Holography and black holes in asymptotically flat FLRW

Abstract: In this paper, we extend the treatment of asymptotically decelerating spatially flat FLRW spacetimes initiated in [1]. We show that a certain class of those metrics is ruled by the asymptotic algebra $\mathfrak{b}\mathfrak{m}\mathfrak{s}_s$, which belongs to a one-parameter family of deformations of $\mathfrak{b}\mathfrak{m}\mathfrak{s}$. Furthermore, we enlarge our ansatz to include $\text{Diff}(S^2)$ transformations whose asymptotic algebra $\mathfrak{g}\mathfrak{b}\mathfrak{m}\mathfrak{s}_s$ is a one parameter deformation of $\mathfrak{g}\mathfrak{b}\mathfrak{m}\mathfrak{s}$. Therefore, the holographic algebras $\mathfrak{b}\mathfrak{m}\mathfrak{s}_s$ and $\mathfrak{g}\mathfrak{b}\mathfrak{m}\mathfrak{s}_s$ in FLRW can be related to their flat counterparts through a cosmological holographic flow. Finally, we introduce a logarithmic ansatz in order to account for cosmological black holes, which does not generally satisfy the peeling property but preserves the asymptotic algebra.