Kerr Isolated Horizons in Ashtekar and Ashtekar-Barbero Connection Variables

Christian Röken (1)

1 CPT - Centre de Physique Théorique - UMR 7332

The Ashtekar and Ashtekar–Barbero connection variable formulations of Kerr isolated horizons are derived. Using a regular Kinnersley tetrad in horizon-penetrating Kruskal–Szekeres-like coordinates, the spin coefficients of Kerr geometry are determined by solving the first Maurer–Cartan equation of structure. Isolated horizon conditions are imposed on the tetrad and the spin coefficients. A transformation into an orthonormal tetrad frame that is fixed in the time gauge is applied and explicit calculations of the spin connection, the Ashtekar and Ashtekar–Barbero connections, and the corresponding curvatures on the horizon 2-spheres are performed. Since the resulting Ashtekar–Barbero curvature does not comply with the simple form of the horizon boundary condition of Schwarzschild isolated horizons, i.e., on the horizon 2-spheres, the Ashtekar–Barbero curvature is not proportional to the Plebanski 2-form, which is required for an SU(2) Chern–Simons treatment of the gauge degrees of freedom in the horizon boundary in the context of loop quantum gravity, a general method to construct a new connection whose curvature satisfies such a relation for Kerr isolated horizons is introduced. For the purpose of illustration, this method is employed in the framework of slowly rotating Kerr isolated horizons.

Mots clés: Kerr isolated horizons; Ashtekar–Barbero connection variables; Horizon boundary condition; horizon: geometry; quantum gravity: loop space; black hole: quantum; symmetry: axial; space-time: Kerr; boundary condition; semiclassical; self-duality

Domaines: Relativité Générale et Cosmologie Quantique [gr-qc]

Christian Röken. Kerr Isolated Horizons in Ashtekar and Ashtekar-Barbero Connection Variables. Gen.Rel.Grav., 2017, 49 (9), pp.114. ⟨10.1007/s10714-017-2251-6⟩. ⟨hal-01582859⟩