Intermittent Attractive Interactions Lead to Microphase Separation in Non-motile Active Matter

TL;DR

This paper introduces a microscopic model of non-motile active matter with intermittent attractions, demonstrating microphase separation and the ability to tune cluster sizes, inspired by bacterial behavior.

Contribution

It presents a scalar active matter model with intermittent attractions that exhibits microphase separation and aligns with the Active Model B+ class, providing new insights into non-motile active systems.

Findings

Confirmation of microphase separation through numerical solutions

Switching rate controls cluster size in the model

Model aligns with the Active Model B+ class

Abstract

Non-motile active matter exhibits a wide range of non-equilibrium collective phenomena yet examples are crucially lacking in the literature. We present a microscopic model inspired by the bacteria {\it Neisseria Meningitidis} in which diffusive agents feel intermittent attractive forces. Through a formal coarse-graining procedure, we show that this truly scalar model of active matter exhibits the time-reversal-symmetry breaking terms defining the {\it Active Model B+} class. In particular, we confirm the presence of microphase separation by solving the kinetic equations numerically. We show that the switching rate controlling the interactions provides a regulation mechanism tuning the typical cluster size, e.g. in populations of bacteria interacting via type IV pili.