Elliptic flow of thermal photons and formation time of quark gluon plasma at RHIC

Abstract

We calculate the elliptic flow of thermal photons from Au+Au collisions at RHIC energies for a range of values for the formation time $\ddot{I}{„}_0$ but fixed entropy (or particle rapidity density). The results are found to be quite sensitive to $\ddot{I}{„}_0$. The $v_2$ for photons decreases as $\ddot{I}{„}_0$ decreases and admits a larger contribution from the QGP phase which has a smaller $v_2$. The elliptic flow coefficient for hadrons, on the other hand, is only marginally dependent on $\ddot{I}{„}_0$.

2 extra figures and discussion added. To appear in Physical Review C (Rapid Communication)