Holography and colliding gravitational shock waves in asymptotically AdS_5 spacetime

TL;DR

The paper investigates the real-time thermalization of a strongly coupled four-dimensional conformal plasma by simulating the gravitational dual of colliding planar shocks in $AdS_5$ spacetime. It develops a robust numerical scheme using a nested linear structure and horizon excision in generalized EF coordinates to evolve the bulk geometry and extract the holographic stress-energy tensor $T^{\mu\nu}$. The results show rapid energy deposition after collision and a gradual approach to hydrodynamics, with first-order viscous hydrodynamics becoming accurate after a few inverse temperatures and notable second-order effects near the forward front, illustrating far-from-equilibrium dynamics bridging to near-equilibrium behavior. This work provides a quantitative link between early-time far-from-equilibrium evolution and late-time hydrodynamic flow in strongly coupled gauge theories, with implications for modeling the quark-gluon plasma.

Abstract

Using holography, we study the collision of planar shock waves in strongly coupled N=4 supersymmetric Yang-Mills theory. This requires the numerical solution of a dual gravitational initial value problem in asymptotically anti-de Sitter spacetime.

Figures (3)

• Figure 1: Energy density $\mathcal{E}/ \mu^4$ as a function of time $v$ and longitudinal coordinate $z$.
• Figure 2: Energy flux $\mathcal{S}/ \mu^4$ as a function of time $v$ and longitudinal coordinate $z$.
• Figure 3: Longitudinal and transverse pressure as a function of time $v$, at $z=0$ and $z = 3/\mu$. Also shown for comparison are the pressures predicted by the viscous hydrodynamic constitutive relations.