Instability mechanisms of repelling peak solutions in a multi-variable activator-inhibitor system

TL;DR

This paper investigates the stability of localized peak solutions in a multi-variable activator-inhibitor system, revealing instability in one dimension but potential stability in two dimensions influenced by domain and boundary conditions.

Contribution

It provides new insights into the stability and dynamics of multi-peak states in a complex biological model, highlighting behaviors absent in simpler two-variable systems.

Findings

All one-dimensional peak states are linearly unstable.

Two-dimensional states can be stable depending on domain and boundary conditions.

Front propagation influences the growth and destabilization of spots.

Abstract

We study the linear stability properties of spatially localized single- and multi-peak states generated in a subcritical Turing bifurcation in the Meinhardt model of branching. In one spatial dimension, these states are organized in a foliated snaking structure owing to peak-peak repulsion but are shown to be all linearly unstable, with the number of unstable modes increasing with the number of peaks present. Despite this, in two spatial dimensions direct numerical simulations reveal the presence of stable single- and multi-spot states whose properties depend on the repulsion from nearby spots as well as the shape of the domain and the boundary conditions imposed thereon. Front propagation is shown to trigger the growth of new spots while destabilizing others. The results indicate that multi-variable models may support new types of behavior that are absent from typical two-variable models.