J un 2 00 9 Elliptic flow of thermal photons at midrapidity in Au + Au collisions at √ s NN = 200 GeV

The elliptic flowv2 of thermal photons at midrapidity in Au +Au collisions at √ sNN = 200GeV is predicted, based on three-dimensional ideal hydrodynam ics. Because of the interplay between the asymmetry and the strength of the transverse flow, the the rmal photonv2 reaches a maximum at pt ∼ 2GeV/c and thept-integratedv2 reaches a maximum at about 50% centrality. The ptintegratedv2 is very sensitive to the lower limit of the integral but not se n itive to the upper limit due to the rapid decrease in the spectrum of the transverse mo mentum.