Holography and Irrelevant Operators

We explore the holographic proposal involving spacetimes with linear dilaton asymptotics in three dimensions from a gravity perspective. The holographic dual shares some properties with a symmetric product conformal field theory deformed by a single-trace analogue of the $T \overline{T}$ deformation. We present solutions of ten-dimensional supergravity which interpolate from BTZ black holes in the interior to either a linear dilaton spacetime near infinity, or to flat space. This allows a precise identification of field theory parameters with gravity parameters. The solutions manifestly exhibit the square root structure that is characteristic of $T \overline{T}$-deformed conformal field theories. We compute the mass of the spacetimes using the covariant phase space formalism and find agreement with the square root formula for the case of black holes without spin. We also discuss whether closed string tachyons might play a role when the deformation parameter becomes too large and the vacuum becomes unstable.