Rather surprisingly, it turns out that a certain type of supernova explosion (called “Type 1a” and associated with detonating white-dwarf stars) has a peak luminosity L that can be determined by studying the way its brightness subsequently declines. Astronomers can measure the peak fluxes F for a population of supernovae at a range of distances.
Calculate the flux measured at Earth for a given L as a function of the scale factor 0.3< a <1 at the time of emission for the following.

(a) An Einstein–de Sitter universe.

(b) A nonaccelerating universe with a ∝ t .

(c) Our standard model universe.