Title: Measurement of soft photon collective flow in $\sqrt{s_{NN}}$ = 200GeV Au+Au collisions at RHIC-PHENIX
Abstract: Direct photons have been measured to investigate the properties of quark-gluon plasma because they are very good probes.Third order azimuthal anisotropy (v 3 ) of direct photon is measured at PHENIX experiment.It is found that the magnitude of direct photon v 3 are comparable to that of neutral pion v 3 as already measured for direct photon v 2 .It could suggest that photons are mainly originated from late stage where the medium itself has large v n .Recently, photons converting e + e -pairs at materials are measured and it extend lower limit down to 400 GeV/c.The photon v n is compared with theoretical models and models including photons generating from hadron phase relatively describe experimental measurement.Measurement of photon v 3 helps to understand photon production mechanism.