What can we learn from hydrodynamic analysis of elliptic flow?

We can establish a new picture, the perfect fluid strongly coupled quark gluon plasma (sQGP) core and the dissipative hadronic corona, of the space-time evolution of produced matter in relativistic heavy ion collisions at RHIC. It is also shown that the picture works well also in the forward rapidity region through an analysis based on a new class of the hydro-kinetic model and is a manifestation of deconfinement.