The Pantheon+ Analysis: Cosmological Constraints (2202.04077v2)

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$\Lambda$CDM model, we find $\Omega_M=0.334\pm0.018$ from SNe Ia alone. For a Flat$w_0$CDM model, we measure $w_0=-0.90\pm0.14$ from SNe Ia alone, H$0=73.5\pm1.1$ km s$^{-1}$ Mpc$^{-1}$ when including the Cepheid host distances and covariance (SH0ES), and $w_0=-0.978^{+0.024}{-0.031}$ when combining the SN likelihood with constraints from the cosmic microwave background (CMB) and baryon acoustic oscillations (BAO); both $w_0$ 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$w_0w_a$CDM universe, and measure $w_a=-0.1^{+0.9}_{-2.0}$ from Pantheon+ alone, H$0=73.3\pm1.1$ km s$^{-1}$ Mpc$^{-1}$ when including SH0ES, and $w_a=-0.65^{+0.28}{-0.32}$ 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 H$_0$ and cannot explain the present "Hubble tension" between local measurements and early-Universe predictions from the cosmological model.

• The paper enhances cosmological constraints by analyzing 1701 light curves from 1550 Type Ia supernovae over a wide redshift range.
• The paper employs advanced cross-calibrated photometry and refined systematic treatments to double the constraining power compared to earlier analyses.
• The paper derives precise parameters under FlatΛCDM, FlatwCDM, and Flatw₀wₐCDM models, offering critical insights into the dynamics of dark energy and cosmic expansion.

Overview of the Pantheon+ Analysis: Cosmological Constraints

The paper "The Pantheon+ Analysis: Cosmological Constraints" presents an in-depth analysis of 1701 light curves from 1550 distinct Type Ia supernovae (SNe Ia), covering a redshift range from 0.001 to 2.26. This substantial dataset is used to yield improved constraints on cosmological parameters, building on prior work from the original Pantheon analysis. Core improvements include an expanded dataset, incorporation of advanced cross-calibrated photometric systems, and refined treatment of systematic uncertainties, resulting in a twofold enhancement in cosmological constraining power.

Key Findings

The analysis assesses several cosmological models, notably the Flat$\Lambda$CDM, Flat$w$CDM, and Flat$w_0w_a$CDM, offering critical insights into the energy dynamics of the universe:

• For a Flat$\Lambda$CDM model, the team's analysis of SNe Ia alone estimates $\Omega_M = 0.334$.
• Within a Flat$w$CDM framework, they report $w_0 = -0.90$ with $\Omega_M = +0.063$, indicating consistency with a cosmological constant.
• Incorporating Planck CMB and BAO data further refines $w_0$ to +0.024 in a Flat$w$CDM model, highlighting SNe Ia's ability to constrain dark energy models when joined with other cosmological markers.
• For the Flat$w_0w_a$CDM models, they assess the evolution of dark energy as $w_a = +0.9$ from supernovae alone, surveying both local and extensive cosmic scales.

Implications and Future Prospects

The findings present notable implications for both theoretical and applied cosmology. The research offers robust evidence in support of the ΛCDM model and aids in narrowing uncertainties surrounding dark energy's nature and influence. The improved precision in systematic methodology propels future constraints on the Hubble constant ($H_0$) and adds clarity to the prevailing "Hubble tension." Through meticulous calibration and systematic error reduction, this work sets a benchmark for upcoming surveys and analyses aiming to disentangle the complexities of cosmic expansion.

The Pantheon+ dataset's availability invites further scrutiny and comparative studies to validate and refine the analysis. As large-scale surveys such as the Dark Energy Survey (DES) and the Legacy Survey of Space and Time (LSST) evolve, the strategies framed here will be pivotal in enhancing the resolution of cosmological parameters. Beyond extending existing frameworks, this analysis encourages a new wave of interdisciplinary research, integrating astrophysical observations with cutting-edge data science techniques, ultimately enriching our understanding of the universe's accelerated expansion.