Spherically Collapsing Matter in AdS, Holography, and Shellons

TL;DR

The paper addresses holographic diagnostics of gravitational collapse by analyzing a slowly collapsing spherical shell in AdS and its imprint on boundary correlators. It develops a bulk-to-boundary computation for a scalar field in shell backgrounds, using interior–exterior matching to obtain the retarded propagator in the boundary theory. A key finding is a tower of unstable resonances, the shellons, whose masses scale with the shell radius and whose finite lifetimes reflect the non-equilibrium nature of the setup. The work provides a concrete mechanism by which bulk shell geometry leaves observable signatures in the boundary, advancing the holographic understanding of black hole formation and thermalization.

Abstract

We investigate the collapse of a spherical shell of matter in an anti-de Sitter space. We search for a holographic description of the collapsing shell in the boundary theory. It turns out that in the boundary theory it is possible to find information about the radial size of the shell. The shell deforms the background spacetime, and the deformed background metric enters into the action of a generic bulk field. As a consequence, the correlators of operators coupling to the bulk field are modified. By studying the analytic structure of the correlators, we find that in the boundary theory there are unstable excitations ("shellons") whose masses are multiples of a scale set by the radius of the shell. We also comment on the relation between black hole formation in the bulk and thermalization in the boundary.