Hitchin systems are algebraically completely integrable systems foliating a dense subset of Higgs bundle moduli spaces by abelian torsors. This structure played a crucial role in recent developments in the field, e. g. Langlands duality and the GMN-conjecture. In this talk, we take a closer look at degenerate fibres of the symplectic and odd orthogonal Hitchin system. We give a new approach identifying a certain class of these fibres with SL(2,C)-Hitchin fibres of twisted Higgs bundles. This allows to study these degenerated Hitchin fibres by semi-abelian spectral data - a generalisation of the abelianisation procedure for regular Hitchin fibres introducing Hecke modifications at the singularities of the spectral curve.
4:30 pm (WET / GMT)