Stable blowup for supercritical wave maps into perturbed spheres
Roland Donninger, Birgit Schörkhuber, Alexander Wittenstein
TL;DR
This work addresses stable self-similar blowup for energy-supercritical wave maps from $(1+d)$-dimensional Minkowski space into perturbed spheres $S^d_{\epsilon}$ under co-rotational symmetry. The authors reformulate the problem in similarity coordinates, construct self-similar blowup profiles by a perturbative fixed-point argument around the ground state at $\epsilon=0$, and prove nonlinear stability of these blowup solutions under small co-rotational perturbations on the full space via spectral analysis and a robust contraction mapping in an abstract Cauchy problem. The analysis relies on intersection Sobolev spaces, Schauder-type estimates with parameter dependence, and a careful treatment of the symmetry-induced unstable mode to ensure exponential decay on the stable subspace. The results extend prior stability results known for the sphere target to a class of warped-product targets close to the sphere, deepening understanding of blowup dynamics in geometric wave equations and suggesting broader robustness of self-similar blowup phenomena under scale-invariant perturbations.
Abstract
We consider wave maps from $(1+d)$-dimensional Minkowski space, $d\geq3$, into rotationally symmetric manifolds which arise from small perturbations of the sphere $\mathbb S^d$. We prove the existence of co-rotational self-similar finite time blowup solutions with smooth blowup profiles. Furthermore, we show the nonlinear asymptotic stability of these solutions under suitably small co-rotational perturbations on the full space.
