The slowly rotating near extremal D1-D5 system as a `hot tube'

TL;DR

The paper investigates the slowly rotating near-extremal D1-D5 system and shows that a small angular momentum truncates the geometry’s throat into a long, reflecting tube. By solving the massless scalar wave equation via two-region asymptotic matching, it demonstrates that incident quanta largely reflect at the throat end, dwell for times set by the throat length, and can form a hot, thermal-like tube whose emission mimics near-extremal black-hole radiation. A key result is the identification of the length scale $Rn_1n_5$, equal to the effective-string length, which governs the endpoint behavior, the onset of nonlinearity, and the thermodynamics of the hot tube. The authors then discuss how different D1-D5 CFT states (including branching into multiple strands) could modify throat structure, suggesting a holographic picture in which information might be carried by throat dynamics and branching, with implications for the black-hole information problem.

Abstract

The geometry of the D1-D5 system with a small angular momentum j has a long throat ending in a conical defect. We solve the scalar wave equation for low energy quanta in this geometry. The quantum is found to reflect off the end of the throat, and stay trapped in the throat for a long time. The length of the throat for j=1/2 equals n_1n_5 R, the length of the effective string in the CFT; we also find that at this distance the incident wave becomes nonlinear. Filling the throat with several quanta gives a `hot tube' which has emission properties similar to those of the near extremal black hole.