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Study of the Structure of the Coma Cluster Based on a Hierarchical Force Clustering Method
Six subclusters in the Coma cluster have been selected on the basis of ahierarchical clustering method that takes the gravitational interactionamong galaxies into account. Of these, 3 central subclusters around thegalaxies NGC 4889, NGC 4874, and NGC 4839 have been singled out. We haveused the objective statistical criterion applied by Vennik and Anosovain studies of close groups of galaxies to evaluate each member includedin a subcluster with a high probability. Galaxies with a significantdeficit of hydrogen HI, including objects from the Bravo-Alfaro list,have been identified with members of the subclusters, with the greatestnumber of them in the subclusters around NGC 4874 and NGC 4839. Aquantitative estimate of the hydrogen deficit using the HI index in theRCG3 catalog reveals a statistically significant excess value for thosegalaxies that are members of the subclusters compared to galaxies with ahydrogen deficit in the overall Coma cluster field. A substantial numberof the spiral galaxies with a hydrogen deficit in the subclusters turnedout to be radio galaxies as well.
| The UZC-SSRS2 Group Catalog
We apply a friends-of-friends algorithm to the combined Updated ZwickyCatalog and Southern Sky Redshift Survey to construct a catalog of 1168groups of galaxies; 411 of these groups have five or more members withinthe redshift survey. The group catalog covers 4.69 sr, and all groupsexceed the number density contrast threshold, δρ/ρ=80. Wedemonstrate that the groups catalog is homogeneous across the twounderlying redshift surveys; the catalog of groups and their membersthus provides a basis for other statistical studies of the large-scaledistribution of groups and their physical properties. The medianphysical properties of the groups are similar to those for groupsderived from independent surveys, including the ESO Key Programme andthe Las Campanas Redshift Survey. We include tables of groups and theirmembers.
| An Hα survey of eight Abell clusters: the dependence of tidally induced star formation on cluster density
We have undertaken a survey of Hα emission in a substantiallycomplete sample of CGCG galaxies of types Sa and later within 1.5 Abellradii of the centres of eight low-redshift Abell clusters (Abell 262,347, 400, 426, 569, 779, 1367 and 1656). Some 320 galaxies weresurveyed, of which 116 were detected in emission (39 per cent ofspirals, 75 per cent of peculiars). Here we present previouslyunpublished data for 243 galaxies in seven clusters. Detected emissionis classified as `compact' or `diffuse'. From an analysis of the fullsurvey sample, we confirm our previous identification of compact anddiffuse emission with circumnuclear starburst and disc emissionrespectively. The circumnuclear emission is associated either with thepresence of a bar, or with a disturbed galaxy morphology indicative ofongoing tidal interactions (whether galaxy-galaxy, galaxy-group, orgalaxy-cluster). The frequency of such tidally induced (circumnuclear)starburst emission in spirals increases from regions of lower to higherlocal galaxy surface density, and from clusters with lower to highercentral galaxy space density. The percentages of spirals classed asdisturbed and of galaxies classified as peculiar show a similar trend.These results suggest that tidal interactions for spirals are morefrequent in regions of higher local density and for clusters with highercentral galaxy density. The prevalence of such tidal interactions inclusters is expected from recent theoretical modelling of clusters witha non-static potential undergoing collapse and infall. Furthermore, inaccord with this picture, we suggest that peculiar galaxies arepredominantly ongoing mergers. We conclude that tidal interactions arelikely to be the main mechanism for the transformation of spirals to S0sin clusters. This mechanism operates more efficiently in higher densityenvironments, as is required by the morphological type-local surfacedensity (T-Σ) relation for galaxies in clusters. For regions ofcomparable local density, the frequency of tidally induced starburstemission is greater in clusters with higher central galaxy density. Thisimplies that, for a given local density, morphological transformation ofdisc galaxies proceeds more rapidly in clusters of higher central galaxydensity. This effect is considered to be the result of subclustermerging, and could account for the previously considered anomalousabsence of a significant T-Σ relation for irregular clusters atintermediate redshift.
| VLA H I Imaging of the Brightest Spiral Galaxies in Coma
We have obtained 21 cm images of 19 spiral galaxies in the Coma cluster,using the VLA in its C and D configurations. The sample selection wasbased on morphology, brightness, and optical diameters of galaxieswithin one Abell radius (1.2d). The H I-detected, yet deficient galaxiesshow a strong correlation in their H I properties with projecteddistance from the cluster center. The most strongly H I-deficient(DefH I>0.4) galaxies are located inside a radius of 30'(~0.6 Mpc) from the center of Coma, roughly the extent of the centralX-ray emission. These central galaxies show clear asymmetries in their HI distribution and/or shifts between the optical and 21 cm positions.Another 12 spirals were not detected in H I with typical H I mass upperlimits of 108 Msolar. Seven of the 12nondetections are located in the central region of Coma, roughly within30' from the center. The other nondetections are to the east andsouthwest of the center. We looked for seven so-called blue diskgalaxies in Coma in H I and detected six. These galaxies are relativelyclose to the central region of Coma. The nondetected one is the closestto the center. The six detected blue galaxies are mildly H I deficient.We did a more sensitive search for H I from 11 of the 15 knownpoststarburst galaxies in Coma. None were detected with typical H I masslimits between 3 and 7x107 Msolar. Our resultspresent and enhance a picture already familiar for well-studiedclusters. H I poor galaxies (deficient ones and nondetections) areconcentrated toward the center of the cluster. The H I morphology of thecentral galaxies with optical disks extending beyond the H I disks isunique to cluster environments and strongly suggests an interaction withthe intergalactic medium (IGM). A new result in Coma is the clumpydistribution of gas deficiency. In the cluster center the deficientgalaxies are to the east while the nondetections are to the west. In theouter parts the gas rich galaxies are north of Coma, nondetected spiralsare found in the NGC 4944 group to the east, and the NGC 4839 group isto the southwest. This supports recent findings that merging of groupsis ongoing in the center of Coma, farther out the NGC 4944 and NGC 4839must have passed at least once through the core, and the galaxies to thenorth have yet to fall in.
| 1.65 μm (H-band) surface photometry of galaxies. III. observations of 558 galaxies with the TIRGO 1.5 m telescope
We present near-infrared H-band (1.65 μm ) surface photometry of 558galaxies in the Coma Supercluster and in the Virgo cluster. This dataset, obtained with the Arcetri NICMOS3 camera ARNICA mounted on theGornergrat Infrared Telescope, is aimed at complementing, withobservations of mostly early-type objects, our NIR survey of spiralgalaxies in these regions, presented in previous papers of this series.Magnitudes at the optical radius, total magnitudes, isophotal radii andlight concentration indices are derived. We confirm the existence of apositive correlation between the near-infrared concentration index andthe galaxy H-band luminosity Based on observations taken at TIRGO(Gornergrat, Switzerland). TIRGO is operated by CAISMI-CNR, Arcetri,Firenze, Italy. Tables 1 and 2 are only available in electronic form atthe CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| 1.65 μm (H-band) surface photometry of galaxies. V. Profile decomposition of 1157 galaxies
We present near-infrared H-band (1.65 μm) surface brightness profiledecomposition for 1157 galaxies in five nearby clusters of galaxies:Coma, A1367, Virgo, A262 and Cancer, and in the bridge between Coma andA1367 in the ``Great Wall". The optically selected (mpg≤16.0) sample is representative of all Hubble types, from E to Irr+BCD,except dE and of significantly different environments, spanning fromisolated regions to rich clusters of galaxies. We model the surfacebrightness profiles with a de Vaucouleurs r1/4 law (dV), withan exponential disk law (E), or with a combination of the two (B+D).From the fitted quantities we derive the H band effective surfacebrightness (μe) and radius (re) of each component, theasymptotic magnitude HT and the light concentration indexC31. We find that: i) Less than 50% of the Ellipticalgalaxies have pure dV profiles. The majority of E to Sb galaxies is bestrepresented by a B+D profile. All Scd to BCD galaxies have pureexponential profiles. ii) The type of decomposition is a strong functionof the total H band luminosity (mass), independent of the Hubbleclassification: the fraction of pure exponential decompositionsdecreases with increasing luminosity, that of B+D increases withluminosity. Pure dV profiles are absent in the low luminosity rangeLH<1010 L\odot and become dominantabove 1011 L\odot . Based on observations taken atTIRGO, Gornergrat, Switzerland (operated by CAISMI-CNR, Arcetri,Firenze, Italy) and at the Calar Alto Observatory (operated by theMax-Planck-Institut für Astronomie (Heidelberg) jointly with theSpanish National Commission for Astronomy). Table 2 and Figs. 2, 3, 4are available in their entirety only in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| The distribution of the rotation axes of the disk galaxies in the Coma cluster: statistical samples.
Not Available
| The Butcher-Oemler Effect at Low Redshift: Spectroscopy of Five Nearby Clusters of Galaxies
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1997AJ....113..492C&db_key=AST
| Morphological classification and structural parameters of galaxies in the Coma and Perseus clusters
We present the results of an isophotal shape analysis of galaxies in theComa and Perseus clusters. These data, together with those of twoprevious papers, provide two complete samples of galaxies with reliableHubble types in rich clusters: 1) all galaxies brighter than m_b = 16.5falling within one degree (=2.3 Mpc) from the center of the Coma cluster(187 galaxies), 2) all galaxies brighter than m_Zwicky=15.7 in a regionof 5 degr 3' times 5 degr 27' around the center of the Perseus cluster(139 galaxies). These two complete samples cover 5 orders of magnitudein galaxy density and span areas of 91 and 17 Mpc^2, clustercentricradii up to 6.4 and 2.3 Mpc, for Perseus and Coma respectively. Theywill be used in subsequent papers to study the dependence of galaxytypes on cluster environment and as reference samples in comparisonswith distant clusters. Based on observations made with the 2-meterTelescope Bernard Lyot of Pic-du-Midi Observatory, operated by INSU(CNRS) and the Schmidt telescope at the Calern Observatory (OCA). Alltables are only available in electronic form at the CDS anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html.
| An image database. II. Catalogue between δ=-30deg and δ=70deg.
A preliminary list of 68.040 galaxies was built from extraction of35.841 digitized images of the Palomar Sky Survey (Paper I). For eachgalaxy, the basic parameters are obtained: coordinates, diameter, axisratio, total magnitude, position angle. On this preliminary list, weapply severe selection rules to get a catalog of 28.000 galaxies, wellidentified and well documented. For each parameter, a comparison is madewith standard measurements. The accuracy of the raw photometricparameters is quite good despite of the simplicity of the method.Without any local correction, the standard error on the total magnitudeis about 0.5 magnitude up to a total magnitude of B_T_=17. Significantsecondary effects are detected concerning the magnitudes: distance toplate center effect and air-mass effect.
| Automated surface photometry for the Coma Cluster galaxies: The catalog
A homogeneous photometry catalog is presented for 450 galaxies withB25.5 less than or equal to 16 mag located in the 9.8 deg x9.8 deg region centered on the Coma Cluster. The catalog is based onphotographic photometry using an automated surface photometry softwarefor data reduction applied to B-band Schmidt plates. The catalogprovides accurate positions, isophotal and total magnitudes, major andminor axes, and a few other photometric parameters including rudimentarymorphology (early of late type).
| Galaxy Properties at the North Galactic Pole. I. Photometric Properties on Large Spatial Scales
A two-color study of the galaxies detected on POSS-I in a 289 squaredegree region centered on the North Galactic Pole is presented. We use avariety of mapping techniques to characterize the large-scale spatialdistribution of galaxies. The depth and sample size of this new surveyallows, for the first time, the isolation of large photometricsubsamples of galaxies in high- and low-density environments on thescale of superclusters. Our principal finding is a statisticallysignificant difference between the mean photometric properties of thesesubsamples in the sense that galaxies in the high-density Coma andfilament environments have redder colors and larger concentrationindices than galaxies drawn from low-density interfilament regions.These results are in accord with the known morphology-density relation.Thus, appropriately chosen photometric and morphological parameters, inconcert with a galaxy surface density map, can be used to selectstructures from the projected galaxy distribution which correspond toregions of high density. An illustration of this point is our discoveryof a concentration of blue galaxies identified in our maps near the coreof the Coma cluster. This feature is comprised of early-type galaxieswhich exhibit signs of current or recent star formation. These resultsare predicated on relations between morphological type and photometricparameters derived from APS scans of POSS-I. We therefore discuss theimage calibration procedures used to compile our catalog of physicallysignificant photometric parameters. We demonstrate the morphologicaltype dependence among quantities such as mean color and imageconcentration index, and the lack of such a dependence for mean surfacebrightness.
| Radio-continuum survey of the Coma/A1367 supercluster. IV - 1.4 GHz observations of CGCG galaxies
1.4 GHz radio-continuum observations of 148 CGCG galaxies in the Comasupercluster region were obtained with the VLA in C array configuration.Comparison with previous measurements at 0.6 GHz leads to an averagespectral index of 0.8. The structures of 29 galaxies in this regiondetermined with high-resolution VLA (A array) observations arepresented.
| Cross identification of 238 galaxies and use of a colour magnitude relation in the coma cluster
A catalog of 238 galaxies is obtained by the cross identification ofdata from Kent and Gunn (1982), Godwin and Peach (1977) and Godwin etal. (1983). It contains the radial velocities, bvr magnitudes, colorindices, isophotal radii, and other characteristics of individualgalaxies. This leads to the definition of various samples of radialvelocities complete to various limiting magnitudes depending on radius.The use of a color magnitude relation is discussed to define a class of1340 objects likely to belong to the cluster from their photometry only.
| 21 centimeter study of spiral galaxies in the Coma supercluster
High-sensitivity, 21 cm line observations of 130 galaxies in theComa/A1367 Supercluster region are presented and used to study thelarge-scale distribution of galaxies in the direction of the ComaSupercluster and the H I content in spiral galaxies as a function of thelocal galaxy density. Groups of galaxies are found to form aquasi-continuous structure that connects the Local Supercluster to theComa Supercluster. This structure is composed of real filaments only inthe vicinity of the Coma Cluster. Spiral galaxies in the surveyed groupsand multiple systems have H I content not dissimilar from that ofisolated galaxies. Galaxies within about 1 Abell radius from the ComaCluster contain about three times less hydrogen on average than isolatedgalaxies. There is a strong tendency for galaxies that are more severelyH I-depleted to be redder and of earlier Hubble type. In the ComaCluster a considerable fraction of late-type, blue galaxies have largedeficiency parameters.
| The evolution of galaxies in clusters. IV - Photometry of 10 low-redshift clusters
Colors and magnitudes, obtained from Palomar 48 inch (1.2 m) Schmidtplates in the J and F bands, and morphological types are presented forgalaxies in the cores of 10 nearby clusters of galaxies. In the typicalcluster, the sample includes all galaxies within a radius of 1.5 Mpc(assuming H(0) = 50 km/s/Mpc) of the cluster center and brighter than J= 17.5.The accuracy of the photometry varies with cluster, but mostmagnitudes are accurate to 0.10 mag, and typical errors in the colorsare of the same order. As expected, the colors of the elliptical and S0galaxies show a narrow dispersion about a mean color which decreaseswith magnitude. However, the colors of the spiral galaxies are notentirely as expected, having a smaller dispersion than would have beenpredicted from their morphological types.
| A catalog of radio, optical, and infrared observations of spiral galaxies in clusters
The results of a major observational program on the luminosities,colors, and gas contents of spiral galaxies in clusters of galaxies arepresented. The data have been used as part of a detailed investigationinto the nature of cluster spirals and for revisions of the distancescale using the infrared Tully-Fisher relation. The observationalstrategies, reduction procedures, and sources or error are brieflydiscussed. The data include 21-cm H I observations, UBVR multiaperturephotometry, and H-band photometry of several hunderd spiral galaxies in10 clusters.
| The Coma Cluster - Part One - a Catalogue of Magnitudes Colours Ellipticities and Position Angles for 6724 Galaxies in the Field of the Coma Cluster
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1983MNRAS.202..113G&db_key=AST
| The dynamics of rich clusters of galaxies. I - The Coma cluster
Self-consistent analytical dynamical models are used to study theendpoint of cluster formation, concentrating on the Coma cluster.Particular attention is paid to the effects of anisotropy in thevelocity dispersion and variations in the energy-distribution functionon the cluster structure, the effect on the core structure of a massivecentral object, the dynamical consequences of morphological segregation,cosmological infall and the edge of a cluster, the distribution of darkmatter in a cluster, and the implications of X-ray observations for thedistribution of gravitating material in a cluster. Radial velocity datais displayed, and new and repeated redshifts are reported for a numberof galaxies in the central regions of the cluster. Cluster membership isdetermined and a velocity-dispersion profile is derived. A compositesurface-density profile is derived, and amazing examples are shown ofmodels with virtually identical surface-density profiles but otherwisecompletely different internal dynamics.
| A catalog of morphological types in 55 rich clusters of galaxies
Data are presented from a study of 55 rich clusters of galaxies. Thedata include positions, morphological types, estimated total magnitudes,bulge sizes, and ellipticities for about 6000 galaxies, as determinedfrom high scale photographic plates. Data reduction procedures aredescribed, and a brief analysis of cluster richness, which indicatesthat Abell richness classes are only rough indicators of total clustermembership, is included.
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