Supercluster A2142 and collapse in action: infalling and merging groups and galaxy transformations

Einasto, M.; Gramann, Mirt; Park, Changbom; Kim, Juhan; Deshev, Boris; Tempel, Elmo; Heinämäki, P.; Lietzen, H.; Lähteenmäki, A.; Einasto, J.; Saar, E.

doi:10.1051/0004-6361/201833711

Cited by 22 publications

(51 citation statements)

References 131 publications

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“…The tail as a whole resembles the thick filament described in Cautun et al (2013). Earlier studies have shown that the supercluster main body is already collapsing or will collapse in the future (Einasto et al 2015;Gramann et al 2015;Einasto et al 2018c).…”

Section: Introductionmentioning

confidence: 69%

“…Nine such groups lie in the HDC of the supercluster, and 12 lie at the supercluster axis along an almost straight line. These groups in the supercluster, their galaxy content, and dynamical state were analysed in Einasto et al (2018c). We highlight groups with at least ten galaxies in the cocoon to compare the properties of groups in both environments.…”

Section: Filaments and Groups In The Supercluster And In The Cocoonmentioning

confidence: 99%

“…However, groups C1-C4 have less than 20 galaxies, and it is not straightforward to analyse their substructure (as shown, for example, by Ribeiro et al 2013). They lie away from each other and do not form possibly merging group pairs, as do some groups in the supercluster along the supercluster tail (Einasto et al 2018c). Thus, we use magnitude gap between group's two brightest galaxies, |∆M 12 | as an indicator of their evolutionary state (Dariush et al 2010;Kanagusuku et al 2016).…”

Section: Filaments and Groups In The Supercluster And In The Cocoonmentioning

confidence: 99%

“…Simulations show that present-day rich clusters have collected their galaxies along filaments from regions with comoving radii at least 10 h −1 Mpc at redshift z = 1 (Chiang et al 2013;Overzier 2016). The formation of clusters is accompanied by the star-formation quenching of galaxies when they fall into clusters (Haines et al 2015;Einasto et al 2018c;Musso et al 2018;Kraljic et al 2019;Maier et al 2019;Trussler et al 2020). One result of galaxy quenching and morphological transformations is the large-scale morphological segregation of galaxies at low and high redshifts.…”

Section: Introductionmentioning

confidence: 99%

“…In this paper, we use, as in Einasto et al (2018c), data from the Sloan Digital Sky Survey data release 10 (SDSS DR10) to analyse the structure and properties of galaxies and galaxy systems in the cocoon of SCl A2142 (Aihara et al 2011;Ahn et al 2014). In accordance with the earlier studies of the A2142 supercluster, we use the following cosmological parameters: the Hubble parameter H 0 = 100 h km s −1 Mpc −1 , matter density Ω m = 0.27, and dark energy density Ω Λ = 0.73 (Komatsu et al 2011).…”

Section: Introductionmentioning

confidence: 99%

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Multiscale cosmic web detachments, connectivity, and preprocessing in the supercluster SCl A2142 cocoon

Einasto

Deshev

Tenjes

et al. 2020

A&A

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Context. Superclusters of galaxies and their surrounding low-density regions (cocoons) represent dynamically evolving environments in which galaxies and their systems form and evolve. While evolutionary processes of galaxies in dense environments are extensively studied at present, galaxy evolution in low-density regions has received less attention. Aims. We study the properties, connectivity, and galaxy content of groups and filaments in the A2142 supercluster (SCl A2142) cocoon to understand the evolution of the supercluster with its surrounding structures and the galaxies within them. Methods. We calculated the luminosity-density field of SDSS galaxies and traced the SCl A2142 cocoon boundaries by the lowest luminosity-density regions that separate SCl A2142 from other superclusters. We determined galaxy filaments and groups in the cocoon and analysed the connectivity of groups, the high density core (HDC) of the supercluster, and the whole of the supercluster. We compared the distribution and properties of galaxies with different star-formation properties in the supercluster and in the cocoon. Results. The supercluster A2142 and the long filament that is connected to it forms the longest straight structure in the Universe detected so far, with a length of approximately 75 h −1 Mpc. The connectivity of the cluster A2142 and the whole supercluster is C = 6 − 7; poor groups exhibit C = 1 − 2. Long filaments around the supercluster's main body are detached from it at the turnaround region. Among various local and global environmental trends with regard to the properties of galaxies and groups, we find that galaxies with very old stellar populations lie in systems across a wide range of richness from the richest cluster to poorest groups and single galaxies. They lie even at local densities as low as D1 < 1 in the cocoon and up to D1 > 800 in the supercluster. Recently quenched galaxies lie in the cocoon mainly in one region and their properties are different in the cocoon and in the supercluster. The star-formation properties of single galaxies are similar across all environments. Conclusions. The collapsing main body of SCl A2142 with the detached long filaments near it are evidence of an important epoch in the supercluster evolution. There is a need for further studies to explore possible reasons behind the similarities between galaxies with very old stellar populations in extremely different environments, as well as mechanisms for galaxy quenching at very low densities. The presence of long, straight structures in the cosmic web may serve as a test for cosmological models.

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Section: Introductionmentioning

confidence: 69%

Section: Filaments and Groups In The Supercluster And In The Cocoonmentioning

confidence: 99%

Section: Filaments and Groups In The Supercluster And In The Cocoonmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Multiscale cosmic web detachments, connectivity, and preprocessing in the supercluster SCl A2142 cocoon

Einasto

Deshev

Tenjes

et al. 2020

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Probing the azimuthal environment of galaxies around clusters

Gouin

Aghanim

Bonjean

et al. 2020

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Galaxy clusters are connected at their peripheries to the large scale structures by cosmic filaments that funnel accreting material. These filamentary structures are studied to investigate both environment-driven galaxy evolution and structure formation and evolution. In the present work, we probe in a statistical manner the azimuthal distribution of galaxies around clusters as a function of the cluster-centric distance, the cluster richness, and the galaxy activity (star-forming or passive). We perform a harmonic decomposition in large photometric galaxy catalogue around 6400 SDSS clusters with masses M > 10 14 solar masses, in the redshift range of 0.1 < z < 0.3. The same analysis is performed on the mock galaxy catalogue from the light-cone of Magneticum hydrodynamical simulation. We use the multipole analysis to quantify asymmetries in the 2-D galaxy distribution. In the inner cluster regions at R < 2R500, we confirm that the galaxy distribution traces an ellipsoidal shape, which is more pronounced for richest clusters. In the clusters' outskirts (R = [2 − 8]R500), filamentary patterns are detected in harmonic space with a mean angular scale mmean = 4.2 ± 0.1. Massive clusters seem to have a larger number of connected filaments than low massive ones. We also find that passive galaxies appear to better trace the filamentary structures around clusters, even if the contribution of SF ones tend to increase with the cluster-centric distance, suggesting a gradient of galaxy activity in filaments around clusters.

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Mapping the working of environmental effects in A963

Deshev

Haines

Hwang

et al. 2020

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Aims. We qualitatively assess and map the relative contribution of pre-processing and cluster related processes to the build-up of A963, a massive cluster at z = 0.2 showing an unusually high fraction of star forming galaxies in its interior. Methods. We use Voronoi binning of positions of cluster members on the plane of the sky in order to map the 2D variations of galaxy properties in the centre and infall region of A963. We map four galaxy parameters (fraction of star forming galaxies, specific star formation rate, H I deficiency and age of the stellar population) based on full SED fitting, 21 cm imaging and optical spectroscopy. Results. We find an extended region dominated by passive galaxies along a north–south axis crossing the cluster centre, possibly associated with known filaments of the large-scale structure. There are signs that the passive galaxies in this region were quenched long before their arrival in the vicinity of the cluster. Contrary to that, to the east and west of the cluster centre lie regions of recent accretion dominated by gas rich, actively star forming galaxies not associated with any substructure or filament. The few passive galaxies in this region appear to be recently quenched, and some gas rich galaxies show signs of ongoing ram-pressure stripping. We report the first tentative observations at 21 cm of ongoing ram-pressure stripping at z = 0.2, as well as observed inflow of low-entropy gas into the cluster along filaments of the large-scale structure. Conclusions. The observed galaxy content of A963 is a result of strongly anisotropic accretion of galaxies with different properties. Gas rich, star forming galaxies are being accreted from the east and west of the cluster and these galaxies are being quenched at r < R200, likely by ram-pressure stripping. The bulk of the accretion onto the cluster, containing multiple groups, happens along the north–south axis and brings mostly passive galaxies, likely quenched before entering A963.

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Supercluster A2142 and collapse in action: infalling and merging groups and galaxy transformations

Cited by 22 publications

References 131 publications

Multiscale cosmic web detachments, connectivity, and preprocessing in the supercluster SCl A2142 cocoon

Multiscale cosmic web detachments, connectivity, and preprocessing in the supercluster SCl A2142 cocoon

Probing the azimuthal environment of galaxies around clusters

Mapping the working of environmental effects in A963

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