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arXiv · 1812.03623

Model Independent Expansion History from Supernovae: Cosmology versus Systematics

Benjamin L'Huillier·Arman Shafieloo·Eric V. Linder·Alex G. Kim
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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 $Λ$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 $Λ$CDM, 2) supernovae property evolution, and 3) survey selection effects. The strong (and theoretically problematic) deviations at $z\gtrsim1$ vanish and good consistency with $Λ$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 $Λ$CDM is striking, $χ^2$ 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.

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Benjamin L'Huillier, Arman Shafieloo, Eric V. Linder, Alex G. Kim. 2019-03-03. Model Independent Expansion History from Supernovae: Cosmology versus Systematics. https://doi.org/10.1093/mnras%2Fstz589

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