Homoclinic bifurcations at the onset of pulse self-replication

Abstract

We establish a series of properties of symmetric, N-pulse, homoclinic solutions of the reduced Gray–Scott system: u ″ = u v 2 , v ″ = v − u v 2 , which play a pivotal role in questions concerning the existence and self-replication of pulse solutions of the full Gray–Scott model. Specifically, we establish the existence, and study properties, of solution branches in the ( α , β ) -plane that represent multi-pulse homoclinic orbits, where α and β are the central values of u ( x ) and v ( x ) , respectively. We prove bounds for these solution branches, study their behavior as α → ∞ , and establish a series of geometric properties of these branches which are valid throughout the ( α , β ) -plane. We also establish qualitative properties of multi-pulse solutions and study how they bifurcate, i.e., how they change along the solution branches.