Vacuum Fluctuations as Quantum Probes in FRWL space-times

Vacuum fluctuations related a massless conformally coupled scalar field in Friedman-Robertson-Walker-Lemaitre (FRWL) space-times are investigated. Point-slitting regularization is used and a specific renormalization proposal is discussed. Applications to generic black holes and FRWL form of the de Sitter space-time are presented.