### [1007.0742] Multiscale Phenomenology of the Cosmic Web

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**July 14 2010**I enjoyed reading this paper on the shapes of cosmic structures. The authors take an N-body simulation with 150 [tex]h^{-1}[/tex]Mpc on a side (which they consider large, but I would rather call the size moderate, as it's not much larger than the observed homogeneity scale), and produce a density field from the point distribution using a Delaunay tessellation. This continuous field is then analysed on different scales to put together a multiscale picture (in a manner I didn't quite understand).

In addition to providing nice visualisations, the method provides (among other statistical quantities) an inventory of cosmic structures in terms of clusters, filaments, walls and voids, with percentages of mass and volume. It's clear that the precise numbers depend on the adopted definitions, but at least one can get some idea. The authors emphasise that these features overlap in terms of density (which highlights the role of shear in structure formation).

An analysis of the density profiles of filaments in the direction orthogonal to the filament was an interesting application as well.

In addition to providing nice visualisations, the method provides (among other statistical quantities) an inventory of cosmic structures in terms of clusters, filaments, walls and voids, with percentages of mass and volume. It's clear that the precise numbers depend on the adopted definitions, but at least one can get some idea. The authors emphasise that these features overlap in terms of density (which highlights the role of shear in structure formation).

An analysis of the density profiles of filaments in the direction orthogonal to the filament was an interesting application as well.