Azimuthal anisotropy: Transition from hydrodynamic flow to jet suppression

Measured second and fourth azimuthal anisotropy coefficients v{sub 2,4}(N{sub part},p{sub T}) are scaled with the initial eccentricity {var_epsilon}{sub 2,4}(N{sub part}) of the collision zone and studied as a function of the number of participants N{sub part} and the transverse momenta p{sub T}. Scaling violations are observed for p{sub T} {le} 3 GeV/c, consistent with a p{sub T}{sup 2} dependence of viscous corrections and a linear increase of the relaxation time with p{sub T}. These empirical viscous corrections to flow and the thermal distribution function at freeze-out constrain estimates of the specific viscosity and the freeze-out temperature for two different models for the initial collision geometry. The apparent viscous corrections exhibit a sharp maximum for p{sub T} {ge} 3 GeV/c, suggesting a breakdown of the hydrodynamic ansatz and the onset of a change from flow-driven to suppression-driven anisotropy.