Heterotic Black Horizons

TL;DR

This paper classifies supersymmetric near horizon geometries of heterotic black holes, revealing specific geometric structures and supersymmetry preservation conditions, including AdS_3 fibrations and special holonomy manifolds.

Contribution

It provides a detailed classification of heterotic black hole horizons based on supersymmetry and geometric structures, including new explicit solutions with extended supersymmetry.

Findings

Heterotic horizons are either AdS_3 fibrations with G_2 structures or R^{1,1} times Spin(7) manifolds.

Extended supersymmetry imposes additional geometric restrictions on the horizons.

Explicit solutions include AdS_3 * S^3 * T^4, AdS_3 * S^3 * K_3, and R^{1,1} * T^4 * K_3 with equal radii and constant dilaton.

Abstract

We show that the supersymmetric near horizon geometry of heterotic black holes is either an AdS_3 fibration over a 7-dimensional manifold which admits a G_2 structure compatible with a connection with skew-symmetric torsion, or it is a product R^{1,1} * S^8, where S^8 is a holonomy Spin(7) manifold, preserving 2 and 1 supersymmetries respectively. Moreover, we demonstrate that the AdS_3 class of heterotic horizons can preserve 4, 6 and 8 supersymmetries provided that the geometry of the base space is further restricted. Similarly R^{1,1} * S^8 horizons with extended supersymmetry are products of R^{1,1} with special holonomy manifolds. We have also found that the heterotic horizons with 8 supersymmetries are locally isometric to AdS_3 * S^3 * T^4, AdS_3 * S^3 * K_3 or R^{1,1} * T^4 * K_3, where the radii of AdS_3 and S^3 are equal and the dilaton is constant.