Measurements of soft and intermediate image photons from hot and dense matter at RHIC-PHENIX Original Research Article

The measurements of direct photons in View the MathML source for p+p and Au+Au collisions have been made through the virtual photon method at PHENIX. The fraction of the direct γ∗ component to the inclusive e+e− yield is determined by a shape analysis using the e+e− mass spectra in View the MathML source for View the MathML source. The real direct photon spectra in p+p and Au+Au collisions are obtained from the virtual direct photon fractions, and a significant excess over a binary-scaled p+p result is seen in Au+Au collisions. Hydrodynamical models which reproduce the Au+Au result indicate the initial temperature of the matter is higher than the critical temperature of QGP. The d+Au data taken in 2008 are promising to evaluate the contribution of the nuclear effects due to its large statistics.