Elsewhere, I am having a few slightly heated discussions about how to calculate the Luminosity distance as a function of z, for an alternative cosmology.

The Wikipedia page "Luminosity distance - Wikipedia, the free encyclopedia" gets a bit complicated very quickly for the BBT version.

I was assuming that if I have a function distance(z) and function photonRate(z) (photon rate decreases with z)

Then Luminosity distance is just: distance(z)/photonRate(z)

:confused: