Superclusters of galaxies from the 2dF redshift survey

Einasto, J.; Einasto, M.; Tago, E.; Saar, E.; Hütsi, Gert; Jôeveer, Mihkel; Liivamägi, L. J.; Suhhonenko, I.; Jaaniste, J.; Heinämäki, P.; Müller, V.; Knebe, Alexander; Tucker, D. L.

doi:10.1051/0004-6361:20065296

Cited by 93 publications

(126 citation statements)

References 61 publications

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“…We used the B 3 spline kernel to calculate the density field. We chose a 8 h −1 Mpc scale smoothing for global densities (Einasto et al 2007). Details of the density calculation are given in Liivamägi et al (2011).…”

Section: Determining Environmental Densitiesmentioning

confidence: 99%

Galaxy morphology, luminosity, and environment in the SDSS DR7

Tempel

Saar

Liivamägi

et al. 2011

A&A

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Aims. We study the influence of the environment on the evolution of galaxies by investigating the luminosity function (LF) of galaxies of different morphological types and colours at different environmental density levels. Methods. We construct the LFs separately for galaxies of different morphology (spiral and elliptical) and of different colours (red and blue) using data from the Sloan Digital Sky Survey (SDSS), correcting the luminosities for the intrinsic absorption. We use the global luminosity density field to define different environments, and analyse the environmental dependence of galaxy morphology and colour. The smoothed bootstrap method is used to calculate confidence regions of the derived luminosity functions. Results. We find a strong environmental dependency for the LF of elliptical galaxies. The LF of spiral galaxies is almost environment independent, suggesting that spiral galaxy formation mechanisms are similar in different environments. Absorption by the intrinsic dust influences the bright-end of the LF of spiral galaxies. After attenuation correction, the brightest spiral galaxies are still about 0.5 mag less luminous than the brightest elliptical galaxies, except in the least dense environment, where spiral galaxies dominate the LF at every luminosity. Despite the extent of the SDSS survey, the influence of single rich superclusters is present in the galactic LF of the densest environment.

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Section: Determining Environmental Densitiesmentioning

confidence: 99%

Galaxy morphology, luminosity, and environment in the SDSS DR7

Tempel

Saar

Liivamägi

et al. 2011

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“…It has been shown that the morphological properties of galaxies depend on their large-scale cosmological environment (Einasto et al 2007a, and references therein). Both the local (group or cluster scale) and global (supercluster scale) environments influence galaxy morphology and their star-formation activity.…”

Section: Superclusters and Quasarsmentioning

confidence: 99%

“…The half-width of the B3 smoothing kernel was 16 h −1 Mpc, and the effective smoothing radius (the kernel halfwidth for which the density value differs considerably from zero) is 8 h −1 Mpc. This is an appropriate value for characterizing the global environment and superclusters (Einasto et al 2007a).…”

Section: Superclusters and Quasarsmentioning

confidence: 99%

Environments of nearby quasars in Sloan Digital Sky Survey

Lietzen

Heinämäki

Nurmi

et al. 2009

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Context. For the first time, spectroscopic galaxy redshift surveys are enabling galaxies to be studied with the nearest quasars. This allows the dependence of the activity of a quasar on its environment to be studied in a more extensive way than before. Aims. We study the spatial distribution of galaxies and properties of groups of galaxies in the environments of low redshift quasars in the Sloan Digital Sky Survey (SDSS). Our aim is to understand how the nearby quasars are embedded in the local and global density field of galaxies and how the environment affects quasar activity. Methods. We analyze the environments of nearby quasars using number counts of galaxies. We also study the dependence of group properties on their distance to the nearest quasar. The large-scale environments are studied by analyzing the locations of quasars in the luminosity density field. Results. Our study of the number counts of galaxies in quasar environments shows an underdensity of bright galaxies at a few Mpc from quasars. Groups of galaxies with a quasar closer than 2 Mpc are also poorer and less luminous than average. Our analysis of the luminosity density field shows that quasars clearly avoid rich superclusters. Nearby quasars seem to be located in the outskirts of superclusters or in the filaments connecting them. Conclusions. Our results suggest that quasar evolution may be affected by density variations both on supercluster scales and in the local environment.

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“…Recent deep surveys of galaxies (as 2dFGRS and SDSS, see Colless et al 2003;Abazajian et al 2009) introduced a new era in the studies of the large-scale structure of the Universe, where systems of galaxies can be studied in unprecedended detail. A number of supercluster catalogues have been compiled with these data (Basilakos 2003;Einasto et al 2003a;Erdogdu et al 2004;Einasto et al 2006Einasto et al , 2007bLiivamägi et al 2010;Luparello et al 2011, and references therein).…”

Section: Introductionmentioning

confidence: 99%

SDSS DR7 superclusters

Einasto

Liivamägi

Tago

et al. 2011

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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.

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Superclusters of galaxies from the 2dF redshift survey

Cited by 93 publications

References 61 publications

Galaxy morphology, luminosity, and environment in the SDSS DR7

Galaxy morphology, luminosity, and environment in the SDSS DR7

Environments of nearby quasars in Sloan Digital Sky Survey

SDSS DR7 superclusters

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