Supernova Time Dilation in Hybrid Expansion-Tired-Light Cosmologies

Dark Energy Survey has shown that the emission light curve widths $\mathrm{\Delta }{t}_{\mathrm{e}\mathrm{m}}$ of supernovae increase to $\mathrm{\Delta }{t}_{\mathrm{o}\mathrm{b}\mathrm{s}}$, obeying $\mathrm{\Delta }{t}_{\mathrm{o}\mathrm{b}\mathrm{s}}\mathrm{/}\mathrm{\Delta }{t}_{\mathrm{e}\mathrm{m}}=(1+z{)}^b$ 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 $1.3\mathrm{\%}$ for CCC+TL and $0.5\mathrm{\%}$ for $\mathrm{\Lambda }$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.