Strong evidence for an accelerating universe

A recent analysis of the Supernova Ia data claims a ‘marginal’ ($\sim 3\sigma$) evidence for a cosmic acceleration. This result has been complemented with a non-accelerating $R_h=ct$ cosmology, which was presented as a valid alternative to the $\mathrm{\Lambda }$CDM model. In this paper, we use the same analysis to show that a non-marginal evidence for acceleration is actually found. We compare the standard Friedmann models to the $R_h=ct$ cosmology by complementing SN Ia data with the Baryon Acoustic Oscillations, Gamma Ray Bursts and Observational Hubble datasets. We also study the power-law model which is a functional generalisation of $R_h=ct$. We find that the evidence for late-time acceleration is beyond refutable at a 4.56$\sigma$ confidence level from SN Ia data alone, and at an even stronger confidence level ($5.38\sigma$) from our joint analysis. Also, the non-accelerating $R_h=ct$ model fails to statistically compare with the $\mathrm{\Lambda }$CDM having a $\mathrm{\Delta }(\text{AIC})\sim 30$.