Analytic Metric for Rotating Black Holes in Higher-Derivative Gravity

Abstract

We turn metric reconstruction into an analytic solver for rotating black holes in modified gravity, bypassing the direct solution of coupled field equations. As an example, in parity-even cubic gravity, we construct the first analytic spinning black hole metric at linear order in the coupling, without spin or weak-field expansions. We stringently validate the field equations and reproduce independent analytic predictions for horizon properties. This establishes a new route to construct spinning black holes beyond Einstein gravity and lays the foundation for strong-field tests.

8 pages, 3 figures for the main text; and 14 pages, 1 figure for the End Matter and Supplemental Material