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The ACS Virgo Cluster Survey. VIII. The Nuclei of Early-Type Galaxies
The ACS Virgo Cluster Survey is a Hubble Space Telescope program toobtain high-resolution imaging in widely separated bandpasses (F475W~gand F850LP~z) for 100 early-type members of the Virgo Cluster, spanninga range of ~460 in blue luminosity. We use this large, homogenous dataset to examine the innermost structure of these galaxies and tocharacterize the properties of their compact central nuclei. We presenta sharp upward revision in the frequency of nucleation in early-typegalaxies brighter than MB~-15 (66%<~fn<~82%)and show that ground-based surveys underestimated the number of nucleidue to surface brightness selection effects, limited sensitivity andpoor spatial resolution. We speculate that previously reported claimsthat nucleated dwarfs are more concentrated toward the center of Virgothan their nonnucleated counterparts may be an artifact of theseselection effects. There is no clear evidence from the properties of thenuclei, or from the overall incidence of nucleation, for a change atMB~-17.6, the traditional dividing point between dwarf andgiant galaxies. There does, however, appear to be a fundamentaltransition at MB~-20.5, in the sense that the brighter,``core-Sérsic'' galaxies lack resolved (stellar) nuclei. A searchfor nuclei that may be offset from the photocenters of their hostgalaxies reveals only five candidates with displacements of more than0.5", all of which are in dwarf galaxies. In each case, however, theevidence suggests that these ``nuclei'' are, in fact, globular clustersprojected close to the galaxy photocenter. Working from a sample of 51galaxies with prominent nuclei, we find a median half-light radius of=4.2 pc, with the sizes of individual nucleiranging from 62 pc down to <=2 pc (i.e., unresolved in our images) inabout a half-dozen cases. Excluding these unresolved objects, the nucleisizes are found to depend on nuclear luminosity according to therelation rh L0.50+/-0.03. Because the largemajority of nuclei are resolved, we can rule out low-level AGNs as anexplanation for the central luminosity excess in almost all cases. Onaverage, the nuclei are ~3.5 mag brighter than a typical globularcluster. Based on their broadband colors, the nuclei appear to have oldto intermediate age stellar populations. The colors of the nuclei ingalaxies fainter than MB~-17.6 are tightly correlated withtheir luminosities, and less so with the luminosities of their hostgalaxies, suggesting that their chemical enrichment histories weregoverned by local or internal factors. Comparing the nuclei to the``nuclear clusters'' found in late-type spiral galaxies reveals a closematch in terms of size, luminosity, and overall frequency. A formationmechanism that is rather insensitive to the detailed properties of thehost galaxy properties is required to explain this ubiquity andhomogeneity. The mean of the frequency function for thenucleus-to-galaxy luminosity ratio in our nucleated galaxies,=-2.49+/-0.09 dex (σ=0.59+/-0.10), isindistinguishable from that of the SBH-to-bulge mass ratio,=-2.61+/-0.07dex (σ=0.45+/-0.09), calculated in 23 early-type galaxies withdetected supermassive black holes (SBHs). We argue that the compactstellar nuclei found in many of our program galaxies are the low-masscounterparts of the SBHs detected in the bright galaxies. If thisinterpretation is correct, then one should think in terms of ``centralmassive objects''-either SBHs or compact stellar nuclei-that accompanythe formation of almost all early-type galaxies and contain a meanfraction ~0.3% of the total bulge mass. In this view, SBHs would be thedominant formation mode above MB~-20.5.Based on observations with the NASA/ESA Hubble Space Telescope obtainedat the Space Telescope Science Institute, which is operated by theAssociation of Universities for Research in Astronomy, Inc., under NASAcontract NAS5-26555.
| The ACS Virgo Cluster Survey. IX. The Color Distributions of Globular Cluster Systems in Early-Type Galaxies
We present the color distributions of globular cluster (GC) systems for100 early-type galaxies observed in the ACS Virgo Cluster Survey, thedeepest and most homogeneous survey of this kind to date. On average,galaxies at all luminosities in our study (-22
| The ACS Virgo Cluster Survey. X. Half-Light Radii of Globular Clusters in Early-Type Galaxies: Environmental Dependencies and a Standard Ruler for Distance Estimation
We have measured half-light radii, rh, for thousands ofglobular clusters (GCs) belonging to the 100 early-type galaxiesobserved in the ACS Virgo Cluster Survey and the elliptical galaxy NGC4697. An analysis of the dependencies of the measured half-light radiion both the properties of the GCs themselves and their host galaxiesreveals that, in analogy with GCs in the Galaxy but in a milder fashion,the average half-light radius increases with increasing galactocentricdistance or, alternatively, with decreasing galaxy surface brightness.For the first time, we find that the average half-light radius decreaseswith the host galaxy color. We also show that there is no evidence for avariation of rh with the luminosity of the GCs. Finally, wefind in agreement with previous observations that the averagerh depends on the color of GCs, with red GCs being ~17%smaller than their blue counterparts. We show that this difference isprobably a consequence of an intrinsic mechanism, rather than projectioneffects, and that it is in good agreement with the mechanism proposed byJordán. We discuss these findings in light of two simple picturesfor the origin of the rh of GCs and show that both lead to abehavior in rough agreement with the observations. After accounting forthe dependencies on galaxy color, galactocentric radius, and underlyingsurface brightness, we show that the average GC half-light radii can be successfully used as a standard ruler fordistance estimation. We outline the methodology, provide a calibrationfor its use, and discuss the prospects for this distance estimator withfuture observing facilities. We find =2.7+/-0.35 pcfor GCs with (g-z)=1.2 mag in a galaxy with color(g-z)gal=1.5 mag and at an underlying surface z-bandbrightness of μz=21 mag arcsec-2. Using thistechnique, we place an upper limit of 3.4 Mpc on the 1 σline-of-sight depth of the Virgo Cluster. Finally, we examine the formof the rh distribution for our sample galaxies and provide ananalytic expression that successfully describes this distribution.Based on observations with the NASA/ESA Hubble Space Telescope obtainedat the Space Telescope Science Institute, which is operated by theAssociation of Universities for Research in Astronomy, Inc., under NASAcontract NAS 5-26555.
| The ACS Virgo Cluster Survey. II. Data Reduction Procedures
The ACS Virgo Cluster Survey is a large program to carry out multicolorimaging of 100 early-type members of the Virgo Cluster using theAdvanced Camera for Surveys (ACS) on the Hubble Space Telescope. DeepF475W and F850LP images (~SDSS g and z) are being used to study thecentral regions of the program galaxies, their globular cluster systems,and the three-dimensional structure of Virgo itself. In this paper, wedescribe in detail the data reduction procedures used for the survey,including image registration, drizzling strategies, the computation ofweight images, object detection, the identification of globular clustercandidates, and the measurement of their photometric and structuralparameters.Based on observations with the NASA/ESA Hubble Space Telescope obtainedat the Space Telescope Science Institute, which is operated by theAssociation of Universities for Research in Astronomy, Inc., under NASAcontract NAS 5-26555.
| The ACS Virgo Cluster Survey. I. Introduction to the Survey
The Virgo Cluster is the dominant mass concentration in the LocalSupercluster and the largest collection of elliptical and lenticulargalaxies in the nearby universe. In this paper, we present anintroduction to the ACS Virgo Cluster Survey: a program to image, in theF475W and F850LP bandpasses (~Sloan g and z), 100 early-type galaxies inthe Virgo Cluster using the Advanced Camera for Surveys on the HubbleSpace Telescope. We describe the selection of the program galaxies andtheir ensemble properties, the choice of filters, the field placementand orientation, the limiting magnitudes of the survey, coordinatedparallel observations of 100 ``intergalactic'' fields with WFPC2, andsupporting ground-based spectroscopic observations of the programgalaxies. In terms of depth, spatial resolution, sample size, andhomogeneity, this represents the most comprehensive imaging survey todate of early-type galaxies in a cluster environment. We brieflydescribe the main scientific goals of the survey, which include themeasurement of luminosities, metallicities, ages, and structuralparameters for the many thousands of globular clusters associated withthese galaxies, a high-resolution isophotal analysis of galaxiesspanning a factor of ~450 in luminosity and sharing a commonenvironment, the measurement of accurate distances for the full sampleof galaxies using the method of surface brightness fluctuations, and adetermination of the three-dimensional structure of Virgo itself.ID="FN1"> 1Based on observations with the NASA/ESA Hubble SpaceTelescope obtained at the Space Telescope Science Institute, which isoperated by the association of Universities for Research in Astronomy,Inc., under NASA contract NAS 5-26555.
| Properties of isolated disk galaxies
We present a new sample of northern isolated galaxies, which are definedby the physical criterion that they were not affected by other galaxiesin their evolution during the last few Gyr. To find them we used thelogarithmic ratio, f, between inner and tidal forces acting upon thecandidate galaxy by a possible perturber. The analysis of thedistribution of the f-values for the galaxies in the Coma cluster leadus to adopt the criterion f ≤ -4.5 for isolated galaxies. Thecandidates were chosen from the CfA catalog of galaxies within thevolume defined by cz ≤5000 km s-1, galactic latitudehigher than 40o and declination ≥-2.5o. Theselection of the sample, based on redshift values (when available),magnitudes and sizes of the candidate galaxies and possible perturberspresent in the same field is discussed. The final list of selectedisolated galaxies includes 203 objects from the initial 1706. The listcontains only truly isolated galaxies in the sense defined, but it is byno means complete, since all the galaxies with possible companions underthe f-criterion but with unknown redshift were discarded. We alsoselected a sample of perturbed galaxies comprised of all the diskgalaxies from the initial list with companions (with known redshift)satisfying f ≥ -2 and \Delta(cz) ≤500 km s-1; a totalof 130 objects. The statistical comparison of both samples showssignificant differences in morphology, sizes, masses, luminosities andcolor indices. Confirming previous results, we found that late spiral,Sc-type galaxies are, in particular, more frequent among isolatedgalaxies, whereas Lenticular galaxies are more abundant among perturbedgalaxies. Isolated systems appear to be smaller, less luminous and bluerthan interacting objects. We also found that bars are twice as frequentamong perturbed galaxies compared to isolated galaxies, in particularfor early Spirals and Lenticulars. The perturbed galaxies have higherLFIR/LB and Mmol/LB ratios,but the atomic gas content is similar for the two samples. The analysisof the luminosity-size and mass-luminosity relations shows similartrends for both families, the main difference being the almost totalabsence of big, bright and massive galaxies among the family of isolatedsystems, together with the almost total absence of small, faint and lowmass galaxies among the perturbed systems. All these aspects indicatethat the evolution induced by interactions with neighbors would proceedfrom late, small, faint and low mass Spirals to earlier, bigger, moreluminous and more massive spiral and lenticular galaxies, producing atthe same time a larger fraction of barred galaxies but preserving thesame relations between global parameters. The properties we found forour sample of isolated galaxies appear similar to those of high redshiftgalaxies, suggesting that the present-day isolated galaxies could bequietly evolved, unused building blocks surviving in low densityenvironments.Tables \ref{t1} and \ref{t2} are only available in electronic form athttp://www.edpsciences.org
| Redshift-Distance Survey of Early-Type Galaxies: Spectroscopic Data
We present central velocity dispersions and Mg2 line indicesfor an all-sky sample of ~1178 elliptical and S0 galaxies, of which 984had no previous measures. This sample contains the largest set ofhomogeneous spectroscopic data for a uniform sample of ellipticalgalaxies in the nearby universe. These galaxies were observed as part ofthe ENEAR project, designed to study the peculiar motions and internalproperties of the local early-type galaxies. Using 523 repeatedobservations of 317 galaxies obtained during different runs, the dataare brought to a common zero point. These multiple observations, takenduring the many runs and different instrumental setups employed for thisproject, are used to derive statistical corrections to the data and arefound to be relatively small, typically <~5% of the velocitydispersion and 0.01 mag in the Mg2 line strength. Typicalerrors are about 8% in velocity dispersion and 0.01 mag inMg2, in good agreement with values published elsewhere.
| Star Formation Histories of Early-Type Galaxies. I. Higher Order Balmer Lines as Age Indicators
We have obtained blue integrated spectra of 175 nearby early-typegalaxies, covering a wide range in galaxy velocity dispersion andemphasizing those with σ<100 km s-1. Galaxies havebeen observed both in the Virgo Cluster and in lower densityenvironments. The main goals are the evaluation of higher order Balmerlines as age indicators and differences in stellar populations as afunction of mass, environment, and morphology. In this first paper, ouremphasis is on presenting the methods used to characterize the behaviorof the Balmer lines through evolutionary population synthesis models.Lower σ galaxies exhibit a substantially greater intrinsicscatter, in a variety of line-strength indicators, than do higherσ galaxies, with the large intrinsic scatter setting in below aσ of 100 km s-1. Moreover, a greater contrast inscatter is present in the Balmer lines than in the lines of metalfeatures. Evolutionary synthesis modeling of the observed spectralindexes indicates that the strong Balmer lines found primarily among thelow-σ galaxies are caused by young age, rather than by lowmetallicity. Thus we find a trend between the population age and thecentral velocity dispersion, such that low-σ galaxies have youngerluminosity-weighted mean ages. We have repeated this analysis usingseveral different Balmer lines and find consistent results from onespectral indicator to another.
| Redshift-Distance Survey of Early-Type Galaxies: Circular-Aperture Photometry
We present R-band CCD photometry for 1332 early-type galaxies, observedas part of the ENEAR survey of peculiar motions using early-typegalaxies in the nearby universe. Circular apertures are used to tracethe surface brightness profiles, which are then fitted by atwo-component bulge-disk model. From the fits, we obtain the structuralparameters required to estimate galaxy distances using theDn-σ and fundamental plane relations. We find thatabout 12% of the galaxies are well represented by a pure r1/4law, while 87% are best fitted by a two-component model. There are 356repeated observations of 257 galaxies obtained during different runsthat are used to derive statistical corrections and bring the data to acommon system. We also use these repeated observations to estimate ourinternal errors. The accuracy of our measurements are tested by thecomparison of 354 galaxies in common with other authors. Typical errorsin our measurements are 0.011 dex for logDn, 0.064 dex forlogre, 0.086 mag arcsec-2 for<μe>, and 0.09 for mRC,comparable to those estimated by other authors. The photometric datareported here represent one of the largest high-quality and uniformall-sky samples currently available for early-type galaxies in thenearby universe, especially suitable for peculiar motion studies.Based on observations at Cerro Tololo Inter-American Observatory (CTIO),National Optical Astronomy Observatory, which is operated by theAssociation of Universities for Research in Astronomy, Inc., undercooperative agreement with the National Science Foundation (NSF);European Southern Observatory (ESO); Fred Lawrence Whipple Observatory(FLWO); and the MDM Observatory on Kitt Peak.
| A new catalogue of ISM content of normal galaxies
We have compiled a catalogue of the gas content for a sample of 1916galaxies, considered to be a fair representation of ``normality''. Thedefinition of a ``normal'' galaxy adopted in this work implies that wehave purposely excluded from the catalogue galaxies having distortedmorphology (such as interaction bridges, tails or lopsidedness) and/orany signature of peculiar kinematics (such as polar rings,counterrotating disks or other decoupled components). In contrast, wehave included systems hosting active galactic nuclei (AGN) in thecatalogue. This catalogue revises previous compendia on the ISM contentof galaxies published by \citet{bregman} and \citet{casoli}, andcompiles data available in the literature from several small samples ofgalaxies. Masses for warm dust, atomic and molecular gas, as well asX-ray luminosities have been converted to a uniform distance scale takenfrom the Catalogue of Principal Galaxies (PGC). We have used twodifferent normalization factors to explore the variation of the gascontent along the Hubble sequence: the blue luminosity (LB)and the square of linear diameter (D225). Ourcatalogue significantly improves the statistics of previous referencecatalogues and can be used in future studies to define a template ISMcontent for ``normal'' galaxies along the Hubble sequence. The cataloguecan be accessed on-line and is also available at the Centre desDonnées Stellaires (CDS).The catalogue is available in electronic form athttp://dipastro.pd.astro.it/galletta/ismcat and at the CDS via anonymousftp to\ cdsarc.u-strasbg.fr (130.79.128.5) or via\http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/405/5
| 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.
| Redshift-Distance Survey of Early-Type Galaxies. I. The ENEARc Cluster Sample
This paper presents data on the ENEARc subsample of the larger ENEARsurvey of nearby early-type galaxies. The ENEARc galaxies belong toclusters and were specifically chosen to be used for the construction ofa Dn-σ template. The ENEARc sample includes newmeasurements of spectroscopic and photometric parameters (redshift,velocity dispersion, line index Mg2, and the angular diameterdn), as well as data from the literature. New spectroscopicdata are given for 229 cluster early-type galaxies, and new photometryis presented for 348 objects. Repeat and overlap observations withexternal data sets are used to construct a final merged catalogconsisting of 640 early-type galaxies in 28 clusters. Objectivecriteria, based on catalogs of groups of galaxies derived from completeredshift surveys of the nearby universe, are used to assign galaxies toclusters. In a companion paper, these data are used to construct thetemplate Dn-σ distance relation for early-typegalaxies, which has been used to estimate galaxy distances and derivepeculiar velocities for the ENEAR all-sky sample. Based on observationsat Complejo Astronomico El Leoncito, operated under agreement betweenthe Consejo Nacional de Investigaciones Científicas de laRepública Argentina and the National Universities of La Plata,Córdoba, and San Juan; Cerro Tololo Inter-American Observatory,National Optical Astronomical Observatory, which is operated by theAssociation of Universities for Research in Astronomy, Inc., undercooperative agreement with the National Science Foundation; the EuropeanSouthern Observatory (ESO), partially under the ESO-ON agreement; theFred Lawrence Whipple Observatory; the Observatório do Pico dosDias, operated by the Laboratório Nacional de Astrofísicaand the MDM Observatory at Kitt Peak.
| 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.
| A catalogue and analysis of X-ray luminosities of early-type galaxies
We present a catalogue of X-ray luminosities for 401 early-typegalaxies, of which 136 are based on newly analysed ROSAT PSPC pointedobservations. The remaining luminosities are taken from the literatureand converted to a common energy band, spectral model and distancescale. Using this sample we fit the LX:LB relationfor early-type galaxies and find a best-fit slope for the catalogue of~2.2. We demonstrate the influence of group-dominant galaxies on the fitand present evidence that the relation is not well modelled by a singlepower-law fit. We also derive estimates of the contribution to galaxyX-ray luminosities from discrete-sources and conclude that they provideLdscr/LB~=29.5ergs-1LBsolar-1. Wecompare this result with luminosities from our catalogue. Lastly, weexamine the influence of environment on galaxy X-ray luminosity and onthe form of the LX:LB relation. We conclude thatalthough environment undoubtedly affects the X-ray properties ofindividual galaxies, particularly those in the centres of groups andclusters, it does not change the nature of whole populations.
| Line-of-sight velocity distributions of low-luminosity elliptical galaxies
The shape of the line-of-sight velocity distribution (LOSVD) is measuredfor a sample of 14 elliptical galaxies, predominantly low-luminosityellipticals. The sample is dominated by galaxies in the Virgo clusterbut also contains ellipticals in nearby groups and low-densityenvironments. The parametrization of the LOSVD given by Gerhard and vander Marel & Franx is adopted, which measures the asymmetrical andsymmetrical deviations of the LOSVD from a Gaussian by the amplitudesh3 and h4 of the Gauss-Hermite series. Rotation,velocity dispersion, h3 and h4 are determined as afunction of radius for both major and minor axes. Non-Gaussian LOSVDsare found for all galaxies along the major axes. Deviations from aGaussian LOSVD along the minor axis are of much lower amplitude ifpresent at all. Central decreases in velocity dispersion are found forthree galaxies. Two galaxies have kinematically decoupled cores: NGC4458and the well-known case of NGC3608.
| Nearby Optical Galaxies: Selection of the Sample and Identification of Groups
In this paper we describe the Nearby Optical Galaxy (NOG) sample, whichis a complete, distance-limited (cz<=6000 km s-1) andmagnitude-limited (B<=14) sample of ~7000 optical galaxies. Thesample covers 2/3 (8.27 sr) of the sky (|b|>20deg) andappears to have a good completeness in redshift (97%). We select thesample on the basis of homogenized corrected total blue magnitudes inorder to minimize systematic effects in galaxy sampling. We identify thegroups in this sample by means of both the hierarchical and thepercolation ``friends-of-friends'' methods. The resulting catalogs ofloose groups appear to be similar and are among the largest catalogs ofgroups currently available. Most of the NOG galaxies (~60%) are found tobe members of galaxy pairs (~580 pairs for a total of ~15% of objects)or groups with at least three members (~500 groups for a total of ~45%of objects). About 40% of galaxies are left ungrouped (field galaxies).We illustrate the main features of the NOG galaxy distribution. Comparedto previous optical and IRAS galaxy samples, the NOG provides a densersampling of the galaxy distribution in the nearby universe. Given itslarge sky coverage, the identification of groups, and its high-densitysampling, the NOG is suited to the analysis of the galaxy density fieldof the nearby universe, especially on small scales.
| 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 3D structure of the Virgo cluster from H-band Fundamental Plane and Tully-Fisher distance determinations
We undertook a surface photometry survey of 200 galaxies in the Virgocluster (complete to B<14.0 mag) carried out in the near-infrared(NIR) H band. Combining velocity dispersion measurements from theliterature with new spectroscopic data for 11 galaxies, we derivedistances of 59 early-type galaxies using the Fundamental Plane (FP)method. The distances of another 75 late-type galaxies are determinedusing the Tully-Fisher (TF) method. For this purpose we use the maximumrotational velocity, as derived from HI spectra from the literature,complemented with new Hα rotation curves of eight highlyHI-deficient galaxies. The zero-points of the FP and TF templaterelations are calibrated assuming the distance modulus of Virgomu_0=31.0, as determined with the Cepheids method. Using these 134distance determinations (with individual uncertainties of 0.35 mag (TF)and 0.45 mag (FP)) we find that the distance of cluster A, associatedwith M87, is mu_0=30.84 +/- 0.06. Cluster B, offset to the south, isfound at mu_0=31.84 +/- 0.10. This subcluster is falling on to A atabout 750 km s^-1. Clouds W and M are at twice the distance of A.Galaxies on the north-west and south-east of the main cluster A belongto two clouds composed almost exclusively of spiral galaxies withdistances consistent with A, but with significantly different velocitydistributions, suggesting that they are falling on to cluster A atapproximately 770 km s^-1 from the far side and at 200 km s^-1 from thenear side respectively. The mass of Virgo inferred from the peculiarmotions induced on its vicinity is consistent with the virialexpectation.
| X-ray luminosities for a magnitude-limited sample of early-type galaxies from the ROSAT All-Sky Survey
For a magnitude-limited optical sample (B_T <= 13.5 mag) ofearly-type galaxies, we have derived X-ray luminosities from the ROSATAll-Sky Survey. The results are 101 detections and 192 useful upperlimits in the range from 10^36 to 10^44 erg s^-1. For most of thegalaxies no X-ray data have been available until now. On the basis ofthis sample with its full sky coverage, we find no galaxy with anunusually low flux from discrete emitters. Below log (L_B) ~ 9.2L_⊗ the X-ray emission is compatible with being entirely due todiscrete sources. Above log (L_B) ~ 11.2 L_osolar no galaxy with onlydiscrete emission is found. We further confirm earlier findings that L_xis strongly correlated with L_B. Over the entire data range the slope isfound to be 2.23 (+/- 0.12). We also find a luminosity dependence ofthis correlation. Below log L_x = 40.5 erg s^-1 it is consistent with aslope of 1, as expected from discrete emission. Above this value theslope is close to 2, as expected from gaseous emission. Comparing thedistribution of X-ray luminosities with the models of Ciotti et al.leads to the conclusion that the vast majority of early-type galaxiesare in the wind or outflow phase. Some of the galaxies may have alreadyexperienced the transition to the inflow phase. They show X-rayluminosities in excess of the value predicted by cooling flow modelswith the largest plausible standard supernova rates. A possibleexplanation for these super X-ray-luminous galaxies is suggested by thesmooth transition in the L_x--L_B plane from galaxies to clusters ofgalaxies. Gas connected to the group environment might cause the X-rayoverluminosity.
| 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.
| Stellar populations in dwarf elliptical galaxies.
Not Available
| Groups of galaxies. III. Some empirical characteristics.
Not Available
| Total magnitude, radius, colour indices, colour gradients and photometric type of galaxies
We present a catalogue of aperture photometry of galaxies, in UBVRI,assembled from three different origins: (i) an update of the catalogueof Buta et al. (1995) (ii) published photometric profiles and (iii)aperture photometry performed on CCD images. We explored different setsof growth curves to fit these data: (i) The Sersic law, (ii) The net ofgrowth curves used for the preparation of the RC3 and (iii) A linearinterpolation between the de Vaucouleurs (r(1/4) ) and exponential laws.Finally we adopted the latter solution. Fitting these growth curves, wederive (1) the total magnitude, (2) the effective radius, (3) the colourindices and (4) gradients and (5) the photometric type of 5169 galaxies.The photometric type is defined to statistically match the revisedmorphologic type and parametrizes the shape of the growth curve. It iscoded from -9, for very concentrated galaxies, to +10, for diffusegalaxies. Based in part on observations collected at the Haute-ProvenceObservatory.
| A catalogue of spatially resolved kinematics of galaxies: Bibliography
We present a catalogue of galaxies for which spatially resolved data ontheir internal kinematics have been published; there is no a priorirestriction regarding their morphological type. The catalogue lists thereferences to the articles where the data are published, as well as acoded description of these data: observed emission or absorption lines,velocity or velocity dispersion, radial profile or 2D field, positionangle. Tables 1, 2, and 3 are proposed in electronic form only, and areavailable from the CDS, via anonymous ftp to cdsarc.u-strasbg.fr (to130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html
| Molecular Gas in Elliptical Galaxies: CO Observations of an IRAS Flux-limited Sample
A search for CO(2-1) emission from 42 early-type galaxies with 100micron flux densities greater than 1 Jy detected (tentatively in somecases) 11 galaxies and tentatively found absorption against the activenucleus in two. Data from this survey and from the literature show thatthe overall detection rate of CO emission or absorption in ellipticalgalaxies is 45% and that the detection rate increases with increasing100 micron flux density. The data suggest that all elliptical galaxiescontain a small amount of cold interstellar matter. The CO andfar-infrared fluxes are well correlated, though the relationship shows alot of scatter, which does not appear to be caused by variations in thetemperature of the interstellar dust and probably indicates differencesin the physical state of the interstellar medium from galaxy to galaxy.The CO flux densities are completely uncorrelated with the galacticstarlight. The detection of CO emission shows that many ellipticalgalaxies have dense cold gas in their inner regions. The four galaxieswhich are known to have CO absorption, including the two from thepresent paper, have relatively narrow absorption components which are atthe galaxy's systemic velocity and/or redshifted with respect to thisvelocity, consistent with infall to the center of the galaxy.
| 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.
| The fundamental plane of early-type galaxies: stellar populations and mass-to-light ratio.
We analyse the residuals to the fundamental plane (FP) of ellipticalgalaxies as a function of stellar-population indicators; these are basedon the line-strength parameter Mg_2_ and on UBVRI broad-band colors, andare partly derived from new observations. The effect of the stellarpopulations accounts for approximately half the observed variation ofthe mass-to-light ratio responsible for the FP tilt. The residual tiltcan be explained by the contribution of two additional effects: thedependence of the rotational support, and possibly that of the spatialstructure, on the luminosity. We conclude to a constancy of thedynamical-to-stellar mass ratio. This probably extends to globularclusters as well, but the dominant factor would be here the luminositydependence of the structure rather than that of the stellar population.This result also implies a constancy of the fraction of dark matter overall the scalelength covered by stellar systems. Our compilation ofinternal stellar kinematics of galaxies is appended.
| A Catalog of Stellar Velocity Dispersions. II. 1994 Update
A catalog of central velocity dispersion measurements is presented,current through 1993 September. The catalog includes 2474 measurementsof 1563 galaxies. A standard set of 86 galaxies is defined, consistingof galaxies with at least three reliable, concordant measurements. It issuggested that future studies observe some of these standard galaxies sothat different studies can be normalized to a consistent system. Allmeasurements are reduced to a normalized system using these standards.
| The UV properties of normal galaxies. III. Standard luminosity profiles and total magnitudes.
In the previous papers of this series we collected and reduced to thesame system all the available photometric data obtained in theultraviolet (UV) range for normal (i.e. non active) galaxies. Here weuse these data to derive standard UV luminosity profiles for threemorphological bins (E/S0; Sa/Sb; Sc/Sd) and extrapolated totalmagnitudes for almost 400 galaxies. We find that: 1) the UV growthcurves are well matched by the B-band revised standard luminosityprofiles, once a proper shift in the effective radius is applied, and 2)the UV light in early-type galaxies is more centrally concentrated thanthe visible light.
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