Unpeeling a homoclinic banana in the fitzhugh–nagumo system

Paul Carter, Björn Sandstede

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


The FitzHugh–Nagumo equations are known to admit fast traveling pulse solutions with monotone tails. It is also known that this system admits traveling pulses with exponentially decaying oscillatory tails. Upon numerical continuation in parameter space, it has been observed that the oscillations in the tails of the pulses grow into a secondary excursion resembling a second copy of the primary pulse. In this paper, we outline in detail the geometric mechanism responsible for this single-to-double-pulse transition, and we construct the transition analytically using geometric singular perturbation theory and blow-up techniques.

Original languageEnglish (US)
Pages (from-to)236-349
Number of pages114
JournalSIAM Journal on Applied Dynamical Systems
Issue number1
StatePublished - 2018
Externally publishedYes

Bibliographical note

Funding Information:
∗Received by the editors June 20, 2016; accepted for publication (in revised form) December 1, 2017; published electronically January 30, 2018. http://www.siam.org/journals/siads/17-1/M108070.html Funding: The work of the first author was supported by the NSF under grant DMS-1148284. The work of the second author was partially supported by the NSF through grant DMS-1408742. †Department of Mathematics, University of Arizona, Tucson, AZ 85721 (pacarter@math.arizona.edu). ‡Division of Applied Mathematics, Brown University, Providence, RI 02912 (Bjorn Sandstede@brown.edu).


  • Blow-up
  • Canards
  • FitzHugh–Nagumo
  • Geometric singular perturbation theory
  • Traveling waves

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