison to the original Pantheon analysis, which together result in a factor of 2 improvement in cosmological constraining power. For a flat ACDM model, we find Omega(M) = 0.334 +/- 0.018 from SNe Ia alone. For a flat w(0)CDM model, we measure w(0) = -0.90 +/- 0.14 from SNe Ia alone, H-0 = 73.5 +/- 1.1 km s(-1) Mpc(-1 )when including the Cepheid host distances and covariance (SHOES), and w(0) = -0.978(-0.031)(+0.024) when combining the SN likelihood with Planck constraints from the cosmic microwave background (CMB) and baryon acoustic oscillations (BAO); both w(0) values are consistent with a cosmological constant. We also present the most precise measurements to date on the evolution of dark energy in a flat w(0)w(a)CDM universe, and measure w(a) = -0.1(-2.0)(+0.9) from Pantheon+ SNe Ia alone, H-0 = 73.3 +/- 1.1 km s(-1) Mpc(-1) when including SHOES Cepheid distances, and w(a) = -0.65(-0.32)(+0.28) when combining Pantheon+ SNe Ia 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 H-0 and cannot explain the present Hubble tension between local measurements and early universe predictions from the cosmological model.

Automated summary

This study presents constraints on cosmological parameters based on 1701 light curves of 1550 distinct Type Ia supernovae. By increasing the sample size, improving systematic uncertainty treatments, and adding cross-calibrated photometric systems, the cosmological constraining power has been significantly improved. The results indicate a consistent cosmological constant and provide precise measurements on the evolution of dark energy.