Splitting hairs of the three charge black hole
Iosif Bena
TL;DR
This work derives the large-radius limit of the metric for three-charge supertubes and BPS black rings by exploiting shared supersymmetry with constituent branes via Killing spinor methods. It shows that the near-tube geometries are smooth for regular tubes and develop horizons for black tubes, with the horizon area growing with the multiplicity of tube configurations, aligning with the black hole microstate program. The analysis uncovers a density-ratio constraint for tubes with two dipoles and identifies a critical parameter c_z that separates regular tubes from black rings in the large-radius limit, providing a concrete bridge between Born-Infeld results and supergravity. The results offer a framework to count microstates of three-charge tubes and test the proposal that black hole hair corresponds to a multitude of regular tube geometries, potentially proving aspects of Mathur’s conjecture.
Abstract
We construct the large radius limit of the metric of three charge supertubes and three charge BPS black rings by using the fact that supertubes preserve the same supersymmetries as their component branes. Our solutions reproduce a few of the properties of three charge supertubes found recently using the Born Infeld description. Moreover, we find that these solutions pass a number of rather nontrivial tests which they should pass if they are to describe some of the hair of three charge black holes and three charge black rings.
