Pulled fronts are not (just) pulled

Fuente: arXiv
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Main Authors: Avery, Montie, Holzer, Matt, Scheel, Arnd
Format: Preprint
Published: 2025
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author Avery, Montie
Holzer, Matt
Scheel, Arnd
author_facet Avery, Montie
Holzer, Matt
Scheel, Arnd
contents Front propagation into unstable states is often determined by the linearization, that is, propagation speeds agree with predictions from the linearized equation at the unstable state. The leading edge behavior is then a Gaussian tail propagating with the linear spreading speed. Fronts following this leading edge are commonly referred to as pulled fronts, alluding to the idea that they are ``pulled'' by this leading-edge Gaussian tail. We describe here a class of examples that exhibits how these leading-order effects do not completely describe the dynamics in the wake of the front. In fact, leading edge behavior predicts at most two possible invasion scenarios, associated with positive and negative amplitudes of the Gaussian tail, but our examples exhibit three or more invasion fronts with different states in the wake. The resulting invasion process therefore leaves behind a state that is not solely determined by the leading edge, and thus not just pulled by the Gaussian tail.
format Preprint
id arxiv_https___arxiv_org_abs_2508_14864
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Pulled fronts are not (just) pulled
Avery, Montie
Holzer, Matt
Scheel, Arnd
Analysis of PDEs
Pattern Formation and Solitons
Front propagation into unstable states is often determined by the linearization, that is, propagation speeds agree with predictions from the linearized equation at the unstable state. The leading edge behavior is then a Gaussian tail propagating with the linear spreading speed. Fronts following this leading edge are commonly referred to as pulled fronts, alluding to the idea that they are ``pulled'' by this leading-edge Gaussian tail. We describe here a class of examples that exhibits how these leading-order effects do not completely describe the dynamics in the wake of the front. In fact, leading edge behavior predicts at most two possible invasion scenarios, associated with positive and negative amplitudes of the Gaussian tail, but our examples exhibit three or more invasion fronts with different states in the wake. The resulting invasion process therefore leaves behind a state that is not solely determined by the leading edge, and thus not just pulled by the Gaussian tail.
title Pulled fronts are not (just) pulled
topic Analysis of PDEs
Pattern Formation and Solitons
url https://arxiv.org/abs/2508.14864