Rigidity of quasi-Einstein metrics: The incompressible case

Author:

Eric Bahuaud, Sharmila Gunasekaran, Hari K Kunduri, Eric Woolgar

Keyword:

Mathematics, Differential Geometry, Differential Geometry (math.DG), General Relativity and Quantum Cosmology (gr-qc)

journal:

date:

2023-07-02 16:00:00

Abstract

As part of a programme to classify quasi-Einstein metrics $(M,g,X)$ on closed manifolds and near-horizon geometries of extreme black holes, we study such spaces when the vector field $X$ is divergence-free but not identically zero. This condition is satisfied by left-invariant quasi-Einstein metrics on compact homogeneous spaces (including the near-horizon geometry of an extreme Myers-Perry black hole with equal angular momenta in two distinct planes), and on certain bundles over K\"ahler-Einstein manifolds. We find that these spaces exhibit a mild form of rigidity: they always admit a one-parameter group of isometries generated by $X$. Further geometrical and topological restrictions are also obtained.

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