Study of the Structure of the Coma Cluster Based on a Hierarchical Powerful Clustering Method

Six subclusters in the Coma cluster have been selected on the basis of a hierarchical clustering method that takes the gravitational interaction among galaxies into account. Of these, three main subclusters around the galaxies NGC 4889, NGC 4874, and NGC 4839 have been singled out. We have used the objective statistical criterion applied by Vennik and Anosova in studies of close groups of galaxies to evaluate each member included in a subcluster with a high probability. Galaxies with a significant deficit of hydrogen HI, including objects from the Bravo-Alfaro list,have been identified with members of the subclusters, with the greatest number of them in the subclusters around NGC 4874 and NGC 4839. A quantitative estimate of the hydrogen deficit using the HI index in the RCG3 catalog reveals a statistically significant excess value for those galaxies that are members of the subclusters compared to the field galaxies with a hydrogen deficit in the studied area of Coma cluster. A substantial number of the spiral galaxies with a hydrogen deficit in the subclusters turned out to be radio galaxies as well.Comment: This is a revised version of the paper, published in "Astrophysics",vol.48, no 4, 200

Flattening of Galaxies of Different Morphological Types in Subclusters of Coma

The dependence of flattening of galaxies on the density of galaxies in subclusters selected around galaxies NGC4889, NGC4874 and NGC4839 in the Coma cluster has been studied. The mean values of observed ratios of galaxy diameters and histograms of their distributions indicate that in the central, dense regions of subclusters E and S0 type galaxies are close to spheroidals. Spiral galaxies in subcllusters are found with a hydrogen deficit that about 5 times exceeds the hydrogen deficit in spirals within the halo of the Coma cluster. Most of spirals with a hydrogen deficit in the subcluster around NGC 4874 according to their 3-D coordinates are located closer to the south-east edge of this subcluster near an extended gas filament in the x-ray region. This may indicate over the move of this subcluster toward the central condensation of faint galaxies in the Coma cluster for a possible merge with it.Comment: This material is a slightly corrected version of an article published in the "Astrophysics", Vol. 50, No. 3, 2007

The 2MASS Redshift Survey - Description and Data Release

We present the results of the 2MASS Redshift Survey (2MRS), a ten-year project to map the full three-dimensional distribution of galaxies in the nearby Universe. The 2 Micron All-Sky Survey (2MASS) was completed in 2003 and its final data products, including an extended source catalog (XSC), are available on-line. The 2MASS XSC contains nearly a million galaxies with Ks <= 13.5 mag and is essentially complete and mostly unaffected by interstellar extinction and stellar confusion down to a galactic latitude of |b|=5 deg for bright galaxies. Near-infrared wavelengths are sensitive to the old stellar populations that dominate galaxy masses, making 2MASS an excellent starting point to study the distribution of matter in the nearby Universe. We selected a sample of 44,599 2MASS galaxies with Ks =5 deg (>= 8 deg towards the Galactic bulge) as the input catalog for our survey. We obtained spectroscopic observations for 11,000 galaxies and used previously-obtained velocities for the remainder of the sample to generate a redshift catalog that is 97.6% complete to well-defined limits and covers 91% of the sky. This provides an unprecedented census of galaxy (baryonic mass) concentrations within 300 Mpc. Earlier versions of our survey have been used in a number of publications that have studied the bulk motion of the Local Group, mapped the density and peculiar velocity fields out to 50 Mpc, detected galaxy groups, and estimated the values of several cosmological parameters. Additionally, we present morphological types for a nearly-complete sub-sample of 20,860 galaxies with Ks = 10 deg.Comment: Accepted for publication in The Astrophysical Journal Supplement Series. The 2MRS catalogs and a version of the paper with higher-resolution figures can be found at http://tdc-www.harvard.edu/2mrs

Spectroscopic and photometric observations of galaxies from the ESO/Uppsala list - Third catalogue

Abstract image available at: http://esoads.eso.org/abs/1981A&AS...46...57

Spectroscopic and photometric observations of galaxies from the ESO/Uppsala list Second catalogue

Abstract image available at: http://esoads.eso.org/abs/1978A&AS...33..243