AdS gravastar and bulk-cone singularities

TL;DR

This paper demonstrates how the AdS/CFT correspondence can be used to probe the interior region of a gravastar geometry, specifically inside the photon sphere, by analyzing bulk-cone singularities in the dual conformal field theory.

Contribution

It introduces a method to investigate the interior of gravastar geometries using bulk-cone singularities in the dual CFT, extending the understanding of holographic probes beyond black hole horizons.

Findings

Bulk-cone singularities encode null geodesics into the interior region.

Numerical computation of retarded Green functions reveals signatures of the interior geometry.

The approach allows examination of regions inside the photon sphere via dual CFT analysis.

Abstract

The horizon of black hole is surrounded by the photon sphere and an outside observer cannot easily examine the geometry inside the photon sphere. In this note, we propose a way to investigate the region from dual conformal field theory by making use of AdS/CFT correspondence. We first construct gravastar geometry as an asymptotic anti-de Sitter spacetime, where the region inside the photon sphere is replaced by a horizon-less geometry. It is known that bulk-cone singularities in the retarded Green function in dual conformal field theory can encode the bulk null geodesics. We then compute numerically the retarded Green function from the bulk theory and observe bulk-cone singularities corresponding to null geodesics traveling into the interior region. In this way, we show that it is possible to examine the region inside the photon sphere from bulk-cone singularities of dual conformal field theory.