11 citations · 12 across the 6 of their papers we have counts for
7 papers
Propagation of Polarization in Transmission Problems
Sönke Hansen
For geometric systems of real principal type, we define a subprincipal symbol and derive a transport equation for polarizations which, in the scalar case, is a well-known equation…
Boundary Values of Eigenfunctions on Riemannian Symmetric Spaces
Sönke Hansen, Joachim Hilgert, Aprameyan Parthasarathy
We give a new and self-contained proof of a generic version of the (former) Helgason conjecture. It says that for generic spectral parameters the Poisson transform is a topological…
Resonances and Scattering Poles in Symmetric Spaces of Rank One
Sönke Hansen, Joachim Hilgert, Aprameyan Parthasarathy
We relate resolvent and scattering kernels for the Laplace operator on Riemannian symmetric spaces of rank one via boundary values in the sense of Kashiwara-Oshima. From this, we d…
Subsonic Free Surface Waves in Linear Elasticity
Sönke Hansen
For general anisotropic linear elastic solids with smooth boundaries, Rayleigh-type surface waves are studied. Using spectral factorizations of matrix polynomials, a self-contained…
Patterson--Sullivan distributions in higher rank
Sönke Hansen, Joachim Hilgert, Michael Schröder
For a compact locally symmetric space $\XG$ of non-positive curvature, we consider sequences of normalized joint eigenfunctions which belong to the principal spectrum of the algebr…
Rayleigh-type Surface Quasimodes in General Linear Elasticity
Sönke Hansen
Rayleigh-type surface waves correspond to the characteristic variety, in the elliptic boundary region, of the displacement-to-traction map. In this paper, surface quasimodes are co…