Space-Time Cluster Analysis of an Aging Athermal System

We analyze the space-time structure of athermal aging. Specifically, we consider a 50:50 binary mixture of a purely repulsive harmonic binary system of size ratio 1:1.4 at packing fraction 0.9. We simulate the dynamics of the particles immersed in a solvent for the case of over-damped dynamics. Starting with random positions corresponding to a quench from infinite temperature, we observe the system as it approaches the final jammed state. We focus on rearrangement events by identifying particles whose velocity is large compared to the average velocity of their neighbors normalized by the average velocity of all particles. Particles undergoing rearrangement events form space-time clusters. We find that these space-time clusters are compact in space and time and that with increasing waiting time these clusters increase both in spatial size as well as in time duration following non-trivial power laws. The distribution of quiescent times between successive rearrangement events are waiting time independent and follow an initial power law with exponential tail.