Is early thermalization achieved only near midrapidity in Au + Au collisions at sNN=130 GeV?

Abstract

The pseudorapidity dependence of elliptic flow in Au+Au collisions at $130A \mathrm{GeV}$ is studied within a full three-dimensional hydrodynamic model in the light-cone coordinate. First, we prepare two initial conditions in the hydrodynamic model for analyzing elliptic flow. Both initial conditions lead to reasonable agreement with single particle spectra in central and semicentral collisions. Second, by using these hydrodynamic simulations, we compare elliptic flow as a function of pseudorapidity with experimental data recently measured by the PHOBOS Collaboration. Our results are in agreement with experimental data only near midrapidity. This suggests that thermalization in the early stage of collisions is not achieved in forward and backward rapidity regions.