Matrix models from black hole geometries

Supersymmetric, magnetically charged (and possibly accelerating) black holes in AdS$_4$ that uplift on Sasaki-Einstein manifolds $Y_7$ to M-theory have a dual matrix model description. The matrix model in turn arises by localization of the 3d $\mathcal{N}=2$ SCFTs, dual to the AdS$_4$ vacuum, on the black hole horizon geometry, which is a Riemann surface $\Sigma_g$ (or a spindle $\Sigma$). We identify the imaginary part $t$ of the continuously distributed eigenvalues in the matrix model, and their density function $\rho(t)$, with natural geometric quantities associated with the M-theory circle action $U(1)_M$ on the near-horizon geometry AdS$_2\times Y_9$, the internal space $Y_9$ being a $Y_7$ fibration over $\Sigma_g$ (or $\Sigma$). Moreover, we argue that the points where $\rho'(t)$ is discontinuous match with the classical action of BPS probe M2-branes wrapping AdS$_2$ and the M-theory circle. We illustrate our findings with the ABJM and ADHM theories, whose duals have $Y_7 = S^7/\mathbb{Z}_k$, and some of their flavoured variants corresponding to other toric $Y_7$.