A Morse-Bott unification of the Grassmannians of a symplectic vector space

We construct a quadratic Morse-Bott function on the real Grassmannian of a symplectic vector space from a compatible linear complex structure. We show that its critical loci consist of linear subspaces that split into isotropic and complex parts and that its stable manifolds coincide with the orbits of the linear symplectomorphism group. These orbits generalize the Lagrangian, symplectic, isotropic, and coisotropic Grassmannians to include the Grassmannians of linear subspaces that are neither isotropic, coisotropic, nor symplectic. The negative gradient flow deformation retracts these spaces onto compact homogeneous spaces for the unitary group.

💡 Research Summary

The paper introduces a quadratic Morse‑Bott function on the real Grassmannian of a symplectic vector space (V, ω) equipped with a compatible linear complex structure J. For a k‑dimensional subspace W⊂V, the authors define the energy  f(W)=½ Tr(