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Outflows in Infrared-Luminous Starbursts at z < 0.5. II. Analysis and Discussion1,
We have performed an absorption-line survey of outflowing gas in 78starburst-dominated, infrared-luminous galaxies. This is the largeststudy of superwinds at z<~3. Superwinds are found in almost allinfrared-luminous galaxies, and changes in detection rate with SFR-windsare found twice as often in ultraluminous infrared galaxies (ULIRGs) asin less-luminous galaxies-reflect different wind geometries. The maximumvelocities we measure are 600 km s-1, though most of theoutflowing gas has lower velocities (100-200 km s-1). (Onegalaxy has velocities exceeding 1000 km s-1.) Velocities inLINERs are higher than in H II galaxies, and outflowing ionized gasoften has higher velocities than the neutral gas. Wind properties(velocity, mass, momentum, and energy) scale with galaxy properties(SFR, luminosity, and galaxy mass), consistent with ram-pressure drivingof the wind. Wind properties increase strongly with increasing galacticmass, contrary to expectation. These correlations flatten at high SFR(>~10-100 Msolar yr-1), luminosities, andmasses. This saturation is due to a lack of gas remaining in the wind'spath, a common neutral gas terminal velocity, and/or a decrease in theefficiency of thermalization of the supernovae energy. It means thatmass entrainment efficiency, rather than remaining constant, declines ingalaxies with SFR>10 Msolar yr-1 andMK<-24. Half of our sample consists of ULIRGs, which hostas much as half of the star formation in the universe at z>~1. Thepowerful, ubiquitous winds we observe in these galaxies imply thatsuperwinds in massive galaxies at redshifts above unity play animportant role in the evolution of galaxies and the intergalacticmedium.Some of the observations reported here were obtained at the MMTObservatory, which is a joint facility of the Smithsonian Institutionand the University of Arizona.Some of the observations reported here were obtained at the Kitt PeakNational Observatory, National Optical Astronomy Observatory, which isoperated by the Association of Universities for Research in Astronomy,Inc. (AURA), under cooperative agreement with the National ScienceFoundation.
| Outflows in Infrared-Luminous Starbursts at z < 0.5. I. Sample, Na I D Spectra, and Profile Fitting1,
We have conducted a spectroscopic survey of 78 starburstinginfrared-luminous galaxies at redshifts up to z=0.5. We usemoderate-resolution spectroscopy of the Na I D interstellar absorptionfeature to directly probe the neutral phase of outflowing gas in thesegalaxies. Over half of our sample are ultraluminous infrared galaxiesthat are classified as starbursts; the rest have infrared luminositiesin the range log(LIR/Lsolar)=10.2-12.0. The sampleselection, observations, and data reduction are described here. Theabsorption-line spectra of each galaxy are presented. We also discussthe theory behind absorption-line fitting in the case of a partiallycovered, blended absorption doublet observed at moderate-to-highresolution, a topic neglected in the literature. A detailed analysis ofthese data is presented in a companion paper.Some of the observations reported here were obtained at the MMTObservatory, a joint facility of the Smithsonian Institution and theUniversity of Arizona.Some of the observations reported here were obtained at the Kitt PeakNational Observatory, National Optical Astronomy Observatory, which isoperated by the Association of Universities for Research in Astronomy,Inc. (AURA), under cooperative agreement with the National ScienceFoundation.
| The orientation parameters and rotation curves of 15 spiral galaxies
We analyzed ionized gas motion and disk orientation parameters for 15spiral galaxies. Their velocity fields were measured with the Hαemission line by using the Fabry-Perot interferometer at the 6 mtelescope of SAO RAS. Special attention is paid to the problem ofestimating the position angle of the major axis (PA0) and theinclination (i) of a disk, which strongly affect the derived circularrotation velocity. We discuss and compare different methods of obtainingthese parameters from kinematic and photometric observations, takinginto account the presence of regular velocity (brightness) perturbationscaused by spiral density waves. It is shown that the commonly usedmethod of tilted rings may lead to systematic errors in the estimationof orientation parameters (and hence of circular velocity) being appliedto galaxies with an ordered spiral structure. Instead we recommend usingan assumption of constancy of i and PA0 along a radius, toestimate these parameters. For each galaxy of our sample we presentmonochromatic Hα- and continuum maps, velocity fields of ionizedgas, and the mean rotation curves in the frame of a model of purecircular gas motion. Significant deviations from circular motion withamplitudes of several tens of km s-1 (or higher) are found inalmost all galaxies. The character and possible nature of thenon-circular motion are briefly discussed.Based on observations collected with the 6 m telescope of the SpecialAstrophysical Observatory (SAO) of the Russian Academy of Sciences(RAS), operated under the financial support of the Science Department ofRussia (registration number 01-43).Section 4 and Figs. 6-19 are only avalaible in electronic form athttp://www.edpsciences.org
| Star formation, massive stars, and super star clusters in nearby galaxies
The Square Kilometer Array (SKA) will enable studies of star formationin nearby galaxies with a level of detail never before possible outsideof the Milky Way. Because the earliest stages of stellar evolution areoften inaccessible at optical and near-infrared wavelengths, highspatial resolution radio observations are necessary to exploreextragalactic star formation. The SKA will have the sensitivity todetect individual ultracompact HII regions out to the distance of nearly50 Mpc, allowing us to study their spatial distributions, morphologies,and populations statistics in a wide range of environments. Radioobservations of Wolf-Rayet stars outside of the Milky Way will also bepossible for the first time, greatly expanding the range of conditionsin which their mass loss rates can be determined from free-freeemission. On a vastly larger scale, natal of super star clusters will beaccessible to the SKA out to redshifts of nearly z 0.1. Theunprecedented sensitivity of radio observations with the SKA will alsoplace tight constraints on the star formation rates as low as1Mȯ yr‑1 in galaxies out to a redshiftof z 1 by directly measuring the thermal radio flux densitywithout assumptions about a galaxy’s magnetic field strength,cosmic ray production rate, or extinction.
| On the alignment between binary spiral galaxies
We show some significance against the null hypothesis of randominteractions of binary spiral galaxies, and in favour of the alternativethat more interactions than expected occur for axes either nearlyparallel (spins being parallel or anti-parallel) or nearly orthogonal.We discuss this in the context of similar prior studies, using adifferent statistical focus in such a way that we are able toincorporate additional data.
| 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.
| 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.
| 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.
| An Hα survey aiming at the detection of extraplanar diffuse ionized gas in halos of edge-on spiral galaxies. I. How common are gaseous halos among non-starburst galaxies?
In a series of two papers we present results of a new Hα imagingsurvey, aiming at the detection of extraplanar diffuse ionized gas inhalos of late-type spiral galaxies. We have investigated a sample of 74nearby edge-on spirals, covering the northern and southern hemisphere.In 30 galaxies we detected extraplanar diffuse emission at meandistances of |z| ~ 1-2 kpc. Individual filaments can be traced out to|z|<=6 kpc in a few cases. We find a good correlation between the FIRflux ratio (S60/S100) and the SFR per unit area(LFIR/D225), based on thedetections/non-detections. This is actually valid for starburst, normaland for quiescent galaxies. A minimal SFR per unit area for the lowestS60/S100 values, at which extended emission hasbeen detected, was derived, which amounts to dotEA25thres = (3.2+/-0.5)*E40ergs-1 kpc-2. There are galaxies where extraplanaremission was detected at smaller values ofLFIR/D225, however, only in combinationwith a significantly enhanced dust temperature. The results corroboratethe general view that the gaseous halos are a direct consequence of SFactivity in the underlying galactic disk.Based on observations collected at the European Southern Observatory,Chile (ESO No. 63.N-0070, ESO No. 64.N-0034, ESO No. 65.N.-0002).
| 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.
| Local velocity field from sosie galaxies. I. The Peebles' model
Pratton et al. (1997) showed that the velocity field around clusterscould generate an apparent distortion that appears as tangentialstructures or radial filaments. In the present paper we determine theparameters of the Peebles' model (1976) describing infall of galaxiesonto clusters with the aim of testing quantitatively the amplitude ofthis distortion. The distances are determined from the concept of sosiegalaxies (Paturel 1984) using 21 calibrators for which the distanceswere recently calculated from two independent Cepheid calibrations. Weuse both B and I-band magnitudes. The Spaenhauer diagram method is usedto correct for the Malmquist bias. We give the equations for theconstruction of this diagram. We analyze the apparent Hubble constant indifferent regions around Virgo and obtain simultaneously the Local Groupinfall and the unperturbed Hubble constant. We found:[VLG-infall = 208 ± 9 km s-1] [\log H =1.82 ± 0.04 (H ≈ 66 ± 6 km s-1Mpc-1).] The front side and backside infalls can be seenaround Virgo and Fornax. In the direction of Virgo the comparison ismade with the Peebles' model. We obtain: [vinfall} =CVirgo/r0.9 ± 0.2] withCVirgo=2800 for Virgo and CFornax=1350 for Fornax,with the adopted units (km s-1 and Mpc). We obtain thefollowing mean distance moduli: [μVirgo=31.3 ± 0.2(r=18 Mpc )] [μFornax=31.7 ± 0.3 (r=22 Mpc). ] Allthese quantities form an accurate and coherent system. Full Table 2 isonly available in electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/393/57
| Compact groups in the UZC galaxy sample
Applying an automatic neighbour search algorithm to the 3D UZC galaxycatalogue (Falco et al. \cite{Falco}) we have identified 291 compactgroups (CGs) with radial velocity between 1000 and 10 000 kms-1. The sample is analysed to investigate whether Tripletsdisplay kinematical and morphological characteristics similar to higherorder CGs (Multiplets). It is found that Triplets constitute lowvelocity dispersion structures, have a gas-rich galaxy population andare typically retrieved in sparse environments. Conversely Multipletsshow higher velocity dispersion, include few gas-rich members and aregenerally embedded structures. Evidence hence emerges indicating thatTriplets and Multiplets, though sharing a common scale, correspond todifferent galaxy systems. Triplets are typically field structures whilstMultiplets are mainly subclumps (either temporarily projected orcollapsing) within larger structures. Simulations show that selectioneffects can only partially account for differences, but significantcontamination of Triplets by field galaxy interlopers could eventuallyinduce the observed dependences on multiplicity. Tables 1 and 2 are onlyavailable in electronic at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.125.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/391/35
| Combined Color Indices and Photometric Structures of the Galaxies NGC 834 and NGC 1134
Surface BVRI photometry is presented for two spiral galaxies with acomplex photometric structure: NGC 834 and NGC 1134. We propose tointroduce the combined color indices QBVI and QVRIto investigate the photometric structure of the galaxies. These colorindices depend only slightly on selective absorption, which allows themto be used to study the photometric structure of "dusty" galaxies.Evolutionary stellar-population models show that QBVI is mostsensitive to the presence of blue stars, while QVRI dependson local H_alpha equivalent width. A ring with active star formationmanifests itself on the QBVI map for NGC 834 at a distance of15 arcsec from its center, and a spiral structure shows up on theQVRI map for NGC 1134 in its inner region. TheQBVI-QVRI diagram can provide information aboutthe current stage of a star's formation in various galactic regions. Acomparison of the color indices for the galaxies with their model valuesallows us to estimate the color excesses and extinction in variousgalactic regions.
| 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.
| Absorption-Line Probes of Gas and Dust in Galactic Superwinds
We have obtained moderate resolution (R=few thousand) spectra of the NaI λλ5890, 5896 (Na D) absorption line in a sample of 32far-IR-bright starburst galaxies. In 18 cases, the Na D line in thenucleus is produced primarily by interstellar gas, while cool starscontribute significantly in the others. In 12 of the 18``interstellar-dominated'' cases the Na D line is blueshifted by over100 km s-1 relative to the galaxy systemic velocity (the``outflow sources''), while no case shows a net redshift of more than100 km s-1. The absorption-line profiles in these outflowsources span the range from near the galaxy systemic velocity to amaximum blueshift of ~400-600 km s-1. The outflow sources aregalaxies systematically viewed more nearly face-on than the others. Wetherefore argue that the absorbing material consists of ambientinterstellar material that has been entrained and accelerated along theminor axis of the galaxy by a hot starburst-driven superwind. The Na Dlines are optically thick, but indirect arguments imply total hydrogencolumn densities of NH~few×1021cm-2. This implies that the superwind is expelling matter ata rate comparable to the star formation rate. This outflowing materialis evidently very dusty: we find a strong correlation between the depthof the Na D profile and the line-of-sight reddening. Typical impliedvalues are E(B-V)=0.3-1 over regions several-to-10 kpc in size. Webriefly consider some of the potential implications of theseobservations. The estimated terminal velocities of superwinds inferredfrom the present data and extant X-ray data are typically 400-800km-1, are independent of the galaxy rotation speed, and arecomparable to (substantially exceed) the escape velocities forL* (dwarf) galaxies. The resulting selective loss of metalsfrom shallower potential wells can establish the mass-metallicityrelation in spheroids, produce the observed metallicity in theintracluster medium, and enrich a general IGM to of order10-1 solar metallicity. If the outflowing dust grains cansurvive their journey into the IGM, their effect on observations ofcosmologically distant objects would be significant.
| 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.
| 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
| 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 Mass-to-Light Ratio of Binary Galaxies
We report on the mass-to-light ratio determination based on a newlyselected binary galaxy sample, which includes a large number of pairswhose separations exceed a few hundred kpc. The probabilitydistributions of the projected separation and the velocity differencehave been calculated considering the contamination of optical pairs, andthe mass-to-light (M/L) ratio has been determined based on the maximumlikelihood method. The best estimate of the M/L in the B band for 57pairs is found to be 28-36 depending on the orbital parameters and thedistribution of optical pairs (solar unit: H_0=50 km s^-1 Mpc^-1). Thebest estimate of the M/L for 30 pure spiral pairs is found to be 12-16.These results are relatively smaller than those obtained in previousstudies but are consistent with each other within the errors. Althoughthe number of pairs with large separation is significantly increasedcompared with previous samples, the M/L does not show any tendency ofincrease but is found to be almost independent of the separation ofpairs beyond 100 kpc. The constancy of the M/L beyond 100 kpc mayindicate that the typical halo size of spiral galaxies is less than ~100kpc.
| 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.
| Flat rotation curves of galaxies are left in the past.
Not Available
| Very Wide Galaxy Pairs of the Northern and Southern Sky
We present highly accurate observations of the 21 cm line of hydrogen ingalaxies made at the Arecibo and Parkes Observatories. The galaxiesobserved have been identified, through rigorous selection criteriaapplied to the CfA and SSRS catalogs, as being members of pairs withprojected separations of up to 1.5 Mpc (H0 = 75 km s-1 Mpc-1). Theseobservations form the completion of the Chengalur-Nordgren galaxy pairsample with data previously published by Chengalur, Nordgren andcolleagues. The new selection criteria used in this paper are anextension to larger projected separations of the criteria usedpreviously. Forty-nine new galaxies are observed, while H I is detectedin 41 of them. With the addition of these galaxies, the completed samplehas highly accurate H I velocities for a total of 219 galaxies.
| Toward a Unified Model for the ``Diffuse Ionized Medium'' in Normal and Starburst Galaxies
The ``diffuse ionized medium'' (DIM) makes up a significant fraction ofthe mass and ionization requirements of the interstellar medium of theMilky Way and is now known to be an energetically significant componentin most normal star-forming galaxies. Observations of the ionized gas instarburst galaxies have revealed the presence of gas with strikingsimilarities to the DIM in normal galaxies: relatively low surfacebrightness and strong emission from low-ionization forbidden lines like[S II] lambdalambda6716, 6731. In this paper we analyze Hα imagesand long-slit spectra of samples of normal and starburst galaxies tobetter understand the nature of this diffuse, low surface brightnessgas. We find that in both samples there is a strong inverse correlationbetween the Hα surface brightness (Sigma_Hα) and the [SII]/Hα line ratio at a given location in the galaxy. However, thecorrelation for the starbursts is offset brightward by an order ofmagnitude in Hα surface brightness at a given line ratio. Incontrast, we find that all the galaxies (starburst and normal alike)define a universal relation between line ratio and the relative Hαsurface brightness (Sigma_Hα/Sigma_e, where Sigma_e is the meanHα surface brightness within the galaxy half-light radius). Weshow that such a universal correlation is a natural outcome of a modelin which the DIM is photoionized gas that has a characteristic thermalpressure (P) that is proportional to the mean rate of star formation perunit area in the galaxy (Sigma_SFR). Good quantitative agreement withthe data follows if we require the constant of proportionality to beconsistent with the values of P and Sigma_SFR in the local disk of theMilky Way. Such a scaling between P and Sigma_SFR may arise eitherbecause feedback from massive stars heats the ISM or because Sigma_SFRis determined (or limited) by the mean gas pressure.
| Groups of galaxies. III. Some empirical characteristics.
Not Available
| Catalogue of HI maps of galaxies. I.
A catalogue is presented of galaxies having large-scale observations inthe HI line. This catalogue collects from the literature the informationthat characterizes the observations in the 21-cm line and the way thatthese data were presented by means of maps, graphics and tables, forshowing the distribution and kinematics of the gas. It containsfurthermore a measure of the HI extension that is detected at the levelof the maximum sensitivity reached in the observations. This catalogueis intended as a guide for references on the HI maps published in theliterature from 1953 to 1995 and is the basis for the analysis of thedata presented in Paper II. The catalogue is only available inelectronic form at the CDS via anonymous ftp 130.79.128.5 orhttp://cdsweb.u-strasbg.fr/Abstract.html
| 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
| The Nature of Starburst Galaxies
Utilizing a large sample of infrared-selected starburst galaxies havingoptical images and long-slit spectra, we explore the interrelationshipsbetween the properties of starbursts and relate these properties tothose of the "host" galaxy. We find that the half-light radius of theHα-emitting region (r_e,Hα_) enters into severalcorrelations that suggest it is physically related to the actualstarburst radius. Most suggestively, the effective IR surface brightness(L_IR_/πr^2^_e,Hα_) correlates strongly with the far-IR colortemperature. This can be reproduced roughly with an idealized model of asurrounding dust screen whose far-IR emissivity is determined by thelocal energy density of UV starburst light. Typical values forr_e,Hα_ are a few hundred pc to a few kpc (with the Hαemission being significantly more compact than the red starlight). Thisconfirms the "circumnuclear" scales of typical starbursts. We show alsothat starbursts seem to obey a limiting IR surface brightness of about10^11^L_sun_ kpc^2^, corresponding to a maximum star formation rate ofabout 20 M_sun_ yr^-1^ kpc^2^ for a normal initial mass function. Weargue that this upper limit suggests that starbursts are self-regulatingin some way. We show that most of these galaxies have relatively normal,symmetric rotation curves. This implies that the galactic disk need notsuffer severe dynamical damage in order to "fuel" a typical starburst.We show also that the starbursts occur preferentially in the innerregion of solid-body rotation. This may reflect both bar-driven inflowof gas to the region between the inner Lindblad resonances and thedominance of gravitational instability over tidal shear in this region.Most of the starbursts reside in galaxies with rotation speeds of120-200 km s^-1^ (compared to 220 km s^-1^ for a fiducial L^*^ galaxylike the Milky Way). The lack of a correlation between galaxy rotationspeed and starburst luminosity means that even relatively modestgalaxies (masses~10% of the Milky Way) can host powerful starbursts. Weargue on the basis of causality that the internal velocity dispersion ina starburst sets an upper limit to the star formation rate. The mostextreme starbursts approach this limit, but most are well below.Finally, we show that the relative narrowness of the nuclear emissionlines in starbursts (relative to the galaxy rotation speed) arisesbecause the gas in the nuclear "bin" usually does not sample fully thesolid-body part of the rotation curve. The narrow lines do notnecessarily imply that the starburst is not in dynamical equilibrium.
| Large-Scale Outflows in Edge-on Seyfert Galaxies. II. Kiloparsec-Scale Radio Continuum Emission
We present deep images of the kiloparsec-scale radio continuum emissionin 14 edge-on galaxies (10 Seyfert and four starburst galaxies).Observations were taken with the VLA at 4.9 GHz (6 cm). The Seyfertgalaxies were selected from a distance-limited sample of 22 objects(defined in the first paper in this series). The starburst galaxies wereselected to be well matched to the Seyferts in radio power, recessionalvelocity, and galaxy disk inclination angle. All four starburst galaxieshave a very bright disk component, and one (NGC 3044) has a radio halothat extends several kiloparsecs out of the galaxy plane. Six of the 10Seyferts observed have large-scale (radial extent > 1 kpc) radiostructures extending outward from the nuclear region, indicating thatlarge-scale outflows are quite common in Seyferts. Large-scale radiosources in Seyferts are similar in radio power and radial extent toradio halos in edge-on starburst galaxies, but their morphologies do notresemble spherical halos observed in starburst galaxies. The sourceshave diffuse morphologies, but, in general, they are oriented at skewedangles with respect to the galaxy minor axes. This result is most easilyunderstood if the outflows are AGN-driven jets that are somehow divertedaway from the galaxy disk on scales > 1 kpc. Starburst-driven winds,however, cannot be ruled out. More observational work is needed todetermine whether massive star formation is present at high enough ratesto drive galactic winds out to kiloparsec scales in Seyfert galaxies.
| Ionized Gas in the Halos of Edge-on Starburst Galaxies: Evidence for Supernova-driven Superwinds
Supernova-driven galactic winds ("superwinds") have been invoked toexplain many aspects of galaxy formation and evolution. Such windsshould arise when the supernova rate is high enough to create a cavityof very hot shock-heated gas within a galaxy. This gas can then expandoutward as a high-speed wind that can accelerate and heat ambientinterstellar or circum-galactic gas causing it to emit optical lineradiation and/or thermal X-rays. Theory suggests that such winds shouldbe common in starburst galaxies and that the nature of the winds shoulddepend on the star formation rate and distribution. In order tosystematize our observational understanding of superwinds (determinetheir incidence rate and the dependence of their properties on the starformation that drives them) and to make quantitative comparisons withthe theory of superwinds, we have analyzed data from an opticalspectroscopic and narrow-band imaging survey of an infrared flux-limited(S_60 microns_ >= 5.4 Jy) sample of about 50 IR-warm (S_60microns_/S_100 microns_ > 0.4), starburst galaxies whose stellardisks are viewed nearly edge-on (b/a ~> 2). This sample containsgalaxies with infrared luminosities from ~10^10^-10^12^ L_sun_ andallows us to determine the properties of superwinds over a wide range ofstar formation rates. We have found that extraplanar emission-line gasis a very common feature of these edge-on, IR-bright galaxies and theproperties of the extended emission-line gas are qualitatively andquantitatively consistent with the superwind theory. We can summarizethese properties as morphological, ionization, dynamical, and physical.1. Morphological properties.-Extraplanar filamentary and shell-likeemission-line morphologies on scales of hundreds of parsecs to 10 kpcare common, there is a general "excess" of line emission along the minoraxis, the minor axis emission-line "excess" correlates with "IRactivity," and the minor axis emission-line "excess" also correlateswith the relative compactness of the Hα emission. 2. Ionizationproperties.-Line ratios become more "shocklike" (high ratios of [N II]λ6583/Hα, [S II] λλ6716, 6731/Hα, and[O I] λ6300/Hα) at more extreme IR properties, the most"shocklike" line ratios occur far out along the minor axis, "shocklike"line ratios corresponds to broad emission lines, and the most extremeline ratios correspond to the most extreme IR properties, especially forthe emission-line gas farthest out along the minor axis. 3. Dynamicalproperties.-Lines are broader along the minor axis than along the majoraxis, line widths correlate with the "IR activity," line widthscorrelate with line ratios, line widths do not correlate with rotationspeed, minor axis shear (a measure of the systematic velocity changealong the minor axis) correlates with "IR activity," minor axis shearcorrelates with axial ratio and implies that a face-on galaxy would havean outflow/inflow speed of 170_-80_^+150^ km s^-1^, and the starburstsshow statistically blueward line profile asymmetries. 4. Physicalproperties.-Pressures in the nuclei of these galaxies are 3 orders ofmagnitude higher than the ambient pressure in the interstellar medium ofour galaxy, and the pressure falls systematically with radius. Whilenone of these results are in themselves proof of the superwind model, webelieve that when the results are taken as a whole, the superwindhypothesis is very successful in explaining what we have observed. Inaddition, these results have implications for galaxy evolution and thenature of the intergalactic medium. Those galaxies with the bestevidence for driving superwinds are those with large IR luminosities(L_IR_ ~> 10^44^ ergs s^-1^), large IR excesses (L_IR_/L_OPT_ ~>2), and warm far-IR colors (S_60 microns_/S_100 microns_ ~> 0.5).Integrating over the local far-IR luminosity function for galaxiesmeeting the above criteria, multiplying by the age of the universe, andthen dividing by the local space density of galaxies implies thatsuperwinds have carried out ~5 x 10^8^ M_sun_ in metals and 10^59^ ergsin kinetic plus thermal energy per average (Schecter L^*^) galaxy overthe history of the universe. We note that these two quantities areapproximately equal to the mass of metals contained inside an averagegalaxy and the gravitational binding energy of an average galaxy,respectively. Even with the conservative assumptions of this calculation(we have neglected that star formation rates were presumably higher inthe early universe), it is obvious that superwinds may have a majorimpact on the evolution of individual galaxies and the intergalacticmedium by injecting mass, metals, and kinetic energy into the galactichalo and potentially the intergalactic medium.
| Dust and CO emission in normal spirals. I. The data.
We present 1300μm continuum observations and measurements of the CO(1-0) and (2-1) emission from the inner regions of 98 normal galaxies.The spatial resolution ranges from 11" to 45". The sources come from acomplete FIR selected sample of 138 inactive spirals with an opticaldiameter D_25_<=180".
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