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Spectrophotometry of galaxies in the Virgo cluster. II. The data
Drift-scan mode (3600-6800 Å) spectra with 500
| 1.65-μm (H -band) surface photometry of galaxies - VIII. The near-IR κ space at z =0
We present the distribution of a statistical sample of nearby galaxiesin the κ -space (κ 1 ~logM , κ 2~logI e 3 M /L , κ 3 ~logM /L ).Our study is based on near-IR (H -band: λ =1.65μm)observations, for the first time comprising early- and late-typesystems. Our data confirm that the mean effective dynamicalmass-to-light ratio M /L of the E+S0+S0a galaxies increases withincreasing effective dynamical mass M , as expected from the existenceof the Fundamental Plane relation. Conversely, spiral and Im/BCDgalaxies show a broad distribution in M /L with no detected trend of M/L with M , the former galaxies having M /L values about twice largerthan the latter, on average. For all the late-type galaxies, the M /Lincreases with decreasing effective surface intensity I e ,consistent with the existence of the Tully-Fisher relation. Theseresults are discussed on the basis of the assumptions behind theconstruction of the κ -space and their limitations. Our study iscomplementary to a previous investigation in the optical (B -band:λ =0.44μm) and allows us to study wavelength dependences ofthe galaxy distribution in the κ -space. As a first result, wefind that the galaxy distribution in the κ 1 -κ2 plane reproduces the transition from bulgeless tobulge-dominated systems in galaxies of increasing dynamical mass.Conversely, it appears that the M /L of late-types is higher (lower)than that of early-types with the same M in the near-IR (optical). Theorigins of this behaviour are discussed in terms of dust attenuation andstar formation history.
| 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.
| The Properties of Poor Groups of Galaxies. III. The Galaxy Luminosity Function
The form of the galaxy luminosity function (GLF) in poor groups-regionsof intermediate galaxy density that are common environments forgalaxies-is not well understood. Multiobject spectroscopy and wide-fieldCCD imaging now allow us to measure the GLF of bound group membersdirectly (i.e., without statistical background subtraction) and tocompare the group GLF with the GLFs of the field and of rich clusters.We use R-band images in 1.5×1.5 degree2 mosaics toobtain photometry for galaxies in the fields of six nearby(2800=MR>-19+5logh) to giants(MR<=-19+5logh) is significantly larger for the fivegroups with luminous X-ray halos than for the one marginallyX-ray-detected group; (2) the composite GLF for the luminous X-raygroups is consistent in shape with two measures of the composite R-bandGLF for rich clusters (Trentham; Driver et al.) and flatter at the faintend than another (α~-1.5 Smith et al.); (3) the composite groupGLF rises more steeply at the faint end than the R-band GLF of the LasCampanas Redshift Survey (LCRS; α=-0.7 from Lin et al.), a largevolume survey dominated by galaxies in environments more rarefied thanluminous X-ray groups; (4) the shape difference between the LCRS fieldand composite group GLFs results mostly from the population ofnon-emission line galaxies (EW [O II]<5 Å), whosedwarf-to-giant ratio is larger in the denser group environment than inthe field (cf. Ferguson & Sandage; Bromley et al.); and (5) thenon-emission line dwarfs are more concentrated about the group centerthan the non-emission line giants, except for the central, brightest(MR
| 1.65 ^mum (H-band) surface photometry of galaxies. IV. observations of 170 galaxies with the Calar Alto 2.2 m telescope
We present near-infrared (H band) surface photometry of 170 galaxies,obtained in 1997 using the Calar Alto 2.2 m telescope equipped with theNICMOS3 camera MAGIC. The majority of our targets are selected amongbright members of the Virgo cluster, however galaxies in the A262 andCancer clusters and in the Coma/A1367 supercluster are also included.This data set is aimed at complementing the NIR survey in the Virgocluster discussed in \cite[Boselli et al. (1997)]{B97} and in the ComaSupercluster, presented in Papers I, II and III of this series.Magnitudes at the optical radius, total magnitudes, isophotal radii andlight concentration indices are derivedTables 1 and 2 (full version) 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.Based on observations taken at the Calar Alto Observatory, operated bythe Max-Planck-Institut für Astronomie (Heidelberg) jointly withthe Spanish National Commission for Astronomy.
| 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
| Arcsecond Positions of UGC Galaxies
We present accurate B1950 and J2000 positions for all confirmed galaxiesin the Uppsala General Catalog (UGC). The positions were measuredvisually from Digitized Sky Survey images with rms uncertaintiesσ<=[(1.2")2+(θ/100)2]1/2,where θ is the major-axis diameter. We compared each galaxymeasured with the original UGC description to ensure high reliability.The full position list is available in the electronic version only.
| The I-Band Tully-Fisher Relation for SC Galaxies: Optical Imaging Data
Properties derived from the analysis of photometric I-band imagingobservations are presented for 1727 inclined spiral galaxies, mostly oftypes Sbc and Sc. The reduction, parameter extraction, and errorestimation procedures are discussed in detail. The asymptotic behaviorof the magnitude curve of growth and the radial variation in ellipticityand position angle are used in combination with the linearity of thesurface brightness falloff to fit the disk portion of the profile. TotalI-band magnitudes are calculated by extrapolating the detected surfacebrightness profile to a radius of eight disk scale lengths. Errors inthe magnitudes, typically ~0.04 mag, are dominated by uncertainties inthe sky subtraction and disk-fitting procedures. Comparison is made withthe similar imaging database of Mathewson, Ford, & Buchhorn, both aspresented originally by those authors and after reanalyzing theirdigital reduction files using identical disk-fitting procedures. Directcomparison is made of profile details for 292 galaxies observed incommon. Although some differences occur, good agreement is found,proving that the two data sets can be used in combination with onlyminor accommodation of those differences. The compilation of opticalproperties presented here is optimized for use in applications of theTully-Fisher relation as a secondary distance indicator in studies ofthe local peculiar velocity field.
| Galaxy coordinates. II. Accurate equatorial coordinates for 17298 galaxies
Using images of the Digitized Sky Survey we measured coodinates for17298 galaxies having poorly defined coordinates. As a control, wemeasured with the same method 1522 galaxies having accurate coordinates.The comparison with our own measurements shows that the accuracy of themethod is about 6 arcsec on each axis (RA and DEC).
| The Properties of Poor Groups of Galaxies. I. Spectroscopic Survey and Results
We use multifiber spectroscopy of 12 poor groups of galaxies to address(1) whether the groups are bound systems or chance projections ofgalaxies along the line of sight; (2) why the members of each group havenot already merged to form a single galaxy, despite the groups' highgalaxy densities, short crossing times, and likely environments forgalaxy-galaxy mergers; and (3) how galaxies might evolve in thesegroups, where the collisional effects of the intragroup gas and thetidal influences of the global potential are weaker than in richclusters. Each of the 12 groups has fewer than about five catalogedmembers in the literature. Our sample consists of 1002 galaxyvelocities, 280 of which are group members. The groups have meanrecessional velocities between 1600 and 7600 km s-1. Nine groups,including three Hickson compact groups, have the extended X-ray emissioncharacteristic of an intragroup medium (see Paper II). We conclude thefollowing: 1. The nine poor groups with diffuse X-ray emission are boundsystems with at least ~20-50 group members with absolute magnitudes asfaint as MB ~ -14 + 5 log10 h to -16 + 5 log10 h. The large number ofgroup members, the significant early-type population (up to ~55% of themembership) and its concentration in the group center, and thecorrespondence of the central, giant elliptical with the optical andX-ray group centroids argue that the X-ray groups are not radialsuperpositions of unbound galaxies. The velocity dispersions of theX-ray groups range from 190 to 460 km s-1. We are unable to determine ifthe three non-X-ray groups, which have lower velocity dispersions(<130 km s-1) and early-type fractions (=0%), are also bound. 2.Galaxies in each X-ray-detected group have not all merged togetherbecause a significant fraction of the group mass lies outside of thegalaxies and in a common halo. The velocity dispersion of the combinedgroup sample is constant as a function of radius out to the virialradius of the system (typically ~0.5 h-1 Mpc). The virial mass of eachgroup (~0.5-1 x 1014 h-1 Mȯ) is large compared with the mass in theX-ray gas and in the galaxies (e.g., ~1 x 1012 h-5/2 Mȯ and ~1 x1013 h-1 Mȯ, respectively, in NGC 533). These results imply thatmost of the group mass is in a common, extended halo. The small fraction(~10%-20%) of group mass associated with individual galaxies suggeststhat the rate of galaxy-galaxy interactions is lower than for agalaxy-dominated system, allowing these groups to virialize before allof their galaxies merge and to survive for more than a few crossingtimes. 3. The position of the giant, brightest elliptical in each X-raygroup is indistinguishable from the center of the group potential, asdefined by the mean velocity and the projected spatial centroid of thegroup galaxies. This result suggests that dominant cluster ellipticals,such as cD galaxies, may form via the merging of galaxies in the centersof poor group-like environments. Groups with a central, dominantelliptical may then fall into richer clusters. This scenario explainswhy cD galaxies do not always lie in the spatial and kinematic center ofrich clusters but instead occupy the centers of subclusters innonvirialized clusters. 4. The fraction of early-type galaxies in thepoor groups varies significantly, ranging from that characteristic ofthe field (<~25%) to that of rich clusters (~55%). The highearly-type fractions are particularly surprising because all of thegroups in this sample have substantially lower velocity dispersions (bya factor of ~2-5) and galaxy number densities (by a factor of ~5-20)than are typical of rich clusters. Hence, the effects of disruptivemechanisms like galaxy harassment on the morphology of poor groupgalaxies are weaker than in cluster environments. In contrast, thekinematics of poor groups make them preferred sites for galaxy-galaxymergers, which may alter the morphologies and star formation historiesof some group members. If galaxy-galaxy interactions are not responsiblefor the high early-type fractions, it is possible that the effects ofenvironment are relatively unimportant at the current epoch and that thesimilarity of the galaxy populations of rich clusters and some poorgroups reflects conditions at the time of galaxy formation. 5. Thefraction of early-type group members that have experienced starformation within the last ~2 h-1 Gyr is consistent with that in richclusters with significant substructure (~15%). If some of thesubclusters in these rich, complex clusters are groups that haverecently fallen into the cluster environment, the similarity between thestar formation histories of the early types in the subclusters and ofthose in our sample of field groups indicates that the clusterenvironment and associated mechanisms like ram pressure stripping arenot required to enhance and/or quench star formation in these particulargalaxies. If the recent star formation is tied to the externalenvironment of the galaxies and not to internal instabilities, it ismore likely that galaxy-galaxy encounters have altered the starformation histories of some early-type galaxies in groups and insubclusters.
| The Universality of the Fundamental Plane of E and S0 Galaxies: Spectroscopic Data
We present central velocity dispersion measurements for 325 early-typegalaxies in eight clusters and groups of galaxies, including newobservations for 212 galaxies. The clusters and groups are the A262,A1367, Coma (A1656), A2634, Cancer, and Pegasus Clusters and the NGC 383and NGC 507 Groups. The new measurements were derived frommedium-dispersion spectra that cover 600 Å centered on the Mg I btriplet at lambda ~ 5175 Å. Velocity dispersions were measuredusing the Tonry & Davis cross-correlation method, with a typicalaccuracy of 6%. A detailed comparison with other data sources is made.
| The Universality of the Fundamental Plane of E and S0 Galaxies: Sample Definition and I-Band Photometric Data
As part of a project to compare the fundamental plane and Tully-Fisherdistance scales, we present here I-band CCD photometry for 636early-type galaxies in eight clusters and groups of galaxies. These arethe A262, A1367, Coma (A1656), A2634, Cancer and Pegasus Clusters, andthe NGC 383 and NGC 507 Groups. Sample selection, cluster properties,and cluster membership assignment criteria are discussed. We presentphotometric parameters that are used in the fundamental plane relation,the effective radius r_e, and the effective surface brightness mu_e, asderived from a r^1/4 fit to the observed radial photometric profile ofeach galaxy. A comparison with similar data found in the literature forthe Coma Cluster shows that large systematic uncertainties can beintroduced in the measurement of r_e and mu_e by the particular methodused to derive those parameters. However, the particular combination ofthese two parameters that enters in the fundamental plane relation is aquantity that can be measured with high accuracy.
| Multifrequency windows on spiral galaxies. II - The A262 and Cancer clusters
New photometrical data (U,B,V and H bands) are presented for about 100spiral galaxies in the A262 and Cancer clusters. The data are used tostudy the dependence of radio continuum to H band and FIR to H bandratios on the color index U - B, taken as an indicator of the starformation history in galaxy disks. Both parameters are found to increasein bluer galaxies, in agreement with the results obtained for otherclusters or field galaxies. The radio continuum activity of spiralgalaxies in the Cancer cluster is not enhanced like in other clusterspirals. A study of the reliability of CCD surface photometry isreported, based on the comparison of two sets of observations obtainedwith different telescopes.
| Near infrared observations of galaxies in the Coma supercluster and in the Cancer cluster. II
New near infrared observations of 110 galaxies in the Coma/A1367supercluster region, and 40 galaxies in the Cancer cluster arepresented. These observations are part of an ongoing investigation ofthe properties of normal galaxies and of their near-IR emission, whichaims at obtaining homogeneous, multifrequency data for a large sample ofgalaxies in different density environments. The addition of theseobservations to the sample presented in Gavazzi and Trinchieri (1989)raises the number of Coma/A1367 galaxies with near-IR data to 275. Themeasurements, together with data published by Bothun et al. (1985), givea sample of 45 spirals in the Cancer cluster.
| Analysis of groups of galaxies with accurate redshifts
Arecibo radio telescope redshift measurements have been obtained forover 100 galaxies in more than 40 different groups which generallyconsist of a large spiral galaxy with one or more companions. This setof data is supplemented with over 160 galaxies in more than 40 groupswhose dominant galaxy is brighter than 11.8 mag. An analysis of theentire sample indicates that typical structure in extragalactic space isone in which a large central galaxy has smaller and fainter companionsextending from about 20-900 kpc around. The companion galaxies in thesegroups have significantly higher redshifts than the brightest galaxy inthe group, confirming previous studies in whose results the companiongalaxies are systematically redshifted with respect to the dominantgalaxy.
| The Cancer Cluster - an unbound collection of groups
A surface density contour map of the Cancer Cluster derived from galaxycounts in the Zwicky catalog is presented. The contour map shows thatthe galaxy distribution is clumpy. When this spatial distribution iscombined with nearly complete velocity information, the clumps stand outmore clearly; there are significant differences in the mean velocitiesof the clumps which exceed their internal velocity dispersions. TheCancer Cluster is not a proper 'cluster' but is a collection of discretegroups, each with a velocity dispersion of approximately 300 km/s,separating from one another with the cosmological flow. Themass-to-light ratio for galaxies in the main concentration isapproximately 320 solar masses/solar luminosities (H0 = 100km/s Mpc).
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