Electrovacuum near-horizon geometries in four and five dimensions

Associated with every stationary extremal black hole is a unique near-horizon geometry, itself a solution of the field equations. These latter spacetimes are more tractable to analyze and most importantly, retain properties of the original black hole which are intrinsic to the event horizon. After reviewing general features of near-horizon geometries, such as SO(2, 1) symmetry enhancement, I report on recent work on stationary, charged extremal …