Unruh radiation, holography, and boundary cosmology

A uniformly accelerated observer in anti–de Sitter spacetime is known to detect thermal radiation when the acceleration exceeds a critical value. We investigate the holographic interpretation of this phenomenon. For uniformly accelerated trajectories transverse to the boundary of the AdS space, the hologram is a blob that expands along the boundary. Observers on the boundary comoving with the hologram become observers in cosmological spacetimes. For supercritical accelerations one gets a Milne universe when the holographic screen is the boundary in Poincaré coordinates, while for the boundary in hyperspherical coordinates one gets de Sitter spacetimes. The presence or absence of thermality is then interpreted in terms of specific classes of observers in these cosmologies.