Phase segregation of passive advective particles in an active medium

TL;DR

This paper investigates how passive particles get segregated in an active medium with dynamic asters, revealing unique nonequilibrium behaviors like diffuse interfaces and multiscaling fluctuations, relevant to cellular actin dynamics.

Contribution

It introduces a model for phase segregation of passive scalars in a medium of active asters, highlighting novel coarsening dynamics and fluctuation phenomena in nonequilibrium conditions.

Findings

Strong violation of Porod behaviour indicating diffuse interfaces

Presence of multiscaling and intermittency in fluctuations

Dependence of phase segregation on aster density and remodeling rates

Abstract

Localized contractile configurations or asters spontaneously appear and disappear as emergent structures in the collective stochastic dynamics of active polar actomyosin filaments. Passive parti- cles which (un)bind to the active filaments get advected into the asters, forming transient clusters. We study the phase segregation of such passive advective scalars in a medium of dynamic asters, as a function of the aster density and the ratio of the rates of aster remodeling to particle diffusion. The dynamics of coarsening shows strong violation of Porod behaviour, suggesting diffuse interfaces. The phase segregated steady state shows strongly fluctuations characterized by multiscaling and in- termittency. We expect these unique nonequilibrium features to manifest in the actin-dependent molecular clustering at the cell surface.