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Circumnuclear Structure and Black Hole Fueling: Hubble Space Telescope NICMOS Imaging of 250 Active and Normal Galaxies
Why are the nuclei of some galaxies more active than others? If mostgalaxies harbor a central massive black hole, the main difference isprobably in how well it is fueled by its surroundings. We investigatethe hypothesis that such a difference can be seen in the detailedcircumnuclear morphologies of galaxies using several quantitativelydefined features, including bars, isophotal twists, boxy and diskyisophotes, and strong nonaxisymmetric features in unsharp-masked images.These diagnostics are applied to 250 high-resolution images of galaxycenters obtained in the near-infrared with NICMOS on the Hubble SpaceTelescope. To guard against the influence of possible biases andselection effects, we have carefully matched samples of Seyfert 1,Seyfert 2, LINER, starburst, and normal galaxies in their basicproperties, taking particular care to ensure that each was observed witha similar average scale (10-15 pc pixel-1). Severalmorphological differences among our five different spectroscopicclassifications emerge from the analysis. The H II/starburst galaxiesshow the strongest deviations from smooth elliptical isophotes, whilethe normal galaxies and LINERs have the least disturbed morphology. TheSeyfert 2s have significantly more twisted isophotes than any othercategory, and the early-type Seyfert 2s are significantly more disturbedthan the early-type Seyfert 1s. The morphological differences betweenSeyfert 1s and Seyfert 2s suggest that more is at work than simply theviewing angle of the central engine. They may correspond to differentevolutionary stages.
| The Near-Infrared Ca II Triplet-σ Relation for Bulges of Spiral Galaxies
We present measurements of the near-infrared Ca II triplet (CaT, CaT*),Paschen (PaT), and magnesium (Mg I) indices for a well-studied sample of19 bulges of early to intermediate spiral galaxies. We find that boththe CaT* and CaT indices decrease with central velocity dispersionσ with small scatter. This dependence is similar to that recentlyfound by Cenarro for elliptical galaxies, implying a uniformCaT*-σ relation that applies to galaxies from ellipticals tointermediate-type spirals. The decrease of CaT and CaT* with σcontrasts with the well-known increase of another α-element index,Mg2, with σ. We discuss the role of Ca underabundance([Ca/Fe]<0) and initial mass function variations in the onset of theobserved relations.
| Galactic Bulges from Hubble Space Telescope Near-Infrared Camera Multi-Object Spectrometer Observations: The Lack of r1/4 Bulges
We use Hubble Space Telescope (HST) near-infrared imaging to explore theshapes of the surface brightness profiles of bulges of S0-Sbc galaxiesat high resolution. Modeling extends to the outer bulge via bulge-diskdecompositions of combined HST-ground-based profiles. Compact, centralunresolved components similar to those reported by others are found in~84% of the sample. We also detect a moderate frequency (~34%) ofnuclear components with exponential profiles that may be disks or bars.Adopting the Sérsic r1/n functional form for thebulge, none of the bulges have an r1/4 behavior; derivedSérsic shape indices are =1.7+/-0.7. For the same sample, fitsto near-infrared ground-based profiles yield Sérsic indices up ton=4-6. The high n of ground-based profiles are the result of nuclearpoint sources blending with the extended light of the bulge because ofseeing. The low Sérsic indices are not expected from violentrelaxation in mergers. Based on observations made with the NASA/ESAHubble Space Telescope, obtained at the Space Telescope ScienceInstitute, which is operated by the Association of Universities forResearch in Astronomy, Inc., under NASA contract NAS 5-26555.
| Minor axis kinematics of 19 S0-Sbc bulges
We present minor axis kinematic profiles for a well-studied sample of 19early- to intermediate-type disk galaxies. We introduce, for the firsttime, the use of single-burst stellar population (SSP) models to obtainstellar velocities, velocity dispersions and higher order Gauss-Hermitemoments (h3, h4) from galaxy spectra in thenear-infrared Ca II triplet region. SSP models, which employs thesynthetic spectra of \citet{vazdekis03}, provide a means to address thetemplate-mismatch problem, and are shown to provide as good or betterfits as traditional stellar templates. We anticipate the technique to beof particular use for high-redshift galaxy kinematics. We give themeasurement of a recently defined CaT* index\citep{cenarro01}, and describe the global properties of the bulgekinematics as derived from the kinematic profiles. We detectsmall-amplitude minor-axis rotation, generally due to inner isophotaltwists as a result of slightly triaxial bulges or misaligned innerdisks; such inner features do not show peculiar colors or distinctCaT* index values. Velocity dispersion profiles, which extendwell into the disk region, show a wide range of slopes. Flattened bulgestend to have shallower velocity dispersion profiles. The inferredsimilarity of bulge and disk radial velocity dispersions supports theinterpretation of these bulges as thickened disks.Appendix B is only available in electronic form athttp://www.edpsciences.org
| Bulges on the Fundamental Plane of early-type galaxies
In an ongoing effort to study the formation and evolution of galacticbulges, we have investigated the position of 19 bulges of type S0-Sbc onthe Fundamental Plane (FP). We find that bulges, in both B and K band,lie close to but slightly below the FP defined by ellipticals and S0s,i.e. are slightly brighter. There are hints that bulges of latermorphological type are situated below the other bulges in our sample.The FP results are consistent with the picture, obtained from our recentanalysis of HST colours, that bulges are old, except for the Sbcgalaxies. The fact that bulges lie so close to the FP of ellipticals andS0s implies that their formation epoch must have been similar to, atmost about 2.5 Gyr earlier than, cluster Es and S0s, and that thesurrounding disc does not significantly affect their structure.
| The origin of the strings in the outer regions of η Carinae
The narrow optical filaments (`strings' or `spikes') emerging from theHomunculus of η Carinae are modelled as resulting from the passageof ballistic `bullets' of material through the dense circumstellarenvironment. In this explanation, the string is the decelerating flow ofablated gas from the bullet. An archive Hubble Space Telescope image andnew forbidden-line profiles of the most distinct of the strings arepresented and discussed in terms of this simple model.
| 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.
| Correlations among Global Photometric Properties of Disk Galaxies
Using a two-dimensional galaxy image decomposition technique, we extractglobal bulge and disk parameters for a complete sample of early-typedisk galaxies in the near-infrared K band. We find significantcorrelation of the bulge parameter n with the central bulge surfacebrightness μb(0) and with effective radiusre. Using bivariate analysis techniques, we findthat logn, logre, and μb(0) are distributed ina plane with small scatter. We do not find a strong correlation of nwith bulge-to-disk luminosity ratio, contrary to earlier reports. Forthese early-type disk galaxies, re and the diskscale length rd are well correlated, but withlarge scatter. We examine the implications of our results for variousbulge formation scenarios in disk galaxies.
| Box- and peanut-shaped bulges. I. Statistics
We present a classification for bulges of a complete sample of ~ 1350edge-on disk galaxies derived from the RC3 (Third Reference Catalogue ofBright Galaxies, de Vaucouleurs et al. \cite{rc3}). A visualclassification of the bulges using the Digitized Sky Survey (DSS) inthree types of b/p bulges or as an elliptical type is presented andsupported by CCD images. NIR observations reveal that dust extinctiondoes almost not influence the shape of bulges. There is no substantialdifference between the shape of bulges in the optical and in the NIR.Our analysis reveals that 45% of all bulges are box- and peanut-shaped(b/p). The frequency of b/p bulges for all morphological types from S0to Sd is > 40%. In particular, this is for the first time that such alarge frequency of b/p bulges is reported for galaxies as late as Sd.The fraction of the observed b/p bulges is large enough to explain theb/p bulges by bars. Partly based on observations collected at ESO/LaSilla (Chile), DSAZ/Calar Alto (Spain), and Lowell Observatory/Flagstaff(AZ/U.S.A.). Tables 6 and 7 are only available in electronic form at CDSvia anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| Galactic bulges from Hubble Space Telescope NICMOS observations: ages and dust
We present optical and near-infrared colour maps of the central regionsof bulges of S0 and spiral galaxies obtained with WFPC2 and NICMOS onthe Hubble Space Telescope (HST). By combined use of HST andground-based data, the colour information spans a region from a few tensof pc to a few kpc. In almost all galaxies, the colour profiles in thecentral 100-200pc become more rapidly redder. We attribute the highcentral colour indices to a central concentration of dust. We infer anaverage extinction at the centre of AV=0.6-1.0mag. Severalobjects show central dust rings or discs at subkpc scales similar tothose found by others in giant ellipticals. For galactic bulges of typesS0 to Sb, the tightness of the B-I versus I-H relation suggests that theage spread among bulges of early-type galaxies is small, at most 2Gyr.Colours at 1Reff, where we expect extinction to benegligible, are similar to those of elliptical galaxies in the Comacluster, suggesting that these bulges formed at the same time as thebright galaxies in Coma. Furthermore, the galaxy ages are found to beindependent of their environment. As it is likely that Coma was formedat redshift z>3, our bulges, which are in groups and in the field,must also have been formed at this epoch. Bulges of early-type spiralscannot be formed by secular evolution of bars at recent epochs, becausesuch bulges would be much younger. There are three galaxies of type Sbcand later; their bulges are younger and could perhaps arise from secularevolution of transient bars. Our results are in good agreement withsemi-analytic predictions, which also predict that bulges, in clustersand in the field, are as old as giant ellipticals in clusters.
| 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.
| Look-alike galaxies:. HI observations for look-alike galaxies of four calibrators
We present a programme aiming at applying the Tully-Fisher relation forgalaxies with the same morphological type and the same inclination(look-alike galaxies or sosie galaxies) as calibrating galaxies. Theadvantage of sosie galaxies is discussed. In particular, it is shownthat using sosies of bright calibrators will allow us to explore theuniverse deeper and more efficiently than the classical TF methodapplied to different morphological types and different inclinations. Asa preliminary part, we report in this paper new HI observationsperformed with the radiotelescope of Nançay (France) for sosiesof four calibrators NGC 224, NGC 3031, NGC 253 and NGC 5457. 82 galaxieswere detected. These observations made use of Nançayradiotelescope. The Nançay Radio Observatory is the Unitéscientifique de Nançay of the Observatoire de Paris,associated asUnité de Service et de Recherche (USR) No. B704 to the FrenchCentre National de la Recherche Scientifique (CNRS). The NançayObservatory also acknowledges the financial support of the ConseilRégional of the Région Centre in France.
| Groups of galaxies. III. Some empirical characteristics.
Not Available
| Kinematics of the local universe. VII. New 21-cm line measurements of 2112 galaxies
This paper presents 2112 new 21-cm neutral hydrogen line measurementscarried out with the meridian transit Nan\c cay radiotelescope. Amongthese data we give also 213 new radial velocities which complement thoselisted in three previous papers of this series. These new measurements,together with the HI data collected in LEDA, put to 6 700 the number ofgalaxies with 21-cm line width, radial velocity, and apparent diameterin the so-called KLUN sample. Figure 5 and Appendices A and B forcorresponding comments are available in electronic form at thehttp://www.edpsciences.com
| Near-infrared surface photometry of bulges and disks of spiral galaxies. The data
We present optical and near-infrared (NIR) surface brightness and colourprofiles, in bands ranging from U to K, for the disk and bulgecomponents of a complete sample of 30 nearby S0 to Sbc galaxies withinclinations larger than 50 deg. We describe in detail the observationsand the determination of colour parameters. Calibrated monochromatic andreal-colour images are presented, as well as colour index maps. Thisdata set, tailored for the study of the population characteristics ofgalaxy bulges, provides useful information on the colours of inner disksas well. In related papers, we have used them to quantify colourgradients in bulges, and age differentials between bulge and inner disk.
| Ages of Galaxies Bulges and Disks From Optical and Near-Infrared Colors
We compare optical and near-infrared colors of disks and bulges in adiameter-limited sample of inclined, bright, nearby, early-type spirals.Color profiles along wedge apertures at 15^deg^ from the major axis andon the minor axis on the side of the galaxy opposite to the dust laneare used to assign nominal colors for the inner disks (at 2 scalelength) and for the bulges (~0.5r_eff_), respectively. We estimate thatthe effects of dust reddening and the cross-talk between the colors ofthe two components is negligible. We find that color differences(bulge-disk) are very small: {DELTA}(U-R) = 0.126+/-0.165,{DELTA}(R-K)=0078+/-0.165. Disks tend to be bluer by an amount threetimes smaller than that reported by Bothun & Gregg [ApJ,350,73(1990)] for S0s. Color variations from galaxy to galaxy are muchlarger than color differences between disk and bulge in each galaxy.Probably, the underlying old population of disks and bulges is much moresimilar than the population paradigm would lead us to believe. Impliedage differences, assuming identical metallicities, are less than 30%.
| 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.
| Global H I profiles of spiral galaxies.
In this paper we present short H I synthesis observations of 57 galaxieswithout H I information in the RC3. These are a by-product of a largesurvey with the WSRT of the neutral hydrogen gas in spiral and irregulargalaxies. Global profiles and related quantities are given for the 42detected galaxies and upper limits for the remaining 15. A number ofgalaxies have low values of H I mass-to-blue luminosity ratio.
| The Shape of the Luminosity Profiles of Bulges of Spiral Galaxies
Using a 2D generalization of Kent's model-independent decompositionmethod, we extract the K-band light profiles of the bulges of a sampleof field galaxies with morphological types ranging from S0 to Sbc. Wethen examine the shape of the bulge profiles, by means of fitting aseeing-convolved power law of the form μ(r) is proportional tor^1/n^, where the exponent n is allowed to vary. The best-fittingexponent n is found to vary systematically from values around 1(exponential) to 6 from late- to early- type bulges; the profiles tendto fall off more steeply in the outer parts for the later types. Thesame trend is seen as a function of bulge to disc ratio. Application ofthe method to artificial data proves that this result is not caused bydisc-light contamination. There are also indications that n becomeslarger with increasing total luminosity and radius of the bulge. Asimilar relation has recently been found for elliptical galaxies. Thesmooth trend of n with morphological type shows that the formation of orinteraction with the disc has affected the density distribution of thebulge.
| Colors and color gradients in bulges of galaxies
We have obtained surface photometry in U, B, R, and I for a completeoptically selected sample of 45 early-type spiral galaxies, toinvestigate the colors and color gradients of spiral bulges. Colorprofiles in U-R, B-R, U-B, and R-I have been determined in wedgesopening on the semiminor axes. Based on several criteria, like thesmoothness of the color profiles, the absence of dust lanes, and thecentral colors, we have defined a subsample of 18 objects whose colorsare largely unaffected by dust. We believe such colors are suitable forinferring properties of the stellar populations of bulges. We find thatthe colors of bulges are predominantly bluer than those of ellipticals.This result holds even when bulges are compared to ellipticals of thesame luminosity, and indicates that bulges are younger and/or more metalpoor than old elliptical galaxies. Most bulges do not reach solarmetallicities. Bulges show predominantly negative color gradients (blueroutward). For bright bulges (MBulgeR is less than-20.0), the magnitude of the gradient increases with bulge luminosity.For fainter bulges, gradients scatter around large negative values. Thebehavior of color gradients as a function of bulge luminosity suggestsdifferent formation mechanisms for faint and bright spheroids. Forbright bulges, the scaling of gradients with luminosity suggests aformation process involving dissipation. The similarity with ellipticalssuggests that the formation of the disk did not affect the stellarpopulations of the bulge in a major way. For small bulges (MRis greater than -20), the existence of pronounced color gradientssuggests a different formation mechanism. For these objects, thepresence of the disk may have severely affected the radial populationdistribution in the bulge.
| A revised catalog of CfA1 galaxy groups in the Virgo/Great Attractor flow field
A new identification of groups and clusters in the CfA1 Catalog ofHuchra et al. is presented, using a percolation algorithm to identifydensity enhancements. It is shown that in the resulting catalog,contamination by interlopers is significantly reduced. The Schechterluminosity function is redetermined, including the Malmquist bias.
| General study of group membership. II - Determination of nearby groups
We present a whole sky catalog of nearby groups of galaxies taken fromthe Lyon-Meudon Extragalactic Database. From the 78,000 objects in thedatabase, we extracted a sample of 6392 galaxies, complete up to thelimiting apparent magnitude B0 = 14.0. Moreover, in order to considersolely the galaxies of the local universe, all the selected galaxieshave a known recession velocity smaller than 5500 km/s. Two methods wereused in group construction: a Huchra-Geller (1982) derived percolationmethod and a Tully (1980) derived hierarchical method. Each method gaveus one catalog. These were then compared and synthesized to obtain asingle catalog containing the most reliable groups. There are 485 groupsof a least three members in the final catalog.
| Groups of galaxies within 80 Mpc. II - The catalogue of groups and group members
This paper gives a catalog of the groups and associations obtained bymeans of a revised hierarchical algorithm applied to a sample of 4143galaxies with diameters larger than 100 arcsec and redshifts smallerthan 6000 km/s. The 264 groups of galaxies obtained in this way (andwhich contain at least three sample galaxies) are listed, with the looseassociations surrounding them and the individual members of eachaggregate as well; moreover, the location of every entity among 13regions corresponding roughly to superclusters is specified. Finally,1729 galaxies belong to the groups, and 466 to the associations, i.e.,the total fraction of galaxies within the various aggregates amounts to53 percent.
| The far-infrared properties of the CfA galaxy sample. I - The catalog
IRAS flux densities are presented for all galaxies in the Center forAstrophysics magnitude-limited sample (mB not greater than 14.5)detected in the IRAS Faint Source Survey (FSS), a total of 1544galaxies. The detection rate in the FSS is slightly larger than in thePSC for the long-wavelength 60- and 100-micron bands, but improves by afactor of about 3 or more for the short wavelength 12- and 25-micronbands. This optically selected sample consists of galaxies which are, onaverage, much less IR-active than galaxies in IR-selected samples. Itpossesses accurate and complete redshift, morphological, and magnitudeinformation, along with observations at other wavelengths.
| Galaxy alignments
Large areas of the sky around the brightest apparent magnitude galaxieshave been examined. In almost every case where they are not crowded byother right galaxies, clearly marked lines of higher red shift galaxieshave been going through, or originating from, the positions of thesebright apparent magnitude galaxies. It is shown that galaxies of about3000 to 5000 km/s red shift define narrow filaments of from 10 to 50 degin length. It is found that galaxies of very bright apparent magnitudetend to occur at the center or ends of these alignments. The 20brightest galaxies in apparent magnitude north of delta = 0 deg areinvestigated here. Of the 14 which are uncrowded by nearby brightgalaxies, a total of 13 have well marked-lines and concentrations offainter, higher red shift galaxies.
| A search for environmental effects on the optical properties of galaxies in groups
Environmental density-related modifications of basic optical properties(luminosities, sizes, axial ratios, and colors) of galaxies belonging toGeller and Huchra's (1983) groups have been investigated. Remarkably, itis found that the broad maxima of the distributions of luminosities anddiameters of spirals and the whole corresponding distributions oflenticulars tend to move to lower values as one goes to groups of highcompactness, whereas the luminosity-diameter relationship of spiralstends to become flatter. No color and axial ratio differences betweengalaxies of high- and low-compactness groups have been detected.
| A survey of galaxy redshifts. IV - The data
The complete list of the best available radial velocities for the 2401galaxies in the merged Zwicky-Nilson catalog brighter than 14.5mz and with b (II) above +40 deg or below -30 deg ispresented. Almost 60 percent of the redshifts are from the CfA surveyand are accurate to typically 35 km/s.
| A catalog of hierarchical subclustering in the Turner-Gott groups
Information on the substructure, to four levels of hierarchy, ispresented for the 103 groups listed by Turner and Gott (TG) in theircatalog of groups of galaxies. All galaxies brighter than Mpg= 14.0 in the region delta is 0 deg or greater and b(II) is 40 deg orgreater that have been assigned group memberships by TG are included.Also listed is the local environmental information for each of thegalaxies, giving the surface density enhancement beta in the galaxy'sneighborhood, calculated at 15 levels in the range beta = 4.6 to 10,000.
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