The Hidden Role of Anisotropies in Shaping Structure Formation in Cosmological N-Body Simulations by Francesco Sylos Labini, Physical Review D in the press

In this work we show that the formation of filaments in cosmological N-body simulations arises from the amplification of anisotropies already present in the initial conditions. Such anisotropies should not occur if the initial conditions correctly reproduce the density field predicted by standard cosmological models, namely a uniform and statistically isotropic field.

We therefore conclude that the filamentary structures observed in cosmological N-body simulations are largely spurious, in the sense that they reflect artefacts of the initial conditions rather than genuine outcomes of the underlying cosmological models. To reach these conclusions, we have developed a new statistical tool—the angular distribution of pairwise distances and its scale-dependent variance—which is capable of identifying filamentary structures and relating observational measurements unambiguously to theoretical predictions.