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

Abstract

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.

Sloan Great Wall as a complex of superclusters with collapsing cores

“…Johnston-Hollitt et al 2008;Schirmer et al 2011;Pompei et al 2016;Einasto et al 2015). They are lower than the masses of very rich superclusters such as the Shapley supercluster, the Corona Borealis supercluster, and other very rich superclusters (Reisenegger et al 2000;Proust et al 2006;Ragone et al 2006;Pearson et al 2014;O'Mill et al 2015).…”

“…To obtain a dynamical mass of a supercluster M dyn , we summed group dynamical masses. A similar procedure to calculate the dynamical mass of the supercluster was used in Einasto et al (2015). The reliability of group mass estimation method and mass errors were analysed in Old et al (2014Old et al ( , 2015, where various mass estimation methods were tested on mock galaxy catalogues.…”

“…The structure of the superclusters is formed during a hierarchical evolution where the high-density cores of superclusters are older and dynamically more evolved than outskirts regions. While full rich superclusters are not bound systems, their high-density cores may collapse at present or in the course of the future evolution (Small et al 1998;Reisenegger et al 2000;Rines et al 2002;Nagamine & Loeb 2003;Proust et al 2006;Dünner et al 2006;Luparello et al 2011;Pearson et al 2014;Chon et al 2015;O'Mill et al 2015;Einasto et al 2015;Gramann et al 2015). This makes galaxy superclusters unique objects to study their properties and the properties and evolution of the galaxy systems (groups, clusters, and filaments) inside the dynamically evolving environment of superclusters.…”

Does the Corona Borealis Supercluster form a giant binary-like system?

“…On the contrary, if an observed turnaround radius would turn out greater than R ta,max , this would violate the ΛCDM model. Since superclusters are expected to fit positions of maximum density contrast inside the cluster distribution, to identify their membership and mass, R , the mass estimation has been evaluated as in Einasto et al (2015) where the estimate is provided by the dynamical mass summation of all objects included in sph R . Einasto et al (2015) distinguished between two mass estimates: first, the dynamical mass summation of groups and clusters within a certain radius including also triplets and pairs evaluated by the median of each corresponding sample in order to reduce the large uncertainty (so did we).…”

“…Since superclusters are expected to fit positions of maximum density contrast inside the cluster distribution, to identify their membership and mass, R , the mass estimation has been evaluated as in Einasto et al (2015) where the estimate is provided by the dynamical mass summation of all objects included in sph R . Einasto et al (2015) distinguished between two mass estimates: first, the dynamical mass summation of groups and clusters within a certain radius including also triplets and pairs evaluated by the median of each corresponding sample in order to reduce the large uncertainty (so did we). Second, they added to the first estimate the estimated mass of the intra-cluster gas (10% of the total mass) and masses of faint groups which are not detected by the limit of the T14 Catalog, but predicted by the brightest galaxies present in the region.…”