Mass, light and colour of the cosmic web in the supercluster SCL2243-0935 ( z = 0.447)

Lietzen

Gramann

et al. 2016

A&A

Context. The formation and evolution of the cosmic web is governed by the gravitational attraction of dark matter and antigravity of dark energy (cosmological constant). In the cosmic web, galaxy superclusters or their high-density cores are the largest objects that may collapse at present or during the future evolution. Aims. We study the dynamical state and possible future evolution of galaxy superclusters from the Sloan Great Wall (SGW), the richest galaxy system in the nearby Universe. Methods. We calculated supercluster masses using dynamical masses of galaxy groups and stellar masses of galaxies. We employed normal mixture modelling to study the structure of rich SGW superclusters and search for components (cores) in superclusters. We analysed the radial mass distribution in the high-density cores of superclusters centred approximately at rich clusters and used the spherical collapse model to study their dynamical state. Results. The lower limit of the total mass of the SGW is approximately M = 2.5 × 10 16 h −1 M . Different mass estimators of superclusters agree well, the main uncertainties in masses of superclusters come from missing groups and clusters. We detected three high-density cores in the richest SGW supercluster (SCl 027) and two in the second richest supercluster (SCl 019). They have masses of 1.2−5.9 × 10 15 h −1 M and sizes of up to ≈60 h −1 Mpc. The high-density cores of superclusters are very elongated, flattened perpendicularly to the line of sight. The comparison of the radial mass distribution in the high-density cores with the predictions of spherical collapse model suggests that their central regions with radii smaller than 8 h −1 Mpc and masses of up to M = 2 × 10 15 h −1 M may be collapsing. Conclusions. The rich SGW superclusters with their high-density cores represent dynamically evolving environments for studies of the properties of galaxies and galaxy systems.

Section: Discussion and Summarymentioning

confidence: 70%

Section: Discussion and Summarymentioning

confidence: 99%

Sloan Great Wall as a complex of superclusters with collapsing cores

Lietzen

Gramann

et al. 2016

A&A

“…Few superclusters at very high redshifts have already been discovered in deep, wide-field imaging surveys (Nakata et al 2005;Swinbank et al 2007;Gal et al 2008;Tanaka et al 2009;Schirmer et al 2011). Deep surveys like the ALHAMBRA project (Moles et al 2008) will provide us with data about (possible) very distant superclusters; we can analyse their structure and compare that with the local superclusters, using morphological methods.…”

Section: Discussionmentioning

confidence: 99%

“…Superclusters are important tracers of dark and baryonic matter in the Universe (Zappacosta et al 2005;Génova-Santos et al 2005;Heymans et al 2008;Buote et al 2009;Padilla-Torres et al 2009;Schirmer et al 2011). Studies of superclusters and of the supercluster-void network have demonstrated the presence of a characteristic scale in the distribution of rich superclusters (Einasto et al 1994(Einasto et al , 1997a.…”

Section: Introductionmentioning

confidence: 99%

SDSS DR7 superclusters

Liivamägi

Tago

et al. 2011

A&A

122

Aims. We study the morphology of a set of superclusters drawn from the SDSS DR7. Methods. We calculate the luminosity density field to determine superclusters from a flux-limited sample of galaxies from SDSS DR7 and select superclusters with 300 and more galaxies for our study. We characterise the morphology of superclusters using the fourth Minkowski functional V 3 , the morphological signature (the curve in the shapefinder's K 1 -K 2 plane) and the shape parameter (the ratio of the shapefinders K 1 /K 2 ). We investigate the supercluster sample using multidimensional normal mixture modelling. We use Abell clusters to identify our superclusters with known superclusters and to study the large-scale distribution of superclusters. Results. The superclusters in our sample form three chains of superclusters; one of them is the Sloan Great Wall. Most superclusters have filament-like overall shapes. Superclusters can be divided into two sets; more elongated superclusters are more luminous, richer, have larger diameters and a more complex fine structure than less elongated superclusters. The fine structure of superclusters can be divided into four main morphological types: spiders, multispiders, filaments, and multibranching filaments. We present the 2D and 3D distribution of galaxies and rich groups, the fourth Minkowski functional, and the morphological signature for all superclusters. Conclusions. Widely different morphologies of superclusters show that their evolution has been dissimilar. A study of a larger sample of superclusters from observations and simulations is needed to understand the morphological variety of superclusters and the possible connection between the morphology of superclusters and their large-scale environment.

“…Superclusters, with their high-density environment and complex inner structure, are excellent laboratories with which to study the properties and evolution of galaxies and the groups of galaxies in them (Einasto et al 2007b(Einasto et al , 2008(Einasto et al , 2014Schirmer et al 2011;Swinbank et al 2007;Gal et al 2008;Faloon et al 2013;Krause et al 2013;Luparello et al 2013;Chon et al 2014;Chow-Martínez et al 2014;Lee et al 2015).…”

Section: Introductionmentioning

confidence: 99%

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

Gramann

Saar

et al. 2015

A&A

Context. Superclusters of galaxies can be used to test cosmological models of the formation and evolution of the largest structures in the cosmic web, and of galaxy and cluster evolution in superclusters. Aims. We study the distribution, masses, and dynamical properties of galaxy groups in the A2142 supercluster. Methods. We analyse the global luminosity density distribution in the supercluster and divide the supercluster into the high-density core and the low-density outskirts regions. We find galaxy groups and filaments in these regions, calculate their masses and mass-tolight ratios and analyse their dynamical state with 1D and 3D statistics. We use the spherical collapse model to study the dynamical state of the supercluster. Results. In the A2142 supercluster rich groups and clusters lie along an almost straight line forming the 50 h −1 Mpc long main body of the supercluster. The A2142 supercluster has a very high density core surrounded by lower-density outskirts. The total estimated mass of the supercluster is M est = 6.2 × 10 15 M . More than a half of groups with at least ten member galaxies in the supercluster lie in the high-density core of the supercluster, centred at the X-ray cluster A2142. Most of the groups in the core region are multimodal. In the outskirts of the supercluster, the number of groups is larger than in the core, and groups are poorer. The orientation of the axis of the cluster A2142 follows the orientations of its X-ray substructures and radio halo, and is aligned along the supercluster axis. The high-density core of the supercluster with the global density D8 ≥ 17 and perhaps with D8 ≥ 13 may have started to collapse. Conclusions. A2142 supercluster with collapsing core and straight body, is an unusual object among superclusters. In the course of the future evolution, the supercluster may split into several systems.