SDSS superclusters: morphology and galaxy content

We compare the galaxy populations in superclusters of different morphology in the nearby Universe (180 < d < 270 Mpc) to see whether the inner structure and overall morphology of superclusters are important in shaping galaxy properties in superclusters. Supercluster morphology has been found with Minkowski functionals. We analyse the probability density distributions of colours, morphological types, stellar masses, star formation rates (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 show that the fraction of red, early-type, low SFR galaxies in filament-type superclusters is higher than in spider-type superclusters; in low-density global environments their fraction is lower than in superclusters. In all environments the fraction of red, high stellar mass, and low SFR galaxies in rich groups is higher than in poor groups. In superclusters of spider morphology red, high SFR galaxies have higher stellar masses than in filament-type superclusters. Groups of equal richness host galaxies with larger stellar masses, a larger fraction of early-type and red galaxies, and a higher fraction of low SFR galaxies, if they are located in superclusters of filament morphology. The peculiar velocities of the main galaxies in groups from superclusters of filament morphology are higher than in those of spider morphology. Groups with higher peculiar velocities of their main galaxies in filament-type superclusters are located in higher density environment than those with low peculiar velocities. There are significant differences between galaxy populations of the individual richest superclusters. Therefore both local (group) and global (supercluster) environments and even supercluster morphology play an important role in the formation and evolution of galaxies.Comment: Comments: 14 pages, 11 figures, accepted for publication in Astronomy and Astrophysic

Discovery of a massive supercluster system at z∼0.47z \sim 0.47

Superclusters are the largest relatively isolated systems in the cosmic web. Using the SDSS BOSS survey we search for the largest superclusters in the redshift range $0.43<z<0.71$. We generate a luminosity-density field smoothed over $8 h^{-1}\mathrm{Mpc}$ to detect the large-scale over-density regions. Each individual over-density region is defined as single supercluster in the survey. We define the superclusters in the way that they are comparable with the superclusters found in the SDSS main survey. We found a system we call the BOSS Great Wall (BGW), which consists of two walls with diameters 186 and 173 $h^{-1}$Mpc, and two other major superclusters with diameters of 64 and 91 $h^{-1}$Mpc. As a whole, this system consists of 830 galaxies with the mean redshift 0.47. We estimate the total mass to be approximately $2\times10^{17}h^{-1}M_\odot$. The morphology of the superclusters in the BGW system is similar to the morphology of the superclusters in the Sloan Great Wall region. The BGW is one of the most extended and massive system of superclusters yet found in the Universe.Comment: 4 pages, accepted as a letter in A&

Environments of galaxies in groups within the supercluster-void network

Conclusions. Our results suggest that the evolution of galaxies is affected by both, the group in which the galaxy resides and its large-scale environment. Galaxies in lower-density regions develop later than galaxies in similar mass groups in high-density environmen

Large-scale environments of narrow-line Seyfert 1 galaxies

Studying large-scale environments of narrow-line Seyfert 1 (NLS1) galaxies gives a new perspective on their properties, particularly their radio loudness. The large-scale environment is believed to have an impact on the evolution and intrinsic properties of galaxies, however, NLS1 sources have not been studied in this context before. We have a large and diverse sample of 1341 NLS1 galaxies and three separate environment data sets constructed using Sloan Digital Sky Survey. We use various statistical methods to investigate how the properties of NLS1 galaxies are connected to the large-scale environment, and compare the large-scale environments of NLS1 galaxies with other active galactic nuclei (AGN) classes, for example, other jetted AGN and broad-line Seyfert 1 (BLS1) galaxies, to study how they are related. NLS1 galaxies reside in less dense environments than any of the comparison samples, thus confirming their young age. The average large-scale environment density and environmental distribution of NLS1 sources is clearly different compared to BLS1 galaxies, thus it is improbable that they could be the parent population of NLS1 galaxies and unified by orientation. Within the NLS1 class there is a trend of increasing radio loudness with increasing large-scale environment density, indicating that the large-scale environment affects their intrinsic properties. Our results suggest that the NLS1 class of sources is not homogeneous, and furthermore, that a considerable fraction of them are misclassified. We further support a published proposal to replace the traditional classification to radio-loud, and radio-quiet or radio-silent sources with a division into jetted and non-jetted sources

Multifrequency studies of galaxies and groups I. Environmental effect on galaxy stellar mass and morphology

Context. To understand the role of the environment in galaxy formation, evolution, and present-day properties, it is essential to study the multifrequency behavior of different galaxy populations under various environmental conditions.Aims. We study the stellar mass functions of different galaxy populations in groups as a function of their large-scale environments using multifrequency observations.Methods. We cross-matched the SDSS DR10 group catalog with GAMA Data Release 2 and Wide-field Survey Explorer (WISE) data to construct a catalog of 1651 groups and 11 436 galaxies containing photometric information in 15 different wavebands ranging from ultraviolet (0.152 mu m) to mid-infrared (22 mu m). We performed the spectral energy distribution (SED) fitting of galaxies using the MAGPHYS code and estimate the rest-frame luminosities and stellar masses. We used the 1/V-max method to estimate the galaxy stellar mass and luminosity functions, and the luminosity density field of galaxies to define the large-scale environment of galaxies.Results. The stellar mass functions of both central and satellite galaxies in groups are different in low-and high-density, large-scale environments. Satellite galaxies in high-density environments have a steeper low-mass end slope compared to low-density environments, independent of the galaxy morphology. Central galaxies in low-density environments have a steeper low-mass end slope, but the difference disappears for fixed galaxy morphology. The characteristic stellar mass of satellite galaxies is higher in high-density environments and the difference exists only for galaxies with elliptical morphologies.Conclusions. Galaxy formation in groups is more efficient in high-density, large-scale environments. Groups in high-density environments have higher abundances of satellite galaxies, irrespective of the satellite galaxy morphology. The elliptical satellite galaxies are generally more massive in high-density environments. The stellar masses of spiral satellite galaxies show no dependence on the large-scale environment

Environments of galaxies in groups within the supercluster-void network

Majority of all galaxies reside in groups of less than 50 member galaxies. These groups are distributed in various large-scale environments from voids to superclusters. Evolution of galaxies is affected by the environment in which they reside. Our aim is to study the effects that the local group scale and the supercluster scale environment have on galaxies. We use a luminosity-density field to determine density of the large-scale environment of galaxies in groups of various richness. We calculate fractions of different types of galaxies in groups with richnesses up to 50 member galaxies and in different large-scale environments from voids to superclusters. 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 the large scale, the passive elliptical galaxies become more numerous than star-forming spirals when the environmental density grows to the density level typical for 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 in lower densities. The crossing point, where the number of passive and star-forming galaxies is equal, happens in groups with lower richness in superclusters than in voids. Galaxies in low-density areas require richer groups to evolve from star-forming to passive. Groups in superclusters are on average more luminous than groups in large-scale environments with lower density. Our results suggest that the evolution of galaxies is affected by both, by the group in which the galaxy resides, and by its large-scale environment. Galaxies in lower-density regions develop later than galaxies in similar mass groups in high-density environments.Comment: 10 pages, 9 figures. Published in A&A. Language corrected 9th Oct 201

Appendicolith appendicitis is clinically complicated acute appendicitis – is it histopathologically different from uncomplicated acute appendicitis

Purpose: Acute appendicitis may present as uncomplicated and complicated and these disease forms differ both epidemiologically and clinically. Complicated acute appendicitis has traditionally been defined as an appendicitis complicated by perforation or a periappendicular abscess, and an appendicolith represents a predisposing factor of complicated disease. There are histopathological differences between uncomplicated acute appendicitis and the previously established traditional forms of complicated acute appendicitis, but to our knowledge, the histopathological differences between uncomplicated acute appendicitis and complicated acute appendicitis presenting with an appendicolith have not yet been reported. The study purpose was to assess these differences with two prospective patient cohorts: (1) computed tomography (CT) confirmed uncomplicated acute appendicitis patients enrolled in the surgical treatment arm of the randomized APPAC trial comparing appendectomy with antibiotics for the treatment of uncomplicated acute appendicitis and (2) patients with CT-verified acute appendicitis presenting with an appendicolith excluded from the APPAC trial.Methods: The following histopathological parameters were assessed: appendiceal diameter, depth of inflammation, micro-abscesses, density of eosinophils, and neutrophils in appendiceal wall and surface epithelium degeneration.Results: Using multivariable logistic regression models adjusted for age, gender, and symptom duration, statistically significant differences were detected in the depth of inflammation = 150/mm(2) (adjusted OR 0.97 (95%CI: 0.95-0.99, p=0.013), adjusted OR 3.04 (95%CI: 1.82-5.09, pConclusions: These results corroborate the known clinical association of an appendicolith to complicated acute appendicitis.</div

Sloan Great Wall as a complex of superclusters with collapsing cores

Context. The formation and evolution of the cosmic web is governed by the gravitational attraction of dark matter and antigravity of dark energy (cosmological constant). In the cosmic web, galaxy superclusters or their high-density cores are the largest objects that may collapse at present or during the future evolution.Aims. We study the dynamical state and possible future evolution of galaxy superclusters from the Sloan Great Wall (SGW), the richest galaxy system in the nearby Universe.Methods. We calculated supercluster masses using dynamical masses of galaxy groups and stellar masses of galaxies. We employed normal mixture modelling to study the structure of rich SGW superclusters and search for components (cores) in superclusters. We analysed the radial mass distribution in the high-density cores of superclusters centred approximately at rich clusters and used the spherical collapse model to study their dynamical state.Results. The lower limit of the total mass of the SGW is approximately M = 2.5 x 10(16) h(-1) M-circle dot. Different mass estimators of superclusters agree well, the main uncertainties in masses of superclusters come from missing groups and clusters. We detected three high-density cores in the richest SGW supercluster (SCl 027) and two in the second richest supercluster (SCl 019). They have masses of 1.2-5.9 x 10(15) h(-1) M-circle dot and sizes of up to approximate to 60 h(-1) Mpc. The high-density cores of superclusters are very elongated, flattened perpendicularly to the line of sight. The comparison of the radial mass distribution in the high-density cores with the predictions of spherical collapse model suggests that their central regions with radii smaller than 8 h(-1) Mpc and masses of up to M = 2 x 10(15) h(-1) M-circle dot may be collapsing.Conclusions. The rich SGW superclusters with their high-density cores represent dynamically evolving environments for studies of the properties of galaxies and galaxy systems

A structure in the early Universe at z 1.3 that exceeds the homogeneity scale of the R-W concordance cosmology

A Large Quasar Group (LQG) of particularly large size and high membership has been identified in the DR7QSO catalogue of the Sloan Digital Sky Survey. It has characteristic size (volume^1/3) ~ 500 Mpc (proper size, present epoch), longest dimension ~ 1240 Mpc, membership of 73 quasars, and mean redshift = 1.27. In terms of both size and membership it is the most extreme LQG found in the DR7QSO catalogue for the redshift range 1.0 = 1.28, which is itself one of the more extreme examples. Their boundaries approach to within ~ 2 deg (~ 140 Mpc projected). This new, huge LQG appears to be the largest structure currently known in the early universe. Its size suggests incompatibility with the Yadav et al. scale of homogeneity for the concordance cosmology, and thus challenges the assumption of the cosmological principle