Supernova Time Dilation in Hybrid Expansion-Tired-Light Cosmologies

Abstract

Dark Energy Survey has shown that the emission light curve widths $\Delta t_{\mathrm{em}}$ of supernovae increase to $\Delta t_{\mathrm{obs}}$, obeying $\Delta t_{\mathrm{obs}}/\Delta t_{\mathrm{em}}=(1+z{)}^b$ with $b=1.003\pm 0.011$, excluding a nondilating redshift. We test hybrid models with $1+z=(1+z_p)(1+z_t)$ and the phenomenological stretch $(1+z_p)R(z)$, where $z_p$ is the redshift associated with the expanding parent universe cosmology, $z_t$ is a tired-light (TL) contribution, and $R$ is the hybrid-to-parent lookback-time ratio. At $z=1$, $R$ and $1+z_t$ differ by $1.3\%$ for CCC+TL and $0.5\%$ for $\Lambda$CDM+TL, and their 95\% bands overlap the observed relation. This compatibility shows that the observations do not exclude the hybrid models, only fully nonexpanding ones.

3 pages, 1 figure, and 1 table. Comments invited