Published online by Cambridge University Press: 14 December 2021
We study the action of a real reductive group G on a real submanifold X of a Kähler manifold Z. We suppose that the action of a compact connected Lie group U with Lie algebra $\mathfrak {u}$ extends holomorphically to an action of the complexified group
$U^{\mathbb {C}}$ and that the U-action on Z is Hamiltonian. If
$G\subset U^{\mathbb {C}}$ is compatible, there exists a gradient map
$\mu _{\mathfrak p}:X \longrightarrow \mathfrak p$ where
$\mathfrak g=\mathfrak k \oplus \mathfrak p$ is a Cartan decomposition of
$\mathfrak g$. In this paper, we describe compact orbits of parabolic subgroups of G in terms of the gradient map
$\mu _{\mathfrak p}$.
Biliotti was partially supported by the Project PRIN 2015, Real and Complex Manifolds: Geometry, Topology and Harmonic Analysis, by the Project PRIN 2017, Real and Complex Manifolds: Topology, Geometry and Holomorphic Dynamics, and by the GNSAGA INdAM.