Model independent expansion history from supernovae: Cosmology versus systematics
Open Access Publications from the University of California

## Model independent expansion history from supernovae: Cosmology versus systematics

• Author(s): L’Huillier, Benjamin
• Shafieloo, Arman
• Linder, Eric V
• Kim, Alex G
• et al.

## Published Web Location

https://doi.org/10.1093/mnras/stz589
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.