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

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

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 ΛCDM cosmology. Strong deviations are allowed by the data at z ≳ 1 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 ΛCDM, 2) supernovae property evolution, and 3) survey selection effects. The strong (and theoretically problematic) deviations at z ≳ 1 vanish and good consistency with ΛCDM 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 ΛCDM is striking, χ2 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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