Dynamical black holes in low-energy string theory

Abstract

We investigate time-dependent spherically symmetric solutions of the four-dimensional Einstein-Maxwell-axion-dilaton system, with the dilaton coupling that occurs in low-energy effective heterotic string theory. A class of dilaton-electrovacuum radiating solutions with a trivial axion, previously found by Güven and Yörük, is re-derived in a simpler manner and its causal structure is clarified. It is shown that such dynamical spacetimes featuring apparent horizons do not possess a regular light-like past null infinity or future null infinity, depending on whether they are radiating or accreting. These solutions are then extended in two ways. First we consider a Vaidya-like generalisation, which introduces a null dust source. Such spacetimes are used to test the status of cosmic censorship in the context of low-energy string theory. We prove that - within this family of solutions - regular black holes cannot evolve into naked singularities by accreting null dust, unless standard energy conditions are violated. Secondly, we employ S-duality to derive new time-dependent dyon solutions with a nontrivial axion turned on. Although they share the same causal structure as their Einstein-Maxwell-dilaton counterparts, these solutions possess both electric and magnetic charges.

1+24 pages + appendices, 6 figures; v2: minor corrections, added reference, matches published version

References in corpus (4)

• Exact Black Hole Formation in Asymptotically (A)dS and Flat Spacetimes
• (Super-)renormalizably dressed black holes
• Exact Collapse Solutions in D=4, N=4 Gauged Supergravity and Their Generalizations
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Cited by in corpus (6)

• Vaidya Spacetime in Massive Gravity's Rainbow
• Static charged dilaton black hole cannot be overcharged by gedanken experiments
• Scalar charge of black holes in Einstein-Maxwell-dilaton theory
• Self-similarity in Einstein-Maxwell-dilaton theories and critical collapse
• Charged Particle Production Rate from Cosmic Censorship in Dilaton Black Hole Spacetimes
• Self-similar solutions and critical behavior in Einstein-Maxwell-dilaton theory sourced by charged null fluids