Is the expansion of universe accelerating or the Photons decelerating?

Astronomical observations of the cosmological red-shift are currently interpreted in terms of ‘expansion of universe’ and ‘accelerated-expansion of the universe’, at the rate of H0 c; here H0 is Hubble’s constant, and c is the speed of light. Whereas a straight-forward derivation presented here suggests that: rather it is the photon which is decelerating, at the rate of H0 c. Such a deceleration of photons can be caused by virtual electrons, positrons and pi-mesons, contained in the extra galactic quantum vacuum, because: they do have gravitational-acceleration of the same order as H0 c at their “surfaces”; or by decay of a photon into a lighter photon and a particle of mass h H0 / c2. Tired-light interpretations of the cosmological red-shift’ were so far considered as not compatible with the observations of ‘time-dilation of super-novae light-curves’; so in a paper titled: “Wave-theoretical insight into the relativistic ‘length-contraction’ and ‘time-dilation of super-novae light-curves’” (Tank, Hasmukh K. 2013), it has been already shown that any mechanism which can cause ‘cosmological red-shift’ will also cause ‘time-dilation of super-novae light-curves’. Therefore, we now need not to remain confined to the Big-Bang model of cosmology.