  Measurements indicate that the centrality dependence of the direct photon
multiplicity scales approximately with the number of binary nucleon collisions.
Importantly, these same measurements suggest that this scaling does not depend
on the cutoff used to define the photon multiplicity. In this work we provide a
theoretical perspective on these observations. We emphasize the importance of
stronger experimental constraints, in particular for the cutoff independence of
the centrality scaling. We highlight the importance of revisiting theoretical
studies of jet-medium photons and of medium-modified prompt photons to clarify
their contribution to the direct photon multiplicity, as well as the magnitude
and direction of their momentum anisotropy.
