The richest superclusters

Abstract

Context. Superclusters are the largest systems in the Universe to give us information about the formation and evolution of structures in the very early Universe. Our present series of papers is devoted to the study of the morphology and internal structure of superclusters of galaxies. Aims. We study the morphology of the richest superclusters from the catalogs of superclusters of galaxies in the 2dF Galaxy Redshift Survey and compare the morphology of real superclusters with model superclusters in the Millennium Simulation. Methods. We use Minkowski functionals and shapefinders to quantify the morphology of superclusters: their sizes, shapes, and clumpiness. We generate empirical models of simple geometry to understand which morphologies correspond to the supercluster shapefinders (Appendix A). Results. Rich superclusters have elongated, filamentary shapes with high-density clumps in their core regions. The clumpiness of superclusters is determined using the fourth Minkowski functional V 3 . In the K 1 -K 2 shapefinder plane the morphology of superclusters is described by a curve which is characteristic of multi-branching filaments as shown by our empirical models. We found several differences between observed and model superclusters. The curves of the fourth Minkowski functional V 3 for observed and model superclusters have different shapes indicating that their structure is different. The values of V 3 for the supercluster SCL126 (the Sloan Great Wall) show that this supercluster has a very high density core which is absent in other superclusters. The values of the shapefinders H 1 -H 3 and K 1 and K 2 for observed superclusters have much larger scatter than for model superclusters. The differences between the fourth Minkowski functional V 3 for the bright and faint galaxies in observed superclusters are larger than in simulated superclusters. Conclusions. Our results show how the Minkowski functionals and shapefinders can be used to describe the morphology of superclusters: their shapes, sizes and clumpiness. The shapes of observed superclusters are more diverse than the shapes of simulated superclusters. The larger scatter of the fourth Minkowski functional V 3 for the bright and faint galaxies for observed superclusters compared to simulated superclusters is an indication that the clumpiness of bright and faint galaxies in models does not reflect well the clumpiness of different galaxies in observed superclusters. Our results suggest also that the volume covered by the Millennium Simulations may be too small to properly describe the large morphological variety of superclusters.

Unusual A2142 supercluster with a collapsing core: distribution of light and mass

“…In spiders there is a large number of galaxy chains between high-density cores in superclusters. Poor spider-type superclusters are similar to our Local Supercluster with one rich cluster and filaments of galaxies and poor groups of galaxies around it (Einasto et al 2007c). Einasto et al (2014) showed that galaxy content of filament-and spider-type superclusters differ: filament-type systems contain relatively more red, passive galaxies than spider-type systems.…”

“…The morphology of superclusters can be used as a test for cosmological models (Kolokotronis et al 2002;Einasto et al 2007a,c). The morphology of superclusters has been studied, for example, by Costa-Duarte et al (2011) and Einasto et al (2007c). Einasto et al (2007cEinasto et al ( , 2011c found in the large morphological variety of superclusters two main types A&A 580, A69 (2015) of superclusters, filaments and spiders.…”

“…The morphology of superclusters has been studied, for example, by Costa-Duarte et al (2011) and Einasto et al (2007c). Einasto et al (2007cEinasto et al ( , 2011c found in the large morphological variety of superclusters two main types A&A 580, A69 (2015) of superclusters, filaments and spiders. In filaments high-density core(s) of superclusters are connected by a small number of galaxy chains (filaments).…”

Sloan Great Wall as a complex of superclusters with collapsing cores

“…For example, while Park et al (2012) demonstrated that systems with sizes and richness similar to the SGW can be reproduced in the ΛCDM model, Sheth & Diaferio (2011) showed that systems as dense and massive as the SGW may be in tension with the Gaussian initial conditions. Moreover, Einasto et al (2007b) found that the morphology of the richest supercluster in the SGW is difficult to reproduce with simulations. Einasto et al (2016) showed that the superclusters from the SGW lie in a wall of a shell-like structure around the rich cluster A1795 in the Bootes supercluster with a radius of about 120−130 h −1 Mpc.…”

“…The SGW affects the measurements of the topology of the whole SDSS (Park et al 2005;Saar et al 2007;Gott et al 2008). The analysis of rich superclusters in the SGW has shown that they have a different morphology and galaxy and group content (Einasto et al 2007b(Einasto et al , 2010(Einasto et al , 2011a(Einasto et al ,b, 2014. The richest A&A 595, A70 (2016) supercluster in the SGW, SCl 027, is one of the most elongated superclusters according to its overall shape (Einasto et al 2011a).…”