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The distribution of atomic gas and dust in nearby galaxies - III. Radial distributions and metallicity gradients
The radial distribution of dust and gas in 38 nearby galaxies isinvestigated, using a sample of galaxies for which matched resolution(25 arcsec) neutral hydrogen (HI) and 850-μm images are available.Most of these radial profiles are fitted well by an exponential model,and the derived 850-μm scalelengths are proportional to the HIscalelengths. From this relation, it is found that the metallicitygradients of these galaxies are much shallower than previous studies,unless the dust temperature is constant within the disc, or asignificant component of molecular gas exists at large radii that is nottraced by CO observations.
| The distribution of atomic gas and dust in nearby galaxies - II. Further matched-resolution Very Large Array H I and SCUBA 850-μm images
We present Very Large Array (VLA) C-array 21-cm HI images of galaxiesfrom the SCUBA Local Universe Galaxy Survey which have been observed at850 μm with the James Clerk Maxwell Telescope. Matched-resolution (~25 arcsec) HI images of 17 galaxies are presented and compared with850-μm images. HI or 850-μm images of an additional six galaxieswhich were detected at only one wavelength are presented. Additionally,lower resolution H I observations of nine galaxies are presented. Theobservations of these galaxies, along with results previously presented,do not show any obvious trends in the HI/dust or H2/dust massratios with morphological type.
| Luminous Compact Blue Galaxies in the Local Universe
We use the KPNO International Spectroscopic Survey (KISS) foremission-line galaxies to identify and describe a sample of localanalogs to the luminous compact blue galaxies (LCBGs) that are observedto be abundant at intermediate and high redshift. The sample is selectedusing criteria believed effective at isolating true examples of LCBGs:SBe(Bband)<21.0 mag arcsec-2,MB<-18.5 (for H0=75 km s-1Mpc-1), and B-V<0.6. In addition, all LCBG candidatespresented are selected to have star formation as their dominant form ofactivity. We examine the properties of our LCBGs and compare them withthose of other KISS star-forming galaxies of the same absolute magnituderange. We find that the KISS LCBGs lie on the extreme end of a fairlycontinuous distribution of ``normal'' star-forming galaxies in the planeof surface brightness versus color. This result differs from the resultsof previous studies that show LCBGs at higher z to be more separate fromthe ``normal'' (usually nonactive) galaxies with which they arecompared. On average, LCBGs have a higher tendency to emit detectableflux in the radio continuum; have higher Hα luminosities by afactor of 1.6, indicating strong star formation activity; and haveslightly lower than expected metal abundances based on theluminosity-metallicity relation for KISS galaxies. We calculate thevolume density of our low-z (z<0.045) sample to be5.4×10-4 h375 Mpc-3,approximately 4 times lower than the volume density of the LCBGs at0.4
| Inner-truncated Disks in Galaxies
We present an analysis of the disk brightness profiles of 218 spiral andlenticular galaxies. At least 28% of disk galaxies exhibit innertruncations in these profiles. There are no significant trends oftruncation incidence with Hubble type, but the incidence among barredsystems is 49%, more than 4 times that for nonbarred galaxies. However,not all barred systems have inner truncations, and not allinner-truncated systems are currently barred. Truncations represent areal dearth of disk stars in the inner regions and are not an artifactof our selection or fitting procedures nor the result of obscuration bydust. Disk surface brightness profiles in the outer regions are wellrepresented by simple exponentials for both truncated and nontruncateddisks. However, truncated and nontruncated systems have systematicallydifferent slopes and central surface brightness parameters for theirdisk brightness distributions. Truncation radii do not appear tocorrelate well with the sizes or brightnesses of the bulges. Thissuggests that the low angular momentum material apparently missing fromthe inner disk was not simply consumed in forming the bulge population.Disk parameters and the statistics of bar orientations in our sampleindicate that the missing stars of the inner disk have not simply beenredistributed azimuthally into bar structures. The sharpness of thebrightness truncations and their locations with respect to othergalactic structures suggest that resonances associated with diskkinematics, or tidal interactions with the mass of bulge stars, might beresponsible for this phenomenon.
| Radio Continuum Emission at 1.4 GHz from KISS Emission-Line Galaxies
We have searched the Faint Images of the Radio Sky at Twenty centimeters(FIRST) and the NRAO VLA Sky Survey (NVSS) 1.4 GHz radio surveys forsources that are coincident with emission-line galaxy (ELG) candidatesfrom the KPNO International Spectroscopic Survey (KISS). A total of 207of the 2157 KISS ELGs (~10%) in the first two Hα-selected surveylists were found to possess radio detections in FIRST, NVSS, or both.Follow-up spectra exist for all of the radio detections, allowing us todetermine the activity type (star-forming vs. active nucleus) for theentire sample. We explore the properties of the radio-detected KISSgalaxies in order to gain a better insight into the nature ofradio-emitting galaxies in the local universe (z<0.1). No dwarfgalaxies were detected, despite the large numbers of low-luminositygalaxies present in KISS, suggesting that lower mass, lower luminosityobjects do not possess strong galaxian-scale magnetic fields. Because ofthe selection technique used for KISS, our radio ELGs represent aquasi-volume-limited sample, which allows us to develop a clearerpicture of the radio galaxy population at low redshift. Nearlytwo-thirds of the KISS radio galaxies are starburst or star-forminggalaxies, which is in stark contrast to the results of flux-limitedradio surveys, which are dominated by active galactic nuclei (AGNs) andelliptical galaxies (i.e., classical radio galaxies). While there aremany AGNs among the KISS radio galaxies, there are no objects with largeradio powers in our local volume. We derive a radio luminosity function(RLF) for the KISS ELGs that agrees very well with previous RLFs thatadequately sample the lower luminosity radio population.
| Dust masses and star formation in bright IRAS galaxies. Application of a physical model for the interpretation of FIR observations
We address the problem of modeling the far-infrared (FIR) spectrum andderiving the star-formation rate (SFR) and the dust mass of spiralgalaxies. We use the realistic physical model of Popescu et al.(\cite{popescu}) to describe the overall ultra-violet (UV), optical andFIR spectral energy distribution (SED) of a spiral galaxy. The modeltakes into account the 3-dimensional old and young stellar distributionsin the bulge and the disk of a galaxy, together with the dust geometry.The geometrical characteristics of the galaxy and the intrinsic opticaland near-infrared spectra are determined by the galaxy's observed K-bandphotometry. The UV part of the spectrum is assumed to be proportional tothe SFR through the use of population synthesis models. By solving theradiative transfer equation, we are able to determine the absorbedenergy, the dust temperature and the resulting FIR spectrum. The modelhas only three free parameters: SFR, dust mass, and the fraction of theUV radiation which is absorbed locally by dense dust in the HII regions.Using this model, we are able to fit well the FIR spectra of 62 brightIRAS galaxies from the ``SCUBA Local Universe Galaxy Survey" of Dunne etal. (\cite{dunne1}). As a result, we are able to determine, amongothers, their SFR and dust mass. We find that, on average, the SFR (inabsolute units), the star-formation efficiency, the SFR surface densityand the ratio of FIR luminosity over the total intrinsic luminosity, arelarger than the respective values of typical spiral galaxies of the samemorphological type. We also find that the mean gas-to-dust mass ratio isclose to the Galactic value, while the average central face-on opticaldepth of these galaxies in the V band is 2.3. Finally, we find a strongcorrelation between SFR or dust mass and observed FIR quantities liketotal FIR luminosity or FIR luminosity at 100 and 850 μm. Thesecorrelations yield well-defined relations, which can be used todetermine a spiral galaxy's SFR and dust-mass content from FIRobservations.
| CO Molecular Gas in Infrared-luminous Galaxies
We present the first statistical survey of the properties of the12CO(1-0) and 12CO(3-2) line emission from thenuclei of a nearly complete subsample of 60 infrared (IR) luminousgalaxies selected from SCUBA Local Universe Galaxy Survey (SLUGS). Thissubsample is flux limited at S60μm>=5.24 Jy with far-IR(FIR) luminosities mostly at LFIR>1010Lsolar. We compare the emission line strengths of12CO(1-0) and (3-2) transitions at a common resolution of~15". The measured 12CO(3-2) to (1-0) line intensity ratiosr31 vary from 0.22 to 1.72, with a mean value of 0.66 for thesources observed, indicating a large spread of the degree of excitationof CO in the sample. These CO data, together with a wide range of dataat different wavelengths obtained from the literature, allow us to studythe relationship between the CO excitation conditions and the physicalproperties of gas/dust and star formation in the central regions ofgalaxies. Our analysis shows that there is a nonlinear relation betweenCO and FIR luminosities, such that their ratioLCO/LFIR decreases linearly with increasingLFIR. This behavior was found to be consistent with theSchmidt law relating star formation rate to molecular gas content, withan index N=1.4+/-0.3. We also find a possible dependence of the degreeof CO gas excitation on the efficiency of star-forming activity. Usingthe large velocity gradient (LVG) approximation to model the observeddata, we investigate the CO-to-H2 conversion factor X for theSLUGS sample. The results show that the mean value of X for the SLUGSsample is lower by a factor of 10 compared to the conventional valuederived for the Galaxy, if we assume the abundance of CO relative toH2, ZCO=10-4. For a subset of 12galaxies with H I maps, we derive a mean total face-on surface densityof H2+HI of about 42 Msolar pc-2 withinabout 2 kpc of the nucleus. This value is intermediate between that ingalaxies like our own and those with strong star formation.
| The IRAS Revised Bright Galaxy Sample
IRAS flux densities, redshifts, and infrared luminosities are reportedfor all sources identified in the IRAS Revised Bright Galaxy Sample(RBGS), a complete flux-limited survey of all extragalactic objects withtotal 60 μm flux density greater than 5.24 Jy, covering the entiresky surveyed by IRAS at Galactic latitudes |b|>5°. The RBGS includes629 objects, with median and mean sample redshifts of 0.0082 and 0.0126,respectively, and a maximum redshift of 0.0876. The RBGS supersedes theprevious two-part IRAS Bright Galaxy Samples(BGS1+BGS2), which were compiled before the final(Pass 3) calibration of the IRAS Level 1 Archive in 1990 May. The RBGSalso makes use of more accurate and consistent automated methods tomeasure the flux of objects with extended emission. The RBGS contains 39objects that were not present in the BGS1+BGS2,and 28 objects from the BGS1+BGS2 have beendropped from RBGS because their revised 60 μm flux densities are notgreater than 5.24 Jy. Comparison of revised flux measurements forsources in both surveys shows that most flux differences are in therange ~5%-25%, although some faint sources at 12 and 25 μm differ byas much as a factor of 2. Basic properties of the RBGS sources aresummarized, including estimated total infrared luminosities, as well asupdates to cross identifications with sources from optical galaxycatalogs established using the NASA/IPAC Extragalactic Database. Inaddition, an atlas of images from the Digitized Sky Survey with overlaysof the IRAS position uncertainty ellipse and annotated scale bars isprovided for ease in visualizing the optical morphology in context withthe angular and metric size of each object. The revised bolometricinfrared luminosity function, φ(Lir), forinfrared-bright galaxies in the local universe remains best fit by adouble power law, φ(L)~Lα, withα=-0.6(+/-0.1) and α=-2.2(+/-0.1) below and above the``characteristic'' infrared luminosityL*ir~1010.5Lsolar,respectively. A companion paper provides IRAS High Resolution (HIRES)processing of over 100 RBGS sources where improved spatial resolutionoften provides better IRAS source positions or allows for deconvolutionof close galaxy pairs.
| Spectroscopy of KISS Emission-Line Galaxy Candidates. I. MDM Observations
Spectroscopic observations for 351 emission-line galaxy candidates fromthe KPNO International Spectroscopic Survey (KISS) have been obtainedusing the MDM Observatory 2.4 m telescope on Kitt Peak. KISS is anongoing wide-field objective-prism survey for extragalacticemission-line objects, which has cataloged over 2200 emission-linegalaxy (ELG) candidates to date. Spectroscopic follow-up observationsare being carried out to study the characteristics of the surveyobjects. The observational data presented here include redshifts,reddening estimates, line equivalent widths, Hα line fluxes, andemission-line ratios. The galaxies have been classified based on theiremission-line characteristics. The procedure for selecting the ELGcandidates in KISS is found to be very reliable: 95% of the candidatesin this sample are verified to have emission lines. A comparison ofobjective-prism survey data-redshifts, Hα line fluxes, andequivalent widths-with the long-slit measurements shows good overallagreement.
| 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
| H I Properties of Low-Luminosity Star-forming Galaxies in the KPNO International Spectroscopic Survey
New H I observations are presented for a complete sample of 109low-luminosity star-forming galaxies taken from the KPNO InternationalSpectroscopic Survey (KISS), the first CCD-based wide-fieldobjective-prism survey for emission-line galaxies. This sample consistsof all star-forming galaxies with MB>-18.0 and cz<11,000km s-1 from the first Hα-selected survey list. Thegalaxies in this list lie within a 1.3d-wide strip centered onδ(B1950)=29°30', which spans the rangeα(B1950)=12h15m toα(B1950)=17h0m. Overall, 97 out of 109galaxies have been detected in H I. We confirm the weak trend ofincreasing gas richness with decreasing luminosity found by previousauthors. Gas richness is also shown to be weakly anticorrelated withmetallicity. The dependence of star formation rates (SFRs) and H I gasdepletion timescales on metallicity is examined. The mediansolar-metallicity-based SFR and gas depletion timescale are 0.16Msolar yr-1 and 5 Gyr, respectively. Correctionsfor variations in metallicity decreases SFRs by ~0.5 dex and increasesgas depletion timescales by an average of ~8 Gyr. The majority ofgalaxies in this sample still have large reservoirs of H I gas and,despite their large current star formation rates, could have formedstars in a quasi-continuous manner for a Hubble time. Finally, wepresent the first H I mass function for low-luminosity star-forminggalaxies and show that this subpopulation contributes 10%-15% of theoverall H I density in the local universe. We conclude that if the H Imass function of the universe does indeed have a steeply rising low-massslope, as suggested by previous authors, it is not due to the populationof low-luminosity star-forming galaxies. Comparison with the H I massfunction number densities from H I blind surveys in the range108 Msolar
| Bar Galaxies and Their Environments
The prints of the Palomar Sky Survey, luminosity classifications, andradial velocities were used to assign all northern Shapley-Ames galaxiesto either (1) field, (2) group, or (3) cluster environments. Thisinformation for 930 galaxies shows no evidence for a dependence of barfrequency on galaxy environment. This suggests that the formation of abar in a disk galaxy is mainly determined by the properties of theparent galaxy, rather than by the characteristics of its environment.
| Rotation curves and metallicity gradients from HII regions in spiral galaxies
In this paper we study long slit spectra in the region of Hαemission line of a sample of 111 spiral galaxies with recognizable andwell defined spiral morphology and with a well determined environmentalstatus, ranging from isolation to non-disruptive interaction withsatellites or companions. The form and properties of the rotation curvesare considered as a function of the isolation degree, morphological typeand luminosity. The line ratios are used to estimate the metallicity ofall the detected HII regions, thus producing a composite metallicityprofile for different types of spirals. We have found that isolatedgalaxies tend to be of later types and lower luminosity than theinteracting galaxies. The outer parts of the rotation curves of isolatedgalaxies tend to be flatter than in interacting galaxies, but they showsimilar relations between global parameters. The scatter of theTully-Fisher relation defined by isolated galaxies is significantlylower than that of interacting galaxies. The [NII]/Hα ratios, usedas a metallicity indicator, show a clear trend between Z andmorphological type, t, with earlier spirals showing higher ratios; thistrend is tighter when instead of t the gradient of the inner rotationcurve, G, is used; no trend is found with the change in interactionstatus. The Z-gradient of the disks depends on the type, being almostflat for early spirals, and increasing for later types. The[NII]/Hα ratios measured for disk HII regions of interactinggalaxies are higher than for normal/isolated objects, even if all thegalaxy families present similar distributions of Hα EquivalentWidth. Tables 3 and 4 and Figs. 6, 7 and 21 are only available inelectronic form at http://www.edpsciences.org. Table 5 is only availablein electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr(130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/393/389 Based on dataobtained Asiago/Ekar Observatory. Also based on observations made withINT operated on the island of La Palma by ING in the SpanishObservatorio del Roque de Los Muchachos of the Instituto deAstrofísica de Canarias.
| The Radio Galaxy Populations of Nearby Northern Abell Clusters
We report on the use of the NRAO VLA Sky Survey (NVSS) to identify radiogalaxies in 18 nearby Abell clusters. The listings extend from the coresof the clusters out to radii of 3 h-175 Mpc, whichcorresponds to 1.5 Abell radii and approximately 4 orders of magnitudein galaxy density. To create a truly useful catalog, we have collectedoptical spectra for nearly all of the galaxies lacking public velocitymeasurements. Consequently, we are able to discriminate between thoseradio galaxies seen in projection on the cluster and those that are inactuality cluster members. The resulting catalog consists of 329 clusterradio galaxies plus 138 galaxies deemed foreground or backgroundobjects, and new velocity measurements are reported for 273 of theseradio galaxies. The motivation for the catalog is the study of galaxyevolution in the cluster environment. The radio luminosity function is apowerful tool in the identification of active galaxies, as it isdominated by star-forming galaxies at intermediate luminosities andactive galactic nuclei (AGNs) at higher luminosities. The flux limit ofthe NVSS allows us to identify AGNs and star-forming galaxies down tostar formation rates less than 1 Msolar yr-1. Thissensitivity, coupled with the all-sky nature of the NVSS, allows us toproduce a catalog of considerable depth and breadth. In addition tothese data, we report detected infrared fluxes and upper limits obtainedfrom IRAS data. It is hoped that this database will prove useful in anumber of potential studies of the effect of environment on galaxyevolution. Based in part on observations obtained with the Apache PointObservatory 3.5 m telescope, which is owned and operated by theAstrophysical Research Consortium (ARC).
| Redshifts for 2410 Galaxies in the Century Survey Region
The Century Survey strip covers 102 deg2 within the limits8h5<=α<=16h5, 29.0d<=δ<=30.0d, equinoxB1950.0. The strip passes through the Corona Borealis supercluster andthe outer region of the Coma cluster. Within the Century Survey region,we have measured 2410 redshifts that constitute four overlappingcomplete redshift surveys: (1) 1728 galaxies with Kron-CousinsRph<=16.13 covering the entire strip, (2) 507 galaxieswith Rph<=16.4 in right ascension range8h32m<=α<=10h45m, equinox B1950.0, (3) 1251 galaxies withabsorption- and K-corrected RCCDc<=16.2 (where ``c''indicates ``corrected'') covering the right ascension range8h5<=α<=13h5, equinox B1950.0, and (4) 1255 galaxieswith absorption- and K-corrected VCCDc<=16.7 also coveringthe right ascension range 8h5<=α<=13h5, equinoxB1950.0. All these redshift samples are more than 98% complete to thespecified magnitude limit. We derived samples 1 and 2 from scans of thePOSS1 red (E) plates calibrated with CCD photometry. We derived samples3 and 4 from deep V and R CCD images covering the entire region. Weinclude coarse morphological types for all the galaxies in sample 1. Thedistribution of (V-R)CCD for each type correspondsappropriately with the classification. Work reported here is basedpartly on observations obtained at the Michigan-Dartmouth-MITObservatory.
| V- and R-band Galaxy Luminosity Functions and Low Surface Brightness Galaxies in the Century Survey
We use 64 deg2 of deep V and R CCD images to measure thelocal V- and R-band luminosity functions of galaxies. TheV0<16.7 and R0<16.2 redshift samples contain1255 and 1251 galaxies and are 98.1% and 98.2% complete, respectively.We apply k-corrections before the magnitude selection so that thecompleteness is to the same depth for all spectral types. The V and Rfaint-end slopes are surprisingly identical: α=-1.07+/-0.09.Representative Schechter function parameters for H0=100 are:M*R=-20.88+/-0.09,φ*R=0.016+/-0.003 Mpc-3 andM*V=-20.23+/-0.09,φ*V=0.020+/-0.003 Mpc-3. The V andR local luminosity densities,jR=(1.9+/-0.6)×108 Lsolar andjV=(2.2+/-0.7)×108 Lsolar, are inessential agreement with the recent 2 Degree Field Galaxy RedshiftSurvey and Sloan Digital Sky Survey determinations. All low surfacebrightness (LSB) galaxies fall in the large-scale structure delineatedby high surface brightness galaxies. The properties and surface numberdensity of our LSB galaxies are consistent with the LSB galaxy catalogof O'Neil, Bothun & Cornell, suggesting that our samples arecomplete for LSB galaxies to the magnitude limits. We measure colors,surface brightnesses, and luminosities for our samples, and find strongcorrelations among these galaxy properties. The color-surface brightnessrelation is(V-R)0=(-0.11+/-0.05)μR,0+(2.6+/-0.9).
| The KPNO International Spectroscopic Survey. II. Hα-selected Survey List 1
The KPNO International Spectroscopic Survey (KISS) is a newobjective-prism survey for extragalactic emission-line objects. Itcombines many of the features of previous slitless spectroscopic surveyswith the advantages of modern CCD detectors and is the first purelydigital objective-prism survey for emission-line galaxies. Here wepresent the first list of emission-line galaxy candidates selected fromour red spectral data, which cover the spectral range 6400 to 7200Å. In most cases, the detected emission line is Hα. Thecurrent survey list covers a 1°-wide strip located atδ=29°30' (B1950.0) and spanning the right ascension range12h15m to 17h0m. An area of62.2 deg2 is covered. A total of 1128 candidate emission-lineobjects have been selected for inclusion in the survey list (18.1deg-2). We tabulate accurate coordinates and photometry foreach source, as well as estimates of the redshift and emission-line fluxand equivalent width based on measurements of the digitalobjective-prism spectra. The properties of the KISS emission-linegalaxies are examined using the available observational data.
| 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.
| The SCUBA Local Universe Galaxy Survey - I. First measurements of the submillimetre luminosity and dust mass functions
This is the first of a series of papers presenting results from theSCUBA Local Universe Galaxy Survey (SLUGS), the first statistical surveyof the submillimetre properties of the local Universe. As the initialpart of this survey, we have used the SCUBA camera on the James ClerkMaxwell Telescope to observe 104 galaxies from the IRAS Bright GalaxySample. We present here the 850-μm flux measurements. The 60-, 100-,and 850-μm flux densities are well fitted by single-temperature dustspectral energy distributions, with the sample mean and standarddeviation for the best-fitting temperature beingTd=35.6+/-4.9K and for the dust emissivity indexβ=1.3+/-0.2. The dust temperature was found to correlate with60-μm luminosity. The low value of β may simply mean that thesegalaxies contain a significant amount of dust that is colder than thesetemperatures. We have estimated dust masses from the 850-μm fluxesand from the fitted temperature, although if a colder component ataround 20K is present (assuming a β of 2), then the estimated dustmasses are a factor of 1.5-3 too low. We have made the first directmeasurements of the submillimetre luminosity function (LF) and of thedust mass function. Unlike the IRAS 60-μm LF, these are well fittedby Schechter functions. The slope of the 850-μm LF at lowluminosities is steeper than -2, implying that the LF must flatten atluminosities lower than we probe here. We show that extrapolating the60-μm LF to 850μm using a single temperature and β does notreproduce the measured submillimetre LF. A population of `cold' galaxies(Td<25K) emitting strongly at submillimetre wavelengthswould have been excluded from the 60-μm-selected sample. If suchgalaxies do exist, then this estimate of the 850-μm flux is biased(it is underestimated). Whether such a population does exist is unknownat present. We correlate many of the global galaxy properties with theFIR/submillimetre properties. We find that there is a tendency for lessluminous galaxies to contain hotter dust and to have a greater starformation efficiency (cf. Young). The average gas-to-dust ratio for thesample is 581+/-43 (using both the atomic and molecular hydrogen), whichis significantly higher than the Galactic value of 160. We believe thatthis discrepancy is probably due to a `cold dust' component atTd<=20K in our galaxies. There is a surprisingly tightcorrelation between dust mass and the mass of molecular hydrogen,estimated from CO measurements, with an intrinsic scatter of ~=50percent.
| Multiwavelength Observations of Dusty Star Formation at Low and High Redshift
If high-redshift galaxies resemble rapidly star-forming galaxies in thelocal universe, most of the luminosity produced by their massive starswill have been absorbed by dust and reradiated as far-infrared photonsthat cannot be detected with existing facilities. This paper examineswhat can be learned about high-redshift star formation from the smallfraction of high-redshift galaxies' luminosities that is emitted ataccessible wavelengths. We first consider the most basic ingredient inthe analysis of high-redshift surveys: the estimation of star formationrates for detected galaxies. Standard techniques require an estimate ofthe bolometric luminosity produced by their massive stars. We review andquantify empirical correlations between bolometric luminosities producedby star formation and the UV, mid-IR, sub-mm, and radio luminosities ofgalaxies in the local universe. These correlations suggest thatobservations of high-redshift galaxies at any of these wavelengthsshould constrain their star formation rates to within ~0.2-0.3 dex. Weassemble the limited evidence that high-redshift galaxies obey theselocally calibrated correlations. The second part of the paper assesseswhether existing surveys have found the galaxies that host the majorityof star formation at high redshift even though they directly detect onlya small fraction of the luminosities of individual galaxies. We describethe characteristic luminosities and dust obscurations of galaxies atz~0, z~1, and z~3. After discussing the relationship between thehigh-redshift populations selected in surveys at different wavelengths,we calculate the contribution to the 850 μm background from each andargue that these known galaxy populations can together have produced theentire observed background. The available data show that a correlationbetween star formation rate and dust obscurationLbol,dust/LUV exists at low and high redshiftalike. The existence of this correlation plays a central role in themajor conclusion of this paper: most star formation at high redshiftoccurred in galaxies with moderate dust obscurations1<~Lbol,dust/LUV<~100 similar to those thathost the majority of star formation in the local universe and to thosethat are detected in UV-selected surveys.
| Investigations of the Local Supercluster velocity field. III. Tracing the backside infall with distance moduli from the direct Tully-Fisher relation
We have extended the discussion of Paper II (Ekholm et al.\cite{Ekholm99a}) to cover also the backside of the Local Supercluster(LSC) by using 96 galaxies within Theta <30degr from the adoptedcentre of LSC and with distance moduli from the direct B-bandTully-Fisher relation. In order to minimize the influence of theMalmquist bias we required log Vmax>2.1 and sigmaB_T<0.2mag. We found out that ifRVirgo<20 Mpc this sample fails to follow the expecteddynamical pattern from the Tolman-Bondi (TB) model. When we compared ourresults with the Virgo core galaxies given by Federspiel et al.(\cite{Federspiel98}) we were able to constrain the distance to Virgo:RVirgo=20-24 Mpc. When analyzing the TB-behaviour of thesample as seen from the origin of the metric as well as that withdistances from the extragalactic Cepheid PL-relation we found additionalsupport to the estimate RVirgo= 21 Mpc given in Paper II.Using a two-component mass-model we found a Virgo mass estimateMVirgo=(1.5 - 2)x Mvirial, whereMvirial=9.375*E14Msun forRVirgo= 21 Mpc. This estimate agrees with the conclusion inPaper I (Teerikorpi et al. \cite{Teerikorpi92}). Our results indicatethat the density distribution of luminous matter is shallower than thatof the total gravitating matter when q0<= 0.5. Thepreferred exponent in the density power law, alpha ~2.5, agrees withrecent theoretical work on the universal density profile of dark matterclustering in an Einstein-deSitter universe (Tittley & Couchman\cite{Tittley99}).
| 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.
| On the local radio luminosity function of galaxies. II. Environmental dependences among late-type galaxies
Using new extensive radio continuum surveys at 1.4 GHz (FIRST and NVSS),we derive the distribution of the radio/optical and radio/NIR luminosity(RLF) of late-type (Sa-Irr) galaxies (m_p<15.7) in 5 nearby clustersof galaxies: A262, Cancer, A1367, Coma and Virgo. With the aim ofdiscussing possible environmental dependences of the radio properties,we compare these results with those obtained for relatively isolatedobjects in the Coma supercluster. We find that the RLF of Cancer, A262and Virgo are consistent with that of isolated galaxies. Conversely weconfirm earlier claims that galaxies in A1367 and Coma have their radioemissivity enhanced by a factor ~ 5 with respect to isolated objects. Wediscuss this result in the framework of the dynamical pressure sufferedby galaxies in motion through the intra-cluster gas (ram-pressure). Wefind that the radio excess is statistically larger for galaxies in fasttransit motion. This is coherent with the idea that enhanced radiocontinuum activity is associated with magnetic field compression. TheX-ray luminosities and temperatures of Coma and A1367 imply that thesetwo clusters have significantly larger intracluster gas density than theremaining three studied ones, providing a clue for explaining the higherradio continuum luminosities of their galaxies. Multiple systems in theComa supercluster bridge (with projected separations smaller than 300kpc) have radio luminosities significantly larger than isolatedgalaxies. Table~1 is only available 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 Supernova Rate in Starburst Galaxies
We conducted an optical CCD search for supernovae in a sample of 142bright [m(B) <= 16 mag], nearby (z<=0.03) starburst galaxies overthe period 1988 December to 1991 June, to a limiting R-band magnitude of18. Five supernovae were found, in all cases outside the host galaxy'snucleus. We determine supernova rates (in supernova units or SNU) in theextranuclear regions to be 0.7 h^2 SNU for Type Ia, 0.7 h^2 SNU for TypeIb/c, and ~0.6 h^2 SNU for Type II, with large uncertainties but upperlimits of 2.2 h^2, 2.5 h^2, and 1.7 h^2 SNU, respectively. These ratesare similar to those measured in ``normal'' galaxies. We found noevidence for a supernova-induced brightening in any galactic nucleusand, with a few reasonable assumptions, can place upper limits of 9 h^2,12 h^2, and 7 h^2 SNU on the rates of unobscured supernovae Types Ia,Ib/c, and II, respectively, inside the nuclei.
| Bulge-Disk Decomposition of 659 Spiral and Lenticular Galaxy Brightness Profiles
We present one of the largest homogeneous sets of spiral and lenticulargalaxy brightness profile decompositions completed to date. The 659galaxies in our sample have been fitted with a de Vaucouleurs law forthe bulge component and an inner-truncated exponential for the diskcomponent. Of the 659 galaxies in the sample, 620 were successfullyfitted with the chosen fitting functions. The fits are generally welldefined, with more than 90% having rms deviations from the observedprofile of less than 0.35 mag. We find no correlations of fittingquality, as measured by these rms residuals, with either morphologicaltype or inclination. Similarly, the estimated errors of the fittedcoefficients show no significant trends with type or inclination. Thesedecompositions form a useful basis for the study of the lightdistributions of spiral and lenticular galaxies. The object base issufficiently large that well-defined samples of galaxies can be selectedfrom it.
| The Star Formation Properties of Disk Galaxies: Hα Imaging of Galaxies in the Coma Supercluster
We present integrated Hα measurements obtained from imagingobservations of 98 late-type galaxies, primarily selected in the Comasupercluster. These data, combined with Hα photometry from theliterature, include a magnitude-selected sample of spiral (Sa to Irr)galaxies belonging to the ``Great Wall'' complete up to m_p = 15.4, andthus composed of galaxies brighter than M_p = -18.8 (H_0 = 100 km s^-1Mpc^-1). The frequency distribution of the Hα equivalent width,determined for the first time from an optically complete sample, isapproximately Gaussian, peaking at EW ~ 25 Å. We find that, at thepresent limiting luminosity, the star formation properties of spiral +Irr galaxy members of the Coma and A1367 Clusters do not differsignificantly from those of the isolated ones belonging to the GreatWall. The present analysis confirms the well-known increase of thecurrent massive star formation rate (SFR) with Hubble type. Moreover,perhaps a more fundamental anticorrelation exists between the SFR andthe mass of disk galaxies: low-mass spirals and dwarf systems havepresent SFRs ~50 times higher than giant spirals. This result isconsistent with the idea that disk galaxies are coeval, evolving as``closed systems'' with exponentially declining SFR, and that the massof their progenitor protogalaxies is the principal parameter governingtheir evolution. Massive systems having high initial efficiency ofcollapse, or a short collapse timescale, have retained little gas tofeed the present epoch of star formation. These findings support theconclusions of Gavazzi & Scodeggio, who studied the color-massrelation of a local galaxy sample, and agree with the analysis by Cowieet al., who traced the star formation history of galaxies up to z >1. Based on observations made at the Observatorio AstronómicoNacional (OAN), San Pedro Mártir, B.C., of the UniversidadNacional Autónoma de México (UNAM).
| 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
| 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 Search for ``Dwarf'' Seyfert Nuclei. III. Spectroscopic Parameters and Properties of the Host Galaxies
We have completed an optical spectroscopic survey of the nuclear regions(r <~ 200 pc) of a large sample of nearby galaxies. Although the mainobjectives of the survey are to search for low-luminosity activegalactic nuclei and to quantify their luminosity function, the databasecan be used for a variety of other purposes. This paper presentsmeasurements of the spectroscopic parameters for the 418 emission-linenuclei, along with a compilation of the global properties of all 486galaxies in the survey. Stellar absorption generally poses a seriousobstacle to obtaining accurate measurement of emission lines in nearbygalactic nuclei. We describe a procedure for removing the starlight fromthe observed spectra in an efficient and objective manner. The mainparameters of the emission lines (intensity ratios, fluxes, profilewidths, and equivalent widths) are measured and tabulated, as areseveral stellar absorption-line and continuum indices useful forstudying the stellar population. Using standard nebular diagnostics, wedetermine the probable ionization mechanisms of the emission-lineobjects. The resulting spectral classifications provide extensiveinformation on the demographics of emission-line nuclei in the nearbyregions of the universe. This new catalog contains over 200 objectsshowing spectroscopic evidence for recent star formation and an equallylarge number of active galactic nuclei, including 46 that show broad Halpha emission. These samples will serve as the basis of future studiesof nuclear activity in nearby galaxies.
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