Explicit harmonic and wave maps into variable-curvature surfaces

Fuente: arXiv
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Autori principali: Fotiadis, Anestis, Polychrou, Giannis
Natura: Preprint
Pubblicazione: 2025
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author Fotiadis, Anestis
Polychrou, Giannis
author_facet Fotiadis, Anestis
Polychrou, Giannis
contents Explicit harmonic and wave maps are typically available only in highly symmetric or constant-curvature settings, where additional symmetry or integrability structures are present. We develop a reduction framework for pseudo-Riemannian surfaces that extends explicit constructions to a geometrically significant class of variable-curvature targets. For target metrics of the form $A(R)\,dR^2 - δ^2 B(R)\,dS^2$, a geometrically adapted travelling-wave ansatz reduces the Euler--Lagrange system to a solvable system of first-order ODEs. The method applies simultaneously to harmonic and wave maps, treating the elliptic and hyperbolic regimes uniformly within a single framework. As concrete applications, we construct explicit harmonic maps into ellipsoids, Lorentzian wave maps into hyperboloids and the Schwarzschild exterior, and a mixed-signature example, all in genuinely variable-curvature geometries where explicit constructions are substantially less accessible.
format Preprint
id arxiv_https___arxiv_org_abs_2512_18376
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Explicit harmonic and wave maps into variable-curvature surfaces
Fotiadis, Anestis
Polychrou, Giannis
Differential Geometry
Analysis of PDEs
58E20, 53C43, 35L70, 53C50
Explicit harmonic and wave maps are typically available only in highly symmetric or constant-curvature settings, where additional symmetry or integrability structures are present. We develop a reduction framework for pseudo-Riemannian surfaces that extends explicit constructions to a geometrically significant class of variable-curvature targets. For target metrics of the form $A(R)\,dR^2 - δ^2 B(R)\,dS^2$, a geometrically adapted travelling-wave ansatz reduces the Euler--Lagrange system to a solvable system of first-order ODEs. The method applies simultaneously to harmonic and wave maps, treating the elliptic and hyperbolic regimes uniformly within a single framework. As concrete applications, we construct explicit harmonic maps into ellipsoids, Lorentzian wave maps into hyperboloids and the Schwarzschild exterior, and a mixed-signature example, all in genuinely variable-curvature geometries where explicit constructions are substantially less accessible.
title Explicit harmonic and wave maps into variable-curvature surfaces
topic Differential Geometry
Analysis of PDEs
58E20, 53C43, 35L70, 53C50
url https://arxiv.org/abs/2512.18376