S-Duality at the Black Hole Threshold in Gravitational Collapse

TL;DR

This paper investigates the critical behavior in gravitational collapse of axion/dilaton fields, revealing a new self-similar solution exhibiting S-duality and universal scaling near black hole formation threshold.

Contribution

It introduces a novel spherically symmetric, continuously self-similar solution for axion/dilaton collapse, demonstrating S-duality in the echoing behavior and extending critical collapse understanding.

Findings

Discovery of a new critical solution with self-similarity

Observation of S-duality in echoing behavior

Collapse results in outgoing axion/dilaton radiation

Abstract

We study gravitational collapse of the axion/dilaton field in classical low energy string theory, at the threshold for black hole formation. A new critical solution is derived that is spherically symmetric and continuously self-similar. The universal scaling and echoing behavior discovered by Choptuik in gravitational collapse appear in a somewhat different form. In particular, echoing takes the form of SL(2,R) rotations (cf. S-duality). The collapse leaves behind an outgoing pulse of axion/dilaton radiation, with nearly but not exactly flat spacetime within it.