Abstract
The Perseus-Pisces supercluster is known as one of the largest structures in the nearby Universe that has been charted by the galaxy and galaxy cluster distributions. For the latter mostly clusters from the Abell catalogue have been used. Here we take a new approach to a quantitative characterisation of the Perseus-Pisces supercluster using a statistically complete sample of X-ray luminous galaxy groups and clusters from our CLASSIX galaxy cluster redshift survey. We used a friends-of-friends technique to construct the supercluster membership. We also studied the structure of the Southern Great Wall, which merges with the Perseus-Pisces supercluster with a slightly increased friends-of-friends linking length. In this work we discuss the geometric structure of the superclusters, compare the X-ray luminosity distribution of the members with that of the surroundings, and provide an estimate of the supercluster mass. These results establish Perseus-Pisces as the largest superstructure in the Universe at redshifts z ≤ 0.03. With the new data this supercluster extends through the zone of avoidance, which has also been indicated by some studies of the galaxy distribution by means of HI observations. We investigated whether the shapes of the member groups and clusters in X-rays are aligned with the major axis of the supercluster. We find no evidence for a pronounced alignment, except for the ellipticities of Perseus and AWM7, which are aligned with the separation vector of the two systems and weakly with the supercluster.
Highlights
The large-scale structure of the Universe is often described as the cosmic web traced by galaxies and galaxy clusters
We introduced a clearer definition of superclusters at higher overdensities, comprising those supercluster mass distributions that will collapse in the future in a Λ cold dark matter (ΛCDM) Universe, calling them superstes-clusters (Chon et al 2015
Constructing SCs in the local Universe (z ≤ 0.03) in the region around the Perseus-Pisces SC with a minimum linking length of l0 = Mpc, we find Cosmic Large-Scale Structure in X-rays (CLASSIX) members defining the Perseus-Pisces SC
Summary
The large-scale structure of the Universe is often described as the cosmic web traced by galaxies and galaxy clusters. We introduced a clearer definition of superclusters at higher overdensities, comprising those supercluster mass distributions that will collapse in the future in a Λ cold dark matter (ΛCDM) Universe, calling them superstes-clusters (Chon et al 2015). We introduced a clearer definition of superclusters at higher overdensities, comprising those supercluster mass distributions that will collapse in the future in a Λ cold dark matter (ΛCDM) Universe, calling them superstes-clusters (Chon et al 2015)1 Structures larger than this will be transient phenomena in the long run and we refer to them here as superclusters. They are still in the regime of non-linear structures, as reflected in their flattened or filamentary shapes and overdensities well exceeding unity.
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