Effective Microstructure

TL;DR

This paper introduces simplified effective descriptions of complex microstate geometries in AdS$_3$/CFT$_2$, capturing key features of both supergravity and stringy solutions through three-center models, revealing insights into microstructure and momentum distribution.

Contribution

It demonstrates that complex microstate solutions can be effectively described by simpler three-center configurations, bridging supergravity and string theory descriptions.

Findings

Effective descriptions capture key features of microstates.

Three-center solutions model superstrata and worldsheet solutions.

Momentum migration is elucidated in effective models.

Abstract

In AdS$_3$/CFT$_2$ duality, there are large families of smooth, horizonless microstate geometries that correspond to heavy pure states of the dual CFT. The metric and fluxes are complicated functions of up to five coordinates. There are also many duals of heavy pure states that cannot be described in supergravity, but only admit a worldsheet description. Extracting the physical properties of these solutions is technically challenging. In this paper, we show that there are much simpler effective descriptions of these solutions that capture many of their stringy and geometrical features, at the price of sacrificing supergravity smoothness. In particular, the effective description of some families of superstrata, and of certain worldsheet solutions, is given by easy-to-construct three-center solutions. For example, the effective description of a superstratum with a long AdS$_2$ throat is a scaling, three-center solution in which the momentum wave is collapsed to a singular source at one of the three centers. This also highlights how momentum migrates away from the supertube locus in the back-reacted geometry. Our results suggest that effective descriptions can be extended to more general microstates, and that many singular multi-center solutions can in fact correspond to effective descriptions of smooth horizonless microstructure.