Linking cluster formation to large-scale structure

We use two high-resolution cold dark matter (CDM) simulations to investigate how the formation of clusters of galaxies is related to the distribution of the surrounding mass. It is well known that in CDM universes objects grow in a hierarchical fashion. This process cannot be completely independent of its environment. We show that when clusters form the infall pattern is not random, but shows clear features, which are correlated in time. In addition, this infall pattern correlates with the large-scale structure (LSS) surrounding the cluster. Thus LSS not only exerts a tidal eld on clustering but also species preferred directions from which clusters are built up. We extend this point of view and study the distribution of mass outside the clusters. We nd that LSS shows a mix of both laments and sheets, which can be clearly identied using the representation chosen for this study. Filaments and sheets appear to be clumpy rather than homogeneous. Having identied laments we obtain mass estimates for them. We show that the mass fraction in laments is slightly larger in a low-density universe.