Spatially Structured Flocking in a Proliferating Population of Self-Propelled Organisms without Explicit Alignment Interactions

TL;DR

This paper introduces the active Brownian bug (ABB) model demonstrating that self-replication and death can induce flocking behavior in self-propelled particles without explicit alignment, revealing a new flocking mechanism.

Contribution

The study presents a novel model showing flocking emerges from stochastic birth and death processes, independent of alignment interactions, in proliferating cellular populations.

Findings

Flocking occurs without explicit alignment interactions.

Ordered hexagonal arrays are maintained during flocking.

Stochastic birth and death processes drive emergent order.

Abstract

While it is well established that self-propelled particles with alignment interactions can exhibit orientational order, the impact of self-replication and annihilation, which are key characteristics in cellular systems, on spatiotemporal order remains poorly understood. To explore the interplay between self-propulsion and self-replication, we introduce the active Brownian bug (ABB) model, in which self-propelled agents undergo stochastic, density-dependent replication and constant-rate death. Despite the absence of alignment interactions, the system exhibits flocking behavior characterized by high orientational order, while maintaining ordered hexagonal arrays. This emergent order arises from stochastic birth and death processes, offering a novel mechanism for flocking in proliferating cellular populations.