Essential to the study of heavy ion collisions are probes that are produced in the collision itself. Photons are a very useful probe of the collisions, since they escape the fireball virtually unmodified and carry with them information about the environment in which it was produced. Recent interest in low momentum direct photons has increased, due to the onset of the “thermal photon puzzle” and the apparent inability for typical models to explain both a large direct photon yield excess and large azimuthal production asymmetry (v2) at low momentum measured by PHENIX.
