Momentum-carrying waves on D1-D5 microstate geometries

Understand

If one attempts to add momentum-carrying waves to a black string then the solution develops a singularity at the horizon; this is a manifestation of the 'no hair theorem' for black objects.

• However individual microstates of a black string do not have a horizon, and so the above theorem does not apply.
• We construct a perturbation that adds momentum to a family of microstates of the extremal D1-D5 string.
• This perturbation is analogous to the 'singleton' mode localized at the boundary of AdS; to leading order it is pure gauge in the AdS interior of the geometry.