  Starlight in the Universe impedes the passage of high energy (e.g. TeV) gamma
rays due to positron-electron pair production. The history of this stellar
radiation field depends upon observations of star formation rate which
themselves can only be interpreted in the context of a particular cosmology.
For different equations of state of dark energy, the star formation rate data
suggests a different density of stellar photons at a particular redshift and a
different probability of arrival of gamma rays from distant sources. In this
work we aim to show that this effect can be used to constrain the equation of
state of dark energy. The current work is a proof of concept and we outline the
steps that would have to be taken to place the method in a rigorous statistical
framework which could then be combined with other more mature methods such as
fitting supernova luminosity distances.
