paper

An Improved Method to Measure the Cosmic Curvature

arXiv:1611.00904 · doi:10.3847/1538-4357/aa674b

Abstract

In this paper, we propose an improved model-independent method to constrain the cosmic curvature by combining the most recent Hubble parameter and supernovae Ia (SNe Ia) data. Based on the data, we first use the model-independent smoothing technique, Gaussian processes, to construct distance modulus , which is susceptible to the cosmic curvature parameter . In contrary to previous studies, the light-curve fitting parameters, which account for distance estimation of SN (), are set free to investigate whether has a dependence on them. By comparing to , we put limits on . Our results confirm that is independent of the SN light-curve parameters. Moreover, we show that the measured is in good agreement with zero cosmic curvature, implying that there is no significant deviation from a flat Universe at the current observational data level. We also test the influence of different samples and different Hubble constant values, finding that different samples do not present significant impact on the constraints. However, different priors can affect the constraints of in some degree. The prior of km gives a value of a little bit above confidence level away from 0, but km gives it below .

9 pages, 5 figures, 2 tables. Accepted for publication in ApJ

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