  In the holographic description of cosmic preheating proposed in an
accompanied Letter [1], the energy transfer between the inflaton and matter
field at strong coupling is suggested to be mimicked by superfluid and normal
components of a superconductor on Friedmann-Robertson-Walker (FRW) boundary in
an asymptotically Anti-de Sitter (AdS) spacetime. In this paper we investigated
two aspects of the scenario of holographic preheating that are not included in
the accompanied work. Firstly, we study in detail the evolution of the
quasi-normal modes (QNMs) surrounding a metastable hairy black hole. This
analysis can quantitatively describe the preheating process of the matter field
that is produced continuously in the case of strong coupling. Secondly, we
present a detailed analysis of the holographic renormalization for the AdS-FRW
background, which allows us to extract operator expectation values for studying
cosmological implications.
