 | Average transverse and longitudinal pressures, $P_T= (T^{xx}+T^{yy})/2$ and $P_L=\tau^2 T^{\eta\eta}$, of a realistic heavy ion event evolved in succession by 2+1D Yang-Mills evolution (IP-glasma model)~\cite{Schenke:2012wb,Schenke:2012fw}, QCD kinetic theory (\kompost) and relativistic viscous hydrodynamics~\cite{Schenke:2010nt,Schenke:2010rr,Paquet:2015lta}. |
 | (a) Energy density and (b) velocity profiles in the hydrodynamic stage at time $\tau_\text{out}=2.0\,\text{fm}$, for different durations of the kinetic preequilibrium stage ($\tauekt \rightarrow \tauhydro$). |
 | Evolution of the background energy density in kinetic theory for two values of the coupling constant $\lambda$, corresponding to a range of specific shear viscosities $\eta/s\approx 0.16{-}0.62$. Scaling the vertical axis by the ideal hydrodynamic asymptotics $e_\text{id.}=\nu_g \pi^2\TId^4/30$ and the horizontal axis by the kinetic relaxation time $\tau_\text{R}(\tau) \equiv (\eta/s)/\TId(\tau)$ reveals that the nonequilibrium evolution follows a universal attractor curve which smoothly interpolates between free streaming at early times and viscous hydrodynamics at late times. |
 | Evolution of the transverse energy density profile calculated within the linear response framework \kompost{}, from early time $\tauekt\sim 0.1\,\text{fm/c}$ to hydrodynamization time $\tauhydro\sim 1.0\,\text{fm/c}$. The energy-momentum tensor at each point $\x$ in the transverse plane receives causal contributions from the local average background, and linearized energy and momentum perturbations propagated from $\tauekt$ to $\tauhydro$ (\Eq{eq:pert_evol}). The causal past for point $\x$ is indicated by the black cone and white circle. |