Charged Dilatonic Spacetimes in String Theory

Abstract: We construct and study general static, spherically symmetric, magnetically charged solutions in Einstein-Maxwell-dilaton gravity in four dimensions. That is, taking Einstein gravity coupled to a ${\rm U}(1)$ gauge field and a massless dilaton$\unicode{x2014}$e.g., the action in the low-energy limit of string theory or Kaluza-Klein reduction$\unicode{x2014}$with arbitrary dilaton coupling, we build a three-parameter family of objects characterized by their mass, charge, and dilaton flux, generalizing the well known Garfinkle-Horowitz-Strominger black hole. We analyze the near-extremal and near-horizon behavior in detail, finding new warped geometries. In a particular limit, where the geometry reduces to the recently discovered customizable ${\rm AdS}_2 \times S^2$ of Einstein-Maxwell-dilaton gravity, we compute the static s-wave linearized solutions and characterize the anabasis relating the horizon perturbations to their nonlinear completions within our generalized family of spacetimes.