Extreme Superposition: Rogue Waves of Infinite Order and the Painlev\'e-III Hierarchy

TL;DR

This paper investigates the large-order limit of rogue wave solutions in the focusing nonlinear Schrödinger equation, revealing a new special function related to Painlevé-III hierarchy and providing detailed asymptotic analysis.

Contribution

The paper introduces the rogue wave of infinite order as a new special function and connects it to Painlevé-III hierarchy through a Riemann-Hilbert approach.

Findings

Existence of a limiting rogue wave profile as order tends to infinity.

Identification of the limiting profile with solutions of Painlevé-III hierarchy.

Asymptotic behavior matches numerical solutions and involves Painlevé-II in transitional regions.

Abstract

We study the fundamental rogue wave solutions of the focusing nonlinear Schr\"odinger equation in the limit of large order. Using a recently-proposed Riemann-Hilbert representation of the rogue wave solution of arbitrary order $k$, we establish the existence of a limiting profile of the rogue wave in the large-$k$ limit when the solution is viewed in appropriate rescaled variables capturing the near-field region where the solution has the largest amplitude. The limiting profile is a new particular solution of the focusing nonlinear Schr\"odinger equation in the rescaled variables --- the rogue wave of infinite order --- which also satisfies ordinary differential equations with respect to space and time. The spatial differential equations are identified with certain members of the Painlev\'e-III hierarchy. We compute the far-field asymptotic behavior of the near-field limit solution and compare the asymptotic formul\ae\ with the exact solution with the help of numerical methods for solving Riemann-Hilbert problems. In a certain transitional region for the asymptotics the near field limit function is described by a specific globally-defined tritronqu\'ee solution of the Painlev\'e-II equation. These properties lead us to regard the rogue wave of infinite order as a new special function.