Dynamical pattern formation without self-attraction in quorum-sensing active matter: the interplay between nonreciprocity and motility

TL;DR

This study introduces a minimal quorum-sensing active matter model demonstrating that nonreciprocal interactions and motility can induce dynamic chasing band patterns without effective intra-species attraction, revealing new mechanisms of pattern formation.

Contribution

It uncovers a novel pattern formation mechanism driven by nonreciprocity and motility, independent of traditional attractive interactions, supported by simulations and linear stability analysis.

Findings

Chasing bands emerge from nonreciprocal interactions and motility.

System phase separates into chaotic bands and dilute gas with self-attraction.

Chaotic interface dynamics lead to slow coarsening of patterns.

Abstract

We study a minimal model involving two species of particles interacting via quorum-sensing rules. Combining simulations of the microscopic model and linear stability analysis of the associated coarse-grained field theory, we identify a mechanism for dynamical pattern formation that does not rely on the standard route of intra-species effective attractive interactions. Instead, our results reveal a highly dynamical phase of chasing bands induced only by the combined effects of self-propulsion and nonreciprocity in the inter-species couplings. Turning on self-attraction, we find that the system may phase separate into a macroscopic domain of such chaotic chasing bands coexisting with a dilute gas. We show that the chaotic dynamics of bands at the interfaces of this phase-separated phase results in anomalously slow coarsening.