Photons from Quark and Hadron Phases in Au + Au Collisions

Based on a relativistic hydrodynamic model describing the evolution of the chemically equilibrating quark--gluon plasma system with finite baryon density in a 3+1-dimensional spacetime, we compute photons from the quark phase, hadronic phase and initial non-thermal contributions. It is found that due to the effects of the initial quark chemical potential, chemical equilibration and rapid expansion of the system, the photon yield of the quark--gluon plasma is strongly suppressed, and photons from hadronic matter and initial non-thermal contributions almost reproduce experimental data.