# Model Independent Expansion History from Supernovae: Cosmology versus Systematics

## TL;DR

This study uses a model-independent approach to analyze supernova data, revealing apparent deviations from standard cosmology at high redshifts that can be mitigated with simple corrections, though statistical significance remains uncertain.

## Contribution

It demonstrates that apparent high-redshift deviations from $ ext{Lambda}$CDM in supernova data can be explained by simple corrections, emphasizing the importance of model-independent analysis.

## Key findings

- Deviations at $z extgreater1$ can be reduced with a linear correction.
- Model-independent methods do not find statistically significant deviations.
- Corrected data remains consistent with $ ext{Lambda}$CDM.

## Abstract

We examine the Pantheon supernovae distance data compilation in a model independent analysis to test the validity of cosmic history reconstructions beyond the concordance $\Lambda$CDM cosmology. Strong deviations are allowed by the data at $z\gtrsim1$ in the reconstructed Hubble parameter, $Om$ diagnostic, and dark energy equation of state. We explore three interpretations: 1) possibility of the true cosmology being far from $\Lambda$CDM, 2) supernovae property evolution, and 3) survey selection effects. The strong (and theoretically problematic) deviations at $z\gtrsim1$ vanish and good consistency with $\Lambda$CDM is found with a simple Malmquist-like linear correction. The adjusted data is robust against the model independent iterative smoothing reconstruction. However, we caution that while by eye the original deviation from $\Lambda$CDM is striking, $\chi^2$ tests do not show the extra linear correction parameter is statistically significant, and a model-independent Gaussian Process regression does not find significant evidence for the need for correction at high-redshifts.