title: Front interaction induces excitable behavior.
abstract: Spatially extended systems can support local transient excitations in which just a part of the system is excited. The mechanisms reported so far are local excitability and excitation of a localized structure. Here we introduce an alternative mechanism based on the coexistence of two homogeneous stable states and spatial coupling. We show the existence of a threshold for perturbations of the homogeneous state. Subthreshold perturbations decay exponentially. Superthreshold perturbations induce the emergence of a long-lived structure formed by two back to back fronts that join the two homogeneous states. While in typical excitability the trajectory follows the remnants of a limit cycle, here reinjection is provided by front interaction, such that fronts slowly approach each other until eventually annihilating. This front-mediated mechanism shows that extended systems with no oscillatory regimes can display excitability.
authors.affiliation: Instituto de Física Interdisciplinar y Sistemas Complejos, IFISC (CSIC-UIB), Campus Universitat de les Illes Balears, E-07122 Palma de Mallorca, Spain.|Applied Physics Research Group, APHY, Vrije Universiteit Brussel, 1050 Brussels, Belgium.
authors.forename: P
authors.initials: P
authors.lastname: Parra-Rivas
authors.affiliation: Instituto de Física Interdisciplinar y Sistemas Complejos, IFISC (CSIC-UIB), Campus Universitat de les Illes Balears, E-07122 Palma de Mallorca, Spain.
authors.forename: M A
authors.initials: MA
authors.lastname: Matías
authors.affiliation: Instituto de Física Interdisciplinar y Sistemas Complejos, IFISC (CSIC-UIB), Campus Universitat de les Illes Balears, E-07122 Palma de Mallorca, Spain.
authors.forename: P
authors.initials: P
authors.lastname: Colet
authors.affiliation: Applied Physics Research Group, APHY, Vrije Universiteit Brussel, 1050 Brussels, Belgium.|Laboratory of Dynamics in Biological Systems, Department of Cellular and Molecular Medicine, University of Leuven (KU Leuven), B-3000 Leuven, Belgium.
authors.forename: L
authors.initials: L
authors.lastname: Gelens
authors.affiliation: Instituto de Física Interdisciplinar y Sistemas Complejos, IFISC (CSIC-UIB), Campus Universitat de les Illes Balears, E-07122 Palma de Mallorca, Spain.
authors.forename: D
authors.initials: D
authors.lastname: Walgraef
authors.affiliation: Instituto de Física Interdisciplinar y Sistemas Complejos, IFISC (CSIC-UIB), Campus Universitat de les Illes Balears, E-07122 Palma de Mallorca, Spain.
authors.forename: D
authors.initials: D
authors.lastname: Gomila