Organizers of this minisymposium are

• Maxence Cassier (Marseille, France)
• Maryna Kachanovska (Paris, France)
• Konstantin Pankrashkin (Oldenburg, Germany)

This minisymposium aims at bringing together applied and pure mathematicians working on spectral theory and computations for waves propagating in non-standard media, where unusual effects occur due to the presence of interfaces, irregular or non-standard boundary conditions, or various degeneracies in the PDE coefficients. Physical applications are numerous, e.g. photonics (surface waves on the interface between metals and dielectrics), plasma physics (resonant behaviour of electromagnetic waves due to variations in ion density), fluid dynamics (attractor-like behaviour in vibrating fluids), black hole physics (instabilities of quasi-normal modes) and so on.
The above classes of problems often correspond to differential operators that are non-self-adjoint and/or non-elliptic, with potentially peculiar spectral properties, while a more detailed mathematical description of the above phenomena often relies on the analysis of viscosity-type limits of underlying problems, which mainly corresponds to the analysis of these operators near the spectrum. A special emphasis will thus be put on the precise spectral questions arising in applications as well as on the mathematically rigorous spectral analysis of less usual classes of operators.