Exploring the cosmological consequences of JLA supernova data with improved flux-averaging technique

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In this work, we explore the cosmological consequences of the "Joint Light-curve Analysis" (JLA) supernova (SN) data by using an improved flux-averaging (FA) technique, in which only the type Ia supernovae (SNe Ia) at high redshift are flux-averaged.

• Adopting the criterion of figure of Merit (FoM) and considering six dark energy (DE) parameterizations, we search the best FA recipe that gives the tightest DE constraints in the $(z_{cut}, \Delta z)$ plane, where $z_{cut}$ and $\Delta z$ are redshift cut-off and redshift interval of FA, respectively.
• Then, based on the best FA recipe obtained, we discuss the impacts of varying $z_{cut}$ and varying $\Delta z$, revisit the evolution of SN color luminosity parameter $\beta$, and study the effects of adopting different FA recipe on parameter estimation.
• We find that: (1) The best FA recipe is $(z_{cut} = 0.6, \Delta z=0.06)$, which is insensitive to a specific DE parameterization.