New Rotating Black Holes in String Theory

TL;DR

This work constructs rotating black hole solutions within a dilaton gravity model arising from low-energy string theory in three and four dimensions, revealing a fusion of Myers-Perry-like rotation without a Kerr-like extremality bound and Witten black hole–like thermodynamics with a mass-independent temperature. The authors exploit a large-$d$ limit of Myers-Perry black holes, together with a sphere reduction, to derive the D=3 and D=4 geometries that admit a linear dilaton vacuum and, in charged cases, closed timelike curves inside the inner horizon. They compute the full thermodynamics, including mass, angular momentum, entropy, temperature, charge, and potentials, and show a canonical ensemble with positive heat capacity, while the asymptotic symmetry group is enhanced to a more restrictive BMS$_2\times U(1)$ structure. A large-$d$ reduction on the action demonstrates how the same dilaton gravity model emerges from higher-dimensional Myers-Perry dynamics, offering a framework to generate new EFTs and non-trivial solutions. The results illuminate how large-$d$ methods complement near-horizon analyses and open avenues for connections to string dualities, holography, and black hole energy extraction scenarios such as the Penrose process.

Abstract

We present new black hole solutions to the low-energy effective action of string theory. We introduce three- and four-dimensional solutions that are rotating, asymptotically flat, and exhibit a linear dilaton vacuum. These solutions cannot be overspun, i.e., do not have an extremality condition, akin to higher-dimensional Myers-Perry black holes with one rotational angle. Studying their thermodynamics reveals that the temperature associated to these solutions does not depend on the black hole mass, similar to the Witten black hole. We also find that their asymptotic symmetry group is more stringent than the BMS group. We consider the charged generalisations for these black holes, which introduces closed timelike curves within the inner horizon. We show that these black holes can be derived from the large-$d$ limit of the Myers-Perry black hole. As such we advocate that large-$d$ can provide a useful vantage point to interpret the here introduced black holes, as well as more generally a way to generate new effective field theories and corresponding non-trivial solutions.