Evolution of superclusters in the cosmic web

Einasto, J.; Suhhonenko, I.; Liivamägi, L. J.; Einasto, M.

doi:10.1051/0004-6361/201834450

Cited by 26 publications

(51 citation statements)

References 50 publications

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“…The essential evolution of superclusters and their components occurs inside supercluster cocoons (Einasto et al 2019). 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).…”

Section: Introductionmentioning

confidence: 99%

“…According to this definition, a supercluster is defined as the structure inside its basin of attraction and different superclusters are separated by the minima in the velocity field around them. To keep the term 'supercluster' tied to its conventional meaning as a high-density region in the cosmic web, Einasto et al (2019) proposed calling low-density regions around conventional superclusters supercluster cocoons. Supercluster cocoons, together with embedded superclusters, correspond to the regions of the dynamical influence, as defined by Tully et al (2014).…”

Section: Introductionmentioning

confidence: 99%

“…Density field minima correspond to the minima in the velocity field, where peculiar velocities of galaxies are equal to 0 (so-called linear or the Einstein-Straus scale, Nusser et al 1991;Teerikorpi et al 2015). Superclusters occupy only approximately 1% of the total volume, while 99% of the total volume is occupied by cocoons (Einasto et al 2019).…”

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: 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

A&A

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“…Studies of the evolution of the superstructure network show that although some small systems may have undergone merger events with other superstructures during their past assembly history, this is not a dominant factor on the global evolution. Rather, the main transformation processes takes place inside the systems (Einasto et al 2019). Different attempts to provide useful characterization of the large-scale structure have been performed either using the galaxy distribution (Tegmark et al 2004;Scottez et al 2016) as well as studying large scale galaxy system properties such as superclusters, clusters, filaments and voids (Colberg et al 2000;Brodwin et al 2007;Chan et al 2014).…”

Section: Motivationmentioning

confidence: 99%

Spatial correlations of extended cosmological structures

Santucho

Luparello

Lares

et al. 2020

Monthly Notices of the Royal Astronomical Society

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Studies of large-scale structures in the Universe, such as superstructures or cosmic voids, have been widely used to characterize the properties of the cosmic web through statistical analyses. On the other hand, the 2-point correlation function of large-scale tracers such as galaxies or halos provides a reliable statistical measure. However, this function applies to the spatial distribution of point-like objects, and therefore it is not appropriate for extended large structures which strongly depart from spherical symmetry. Here we present an analysis based on the standard correlation function formalism that can be applied to extended objects exhibiting arbitrary shapes. Following this approach, we compute the probability excess Ξ of having spheres sharing parts of cosmic structures with respect to a realization corresponding to a distribution of the same structures in random positions. For this aim, we identify superstructures defined as Future Virialized Structures (FVSs) in semi-anaytic galaxies on the MPDL2 MultiDark simulation. We have also identified cosmic voids to provide a joint study of their relative distribution with respect to the superstructures. Our analysis suggests that Ξ provides useful characterizations of the large scale distribution, as suggested from an analysis of sub-sets of the simulation. Even when superstructure properties may exhibit negligible variations across the sub-sets, Ξ has the sensitivity to statistically distinguish sub-boxes that departs from the mean at larger scales. Thus, our methods can be applied in analysis of future surveys to provide characterizations of large-scale structure suitable to distinguish different theoretical scenarios.

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“…This scale is close to the BAO scale and the scale found by Broadhurst et al (1990) in the distribution of galaxies in narrow beams, and by Einasto et al (1994Einasto et al ( , 1997cEinasto et al ( , 2016 in the distribution of rich clusters of galaxies. On the other hand, samples of size about 1000 h −1 Mpc are needed to get a representative sample of very rich superclusters and supercluster complexes of the Sloan Great Wall type, as shown by Klypin & Prada (2019) and Einasto et al (2019b).…”

Section: Zero Crossing Of Correlation Functionsmentioning

confidence: 99%

Correlation function: biasing and fractal properties of the cosmic web

Einasto,

Hütsi,

Kuutma

et al. 2020

Preprint

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Aims. Our goal is to find how the spatial correlation function of galaxies describes the multifractal nature of the cosmic web. Methods. We calculate spatial correlation functions of galaxies, ξ(r), structure functions, g(r) = 1 + ξ(r), and fractal dimension functions, D(x) = 3 + γ(r) = 3 + d log g(r)/d log r, using dark matter particles of biased Λ cold dark matter (CDM) simulation, observed galaxies of the Sloan Digital Sky Survey (SDSS), and simulated galaxies of the Millennium and EAGLE simulations. We analyse how these functions describe fractal and other geometrical properties of the cosmic web. Results. Correlation functions of biased ΛCDM model samples describe at small distances (particle/galaxy separations), r ≤ 2.25 h −1 Mpc, the distribution of matter inside DM halos. In real and simulated galaxy samples only brightest galaxies in clusters are visible, and the transition from clusters to filaments occurs at distance r ≈ 0.8 − 1.5 h −1 Mpc. On larger separations correlation functions describe the distribution of matter and galaxies in the whole cosmic web. The effective fractal dimension of the cosmic web is a continuous function of the distance (separation). On small separations, r ≤ 2 h −1 Mpc, the fractal dimension decreases from D ≈ 1.5 to D ≈ 0, reflecting the distribution inside halos/clusters. The minimum of the fractal dimension function D(r) near r ≈ 2 is deeper for more luminous galaxies. On medium separations, 2 ≤ r ≤ 10 h −1 Mpc, the fractal dimension grows from ≈ 0 to ≈ 2, and approaches at large separations 3 (random distribution). Real and simulated galaxies of low luminosity, M r ≥ −19, have almost identical correlation lengths and amplitudes, indicating that dwarf galaxies are satellites of brighter galaxies, and do not form a smooth population in voids. Conclusions. Spatial correlation functions of galaxies contain valuable information on fractal dimension and other geometrical properties of the cosmic web.

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Evolution of superclusters in the cosmic web

Cited by 26 publications

References 50 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

Spatial correlations of extended cosmological structures

Correlation function: biasing and fractal properties of the cosmic web

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