Superclusters of galaxies in the 2dF redshift survey. 3. The properties of galaxies in superclusters (original) (raw)

Superclusters of galaxies in the 2dF redshift survey

Astronomy & Astrophysics, 2007

Context. Superclusters are the largest systems in the Universe to give us information about the very early Universe. Our present series of papers is devoted to the study of the properties of superclusters of galaxies from the 2dF Galaxy Redshift survey. Aims. We use catalogues of superclusters of galaxies from the 2dF Galaxy Redshift Survey to compare the properties of rich and poor superclusters. In particular, we study the properties of galaxies (spectral types, colours, and luminosities) in superclusters. Methods. We compare the distribution of densities in rich and poor superclusters, and the properties of galaxies in high and lowdensity regions of rich superclusters, in poor superclusters, and in the field. In superclusters and in the field, we also compare the properties of galaxies in groups, and the properties of those galaxies which do not belong to any group. Results. We show that in rich superclusters the values of the luminosity density smoothed on a scale of 8 h −1 Mpc are higher than in poor superclusters: the median density in rich superclusters is δ ≈ 7.5 and in poor superclusters δ ≈ 6.0. Rich superclusters contain high-density cores with densities δ > 10, while in poor superclusters such high-density cores are absent. The properties of galaxies in rich and poor superclusters and in the field are different: the fraction of early type, passive galaxies in rich superclusters is slightly higher than in poor superclusters, and is the lowest among the field galaxies. Most importantly, in high-density cores of rich superclusters (δ > 10), there is an excess of early type, passive galaxies in groups and clusters, as well as among those which do not belong to any group. The main galaxies of superclusters have a rather limited range of absolute magnitudes. The main galaxies of rich superclusters have higher luminosities than those of poor superclusters and of groups in the field. Conclusions. Our results show that both the local (group/cluster) environments and global (supercluster) environments influence galaxy morphologies and their star formation activity.

The richest superclusters. II. Galaxy populations

Aims. We study the morphology of galaxy populations of the richest superclusters from the catalogue of superclusters of galaxies in the 2dF Galaxy Redshift Survey. Methods. We use the luminosity density distribution and Minkowski functional V 3 to study substructures in superclusters as formed by different populations of galaxies. We compare the properties of grouped and isolated galaxies in regions of different density in superclusters.

Clusters and superclusters of galaxies

Rich clusters of galaxies are the most massive virialized systems known. Even though they contain only a small fraction of all galaxies, rich clusters provide a powerful tool for the study of galaxy formation, dark matter, large-scale structure, and cosmology.

SDSS superclusters: morphology and galaxy content

Astronomy & Astrophysics, 2014

Context. Understanding the formation, evolution and present-day properties of the cosmic web and objects forming it is an important task in cosmology. Aims. We compare the galaxy populations in superclusters of different morphology in the nearby Universe (180 h −1 Mpc ≤ d ≤ 270 h −1 Mpc) to see whether the inner structure and overall morphology of superclusters are important in shaping galaxy properties in superclusters. Methods. We find supercluster morphology with Minkowski functionals and analyse the probability density distributions of colours, morphological types, stellar masses, star formation rate (SFR) of galaxies, and the peculiar velocities of the main galaxies in groups in superclusters of filament and spider types, and in the field. We test the statistical significance of the results with the KS test.

Superclusters of galaxies from the 2dF redshift survey

Astronomy and Astrophysics, 2007

We use the 2dF Galaxy Redshift Survey data to compile catalogues of superclusters for the Northern and Southern regions of the 2dFGRS, altogether 543 superclusters at redshifts 0.009 ≤ z ≤ 0.2. We analyse methods of compiling supercluster catalogues and use results of the Millennium Simulation to investigate possible selection effects and errors. We find that the most effective method is the density field method using smoothing with an Epanechnikov kernel of radius 8 h −1 Mpc. We derive positions of the highest luminosity density peaks and find the most luminous cluster in the vicinity of the peak, this cluster is considered as the main cluster and its brightest galaxy the main galaxy of the supercluster. In catalogues we give equatorial coordinates and distances of superclusters as determined by positions of their main clusters. We also calculate the expected total luminosities of the superclusters.

Environments of galaxies in groups within the supercluster-void network

Astronomy & Astrophysics, 2012

Context. The majority of all galaxies reside in groups of fewer than 50 member galaxies. These groups are distributed in various large-scale environments from voids to superclusters. Aims. The evolution of galaxies is affected by the environment in which they reside. Our aim is to study the effects of the local group scale and the supercluster scale environments on galaxy evolution. Methods. We use a luminosity-density field to determine the density of the large-scale environment of galaxies in groups of various richnesses. We calculate the fractions of different types of galaxies in groups with richnesses of up to 50 member galaxies and in different large-scale environments from voids to superclusters. Results. The fraction of passive elliptical galaxies rises and the fraction of star-forming spiral galaxies declines when the richness of a group of galaxies rises from two to approximately ten galaxies. On large scales, passive elliptical galaxies become more numerous than star-forming spirals when the environmental density grows to values typical of superclusters. The large-scale environment affects the level of these fractions in groups: galaxies in equally rich groups are more likely to be elliptical in supercluster environments than at lower densities. The crossing point, where the number of passive and star-forming galaxies is equal, occurs in superclusters in groups that are of lower richness than in voids. Galaxies in low-density environments need to occupy richer groups to evolve from star-forming to passive than galaxies in high-density environments. Groups in superclusters are on average more luminous than groups in large-scale environments of lower density. These results imply that the large-scale environment affects the properties of galaxies and groups. Conclusions. Our results suggest that the evolution of galaxies is affected by both, the group in which the galaxy resides and its largescale environment. Galaxies in lower-density regions develop later than galaxies in similar mass groups in high-density environments.

Clusters and superclusters in the Las Campanas redshift survey

Astronomy and Astrophysics, 2003

We use a 2-dimensional high-resolution density field of galaxies of the Las Campanas Redshift Survey (LCRS) with a smoothing length 0.8 h −1 Mpc to extract clusters and groups of galaxies, and a low-resolution field with a smoothing length 10 h −1 Mpc to find superclusters of galaxies. We study the properties of these density field (DF) clusters and superclusters, and compare the properties of the DF-clusters and superclusters with those of Abell clusters and superclusters and LCRS groups. We show that among the cluster samples studied the DF-cluster sample best describes the large-scale distribution of matter and the fine structure of superclusters. We calculate the DF-cluster luminosity function and find that clusters in high-density environments are about ten times more luminous than those in low-density environments. We show that the DF-superclusters that contain Abell clusters are richer and more luminous than the DF-superclusters without Abell clusters. The distribution of DF-clusters and superclusters shows the hierarchy of systems in the universe.

The morphological types of galaxies in the Local Supercluster

Proceedings of the International Astronomical Union, 2014

On the basis of the Hyper – Leda Catalogue HyperLeda 8293 galaxies with heliocentric radial velocities below 2500 km s-1 were selected; 4570 had known morphological types (4366 had calculated b/a ratio). We checked the frequency of the distribution of various types in the LSC, finding spirals and irregulars most numerous, in accordance with expectations. The axial ratio of galaxy diameters of various types was studied, and the dependence of this parameter on the morphological type was noted.

(DOI: will be inserted by hand later) Clusters and Superclusters in the Las Campanas Redshift Survey

2003

Abstract. We use a 2-dimensional high-resolution density field of galaxies of the Las Campanas Redshift Survey (LCRS) with a smoothing length 0.8 h −1 Mpc to extract clusters and groups of galaxies, and a low-resolution field with a smoothing length 10 h −1 Mpc to find superclusters of galaxies. We study the properties of these density field (DF) clusters and superclusters, and compare the properties of the DF-clusters and superclusters with those of Abell clusters and superclusters and LCRS groups. We show that among the cluster samples studied the DF-cluster sample best describes the large-scale distribution of matter and the fine structure of superclusters. We calculate the DF-cluster luminosity function and find that clusters in high-density environments are about ten times more luminous than those in low-density environments. We show that the DF-superclusters that contain Abell clusters are richer and more luminous than the DF-superclusters without Abell clusters. The distribut...