Growing length and time scales in activity-mediated glassy dynamics in confluent cell monolayers

TL;DR

This study investigates how activity, via self-propulsion, influences glassy dynamics in confluent cell monolayers, revealing that active fluctuations extend length and time scales, with structure-dynamics feedback controlling relaxation.

Contribution

It introduces the first computation of a dynamic length scale in confluent systems and demonstrates the impact of activity on glassy dynamics through simulations and mode-coupling theory.

Findings

Relaxation time scales with dynamic length scale as a power law.

Static length scale is proportional to the dynamic length scale.

Active fluctuations do not alter the nature of the glass transition.

Abstract

Activity-mediated unjamming of a confluent glassy system is crucial for several biological processes, such as embryogenesis and cancer metastasis. During these processes, the cells progressively change their junction properties, characterized by an interaction parameter $p_0$, and become motile. Here, we study the effect of nonequilibrium active fluctuations, in the form of self-propulsion, on the glassy dynamics in a confluent system. We simulate the active Vertex model and use the analytical mode-coupling theory (MCT) to show that the nature of the transition in the presence of activity remains similar to that in a thermal system where the fluctuations are temperature-like. The agreement of the simulation results with the MCT predictions demonstrates that the structure-dynamics feedback mechanism controls the relaxation dynamics. In addition, we present the first computation of a dynamic length scale, $\xi_d$, in confluent systems using finite-size scaling, and show that the growing relaxation time exhibita a power-law dependence on $\xi_d$. Furthermore, unlike particulate glasses, the static length that governs the finite-size scaling of the relaxation time is proportional to $\xi_d$, revealing the unique nature of the glassy dynamics in confluent systems.