Clusters in the disperse cosmic web

Abstract

ABSTRACT Galaxy cluster mass haloes (‘clusters’) in a dark matter simulation are matched to nodes in several different cosmic webs found using the disperse cosmic web finder. The webs have different simulation smoothings and disperse parameter choices; for each, four methods are considered for matching disperse nodes to clusters. For most of the webs, disperse nodes outnumber clusters, but not every cluster has a disperse node match (and sometimes >1 cluster matches to the same disperse node). The clusters frequently lacking a matching disperse node have a different distribution of local shear trends and perhaps merger histories. It might be interesting to see in what other ways, e.g. observational properties, these clusters differ. For the webs with smoothing ≤ 2.5 Mpc h−1, and all but the most restrictive matching criterion, ∼3/4 of the clusters always have a disperse node counterpart. The nearest cluster to a given disperse node and vice versa, within twice the smoothing length, obey a cluster mass-disperse node density relation. Cluster pairs where both clusters match disperse nodes can also be assigned the filaments between those nodes, but as the web and matching methods are varied most such filaments do not remain. There is an enhancement of subhalo counts and halo mass between cluster pairs, averaging over cluster pairs assigned disperse filaments increases the enhancement. The approach here also lends itself to comparing nodes across many cosmic web constructions, using the fixed underlying cluster distribution to make a correspondence.