Thermal bath in de Sitter space from holography

We consider the AdS/dS CFT correspondence and use holography to study the thermal nature of field theory in de Sitter space. Unlike the temperature of a thermal field theory in flat spacetime, the temperature of a superconformal field theory on de Sitter space is an integral part of the theory and leaves intact the conformal symmetry and supersymmetry. In the dual AdS side with the de Sitter factor written in planar coordinates, there is neither a black hole nor a cosmological horizon like that in static coordinates. Instead we have cosmological expansion of the de Sitter space. We consider a number of different observables, such as the entanglement entropy and Wilson loops corresponding to static and spinning mesons in the field theory, and study their thermal properties using holography. We show clearly how the field theory observables get their thermal properties from the bulk despite the absence of a black hole or cosmological horizon, with the role of the horizon played by the cosmological expansion of the de Sitter factor of the AdS metric.