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Mid-Infrared Spectra of Classical AGNs Observed with the Spitzer Space Telescope
Full low-resolution (65
| Star Formation History and Extinction in the Central Kiloparsec of M82-like Starbursts
We report on the star formation histories and extinction in the centralkiloparsec region of a sample of starburst galaxies that have similarfar-infrared (FIR), 10 μm, and K-band luminosities as those of thearchetype starburst M82. Our study is based on new optical spectra andpreviously published K-band photometric data, both sampling the samearea around the nucleus. Model starburst spectra were synthesized as acombination of stellar populations of distinct ages formed over theHubble time and were fitted to the observed optical spectra and K-bandflux. The model is able to reproduce simultaneously the equivalentwidths of emission and absorption lines, the continuum fluxes between3500 and 7000 Å, and the K-band and FIR flux. A good fit requiresa minimum of three populations: (1) a young population of age <=8Myr, with its corresponding nebular emission, (2) an intermediate-agepopulation (age <500 Myr), and (3) an old population that forms partof the underlying disk or/and bulge population. The birthrate parameter,which is defined as the ratio of the current star formation rate to theaverage past rate, is found to be in the range 1-12. The contribution ofthe old population to the K-band luminosity depends on the birthrateparameter and remains above 60% in the majority of the sample galaxies.Even in the blue band, the intermediate-age and old populationscontribute more than 40% of the total flux in all the cases. Arelatively high contribution from the old stars to the K-band nuclearflux is also apparent from the strength of the 4000 Å break andthe Ca II K line. The extinction of the old population is found to bearound half that of the young population. The contribution to thecontinuum from the relatively old stars has the effect of diluting theemission equivalent widths below the values expected for young bursts.The mean dilution factors are found to be 5 and 3 for the Hα andHβ lines, respectively.
| Deprojecting spiral galaxies using Fourier analysis. Application to the Ohio sample
We use two new methods developed recently (Barberàet al.\cite{bar03}, A&A, 415, 849), as well as information obtained fromthe literature, to calculate the orientation parameters of the spiralgalaxies in the Ohio State University Bright Galaxy Survey. We comparethe results of these methods with data from the literature, and find ingeneral good agreement. We provide a homogeneous set of mean orientationparameters which can be used to approximately deproject the disks of thegalaxies and facilitate a number of statistical studies of galaxyproperties.Table 1 is only available in electronic form at the CDS via anonymousftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/421/595
| The PDS versus Markarian starburst galaxies: comparing strong and weak IRAS emitter at 12 and 25 μm in the nearby Universe
The characteristics of the starburst galaxies from the Pico dos Diassurvey (PDS) are compared with those of the nearby ultraviolet (UV)bright Markarian starburst galaxies, having the same limit in redshift(vh < 7500 km s-1) and absolute B magnitude(MB < -18). An important difference is found: theMarkarian galaxies are generally undetected at 12 and 25 μm in IRAS.This is consistent with the UV excess shown by these galaxies andsuggests that the youngest star-forming regions dominating thesegalaxies are relatively free of dust.The far-infrared selection criteria for the PDS are shown to introduce astrong bias towards massive (luminous) and large size late-type spiralgalaxies. This is contrary to the Markarian galaxies, which are found tobe remarkably rich in smaller size early-type galaxies. These resultssuggest that only late-type spirals with a large and massive disc arestrong emitters at 12 and 25 μm in IRAS in the nearby Universe.The Markarian and PDS starburst galaxies are shown to share the sameenvironment. This rules out an explanation of the differences observedin terms of external parameters. These differences may be explained byassuming two different levels of evolution, the Markarian being lessevolved than the PDS galaxies. This interpretation is fully consistentwith the disc formation hypothesis proposed by Coziol et al. to explainthe special properties of the Markarian SBNG.
| 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).
| 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
| 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.
| 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.
| Compact Radio Emission from Warm Infrared Galaxies
In this paper, we present a comparison between the optical spectroscopicdata and the incidence of compact radio emission for a sample of 60 warminfrared galaxies. We find that 80% of optically classified activegalactic nucleus (AGN)-type galaxies contain compact radio sources,while 37% of optically classified starburst galaxies contain compactradio sources. The compact radio luminosity shows a bimodaldistribution, indicating two populations in our sample. The majority ofthe higher radio luminosity class (L>104Lsolar) are AGNs, while the majority of the lower radioluminosity class (L<104 Lsolar) are starbursts.The compact radio emission in the starburst galaxies may be due toeither obscured AGNs or complexes of extremely luminous supernovae suchas that seen in Arp 220. The incidence of optically classified AGNsincreases with increasing far-infrared (FIR) luminosity. Using FIRcolor-color diagrams, we find that globally the energetics of 92% of thegalaxies in our sample are dominated by starburst activity, including60% of galaxies that we find to contain AGNs on the basis of theiroptical classification. The remainder are energetically dominated bytheir AGNs in the infrared. For starburst galaxies, electron densityincreases with dust temperature, consistent with the merger model forinfrared galaxies.
| Obtaining Galaxy Masses Using Stellar Absorption and [O II] Emission-Line Diagnostics in Late-Type Galaxies
The [O II] λ3727 emission lines and absorption features fromstellar Balmer and Ca H and K lines are the most accessible kinematicdiagnostics in galaxies at z~1. We investigate the kinematics of 22local late-type galaxies using these spectral features, and we comparethe results with 21 cm neutral hydrogen spectra in order to assess theutility of each diagnostic for measuring galaxy masses. In order tosimulate data at high redshift, where only one-dimensional velocityprofiles are normally available, we study spatially integrated, as wellas spatially resolved, spectra. Although the studied galaxies span awide range of morphological types, inclinations, and star formationrates, we find that the gaseous and stellar kinematic tracers yieldcomparable kinematic line widths and systemic velocities. The [O II] andH I line widths correlate most strongly, showing an intrinsic dispersionof ~20 km s-1, or ~10% for a typical galaxy with a kinematicwidth of 200 km s-1. In a few extreme cases, the [O II] linewidths underestimate the neutral hydrogen width by 50%. Reliablevelocity widths can also be obtained from the stellar Balmer and Ca Hand K absorption lines, even for some of the very late type galaxiesthat have strong emission lines. The intrinsic dispersion is <=10%between the stellar absorption and H I line widths. We provide aprescription for using these strong stellar absorption and [O II]emission features to measure the kinematics, and thus masses, ofgalaxies in the distant universe.
| 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
| The FIR-radio correlation of Wolf-Rayet galaxies and the role of star formation in LINERs
We find that a preliminary classification of LINERs' energetics may bemade in terms of the FIR-radio correlation of Wolf-Rayet galaxies. TheAGN- or starburst-supported LINERs can be distinguished by theirFIR-to-radio ratio, Qequiv L(1.4GHz)/ L(60mum )> or <0.01. It isinteresting to note that almost all the LINERs with inner rings might bestarburst-supported, indicating reduced AGN activities compared withthose of the AGN-supported ones. We also find that a shock-heating phasefor the warm dust component might be important for some starbursts atthe burst age of >= 107 yr, with Q<0.001.
| 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}).
| The role of star formation in liners.
Not Available
| The QDOT all-sky IRAS galaxy redshift survey
We describe the construction of the QDOT survey, which is publiclyavailable from an anonymous FTP account. The catalogue consists ofinfrared properties and redshifts of an all-sky sample of 2387 IRASgalaxies brighter than the IRAS PSC 60-μm completeness limit(S_60>0.6Jy), sparsely sampled at a rate of one-in-six. At |b|>10deg, after removing a small number of Galactic sources, the redshiftcompleteness is better than 98per cent (2086/2127). New redshifts for1401 IRAS sources were obtained to complete the catalogue; themeasurement and reduction of these are described, and the new redshiftstabulated here. We also tabulate all sources at |b|>10 deg with noredshift so far, and sources with conflicting alternative redshiftseither from our own work, or from published velocities. A list of 95ultraluminous galaxies (i.e. with L_60μm>10^12 L_solar) is alsoprovided. Of these, ~20per cent are AGN of some kind; the broad-lineobjects typically show strong Feii emission. Since the publication ofthe first QDOT papers, there have been several hundred velocity changes:some velocities are new, some QDOT velocities have been replaced by moreaccurate values, and some errors have been corrected. We also present anew analysis of the accuracy and linearity of IRAS 60-μm fluxes. Wefind that the flux uncertainties are well described by a combination of0.05-Jy fixed size uncertainty and 8per cent fractional uncertainty.This is not enough to cause the large Malmquist-type errors in the rateof evolution postulated by Fisher et al. We do, however, find marginalevidence for non-linearity in the PSC 60-μm flux scale, in the sensethat faint sources may have fluxes overestimated by about 5per centcompared with bright sources. We update some of the previous scientificanalyses to assess the changes. The main new results are as follows. (1)The luminosity function is very well determined overall but is uncertainby a factor of several at the very highest luminosities(L_60μm>5x10^12L_solar), as this is where the remainingunidentified objects are almost certainly concentrated. (2) Thebest-fitting rate of evolution is somewhat lower than our previousestimate; expressed as pure density evolution with density varying as(1+z)^p, we find p=5.6+/-2.3. Making a rough correction for the possible(but very uncertain) non-linearity of fluxes, we find p=4.5+/-2.3. (3)The dipole amplitude decreases a little, and the implied value of thedensity parameter, assuming that IRAS galaxies trace the mass, isΩ=0.9(+0.45, -0.25). (4) Finally, the estimate of density varianceon large scales changes negligibly, still indicating a significantdiscrepancy from the predictions of simple cold dark matter cosmogonies.
| A Near-IR Spectral Atlas of IR-Selected Nearby Spirals
We have secured long-slit spectra with R~ 440, covering the K, H and Jbands, of 28, 26 and 13 nearby galaxies respectively. The target listcomprises complete samples, flux-limited at 25 μm, of `normal'(control) galaxies (undistorted morphology, normal IRAS colours),`normal starbursts' (undistorted morphology, starburst IRAS colours),`interacting/merger starbursts' (multiple/ disturbed morphology,starburst IRAS colours), Seyferts 1 and 2 and two low-metallicitystar-forming systems. LINERs were included but were not separatelyselected. We here describe this data set, which is to be made publiclyavailable as an atlas of spectra, and remark on a few results alreadyapparent in the partially-reduced data.
| An Infrared Search for Extinguished Supernovae in Starburst Galaxies
IR and radio-band observations of heavily extinguished regions instarburst galaxies suggest a high supernova (SN) rate associated withsuch regions. Optically measured SN rates may therefore underestimatethe total SN rate by factors of up to 10, as a result of the very highextinction (A_B~10-20 mag) to core-collapse SNe in starburst regions.The IR/radio SN rates come from a variety of indirect means, however,which suffer from model dependence and other problems. We describe adirect measurement of the SN rate from a regular patrol of starburstgalaxies done with K'-band imaging to minimize the effects ofextinction. A collection of K'-band measurements of core-collapse SNenear maximum light is presented. Such measurements (excluding 1987A) arenot well reported in the literature. Results of a preliminary K'-bandsearch, using the MIRC camera at the Wyoming Infrared Observatory and animproved search strategy using the new ORCA optics, are described. Amonthly patrol of a sample of IRAS bright (mostly starburst) galaxieswithin 25 Mpc should yield 1-6 SNe yr^-1, corresponding to the range ofestimated SN rates. Our initial MIRC search with low resolution (2.2"pixels) failed to find extinguished SNe in the IRAS galaxies, limitingthe SN rate outside the nucleus (at greater than 15" radius) to lessthan 3.8 far-IR SN rate units (SNe per century per 10^10 L_solarmeasured at 60 and 100 mum, or FIRSRU) at 90% confidence. The MIRCcamera had insufficient resolution to search nuclear starburst regions,where starburst and SN activity is concentrated; therefore, we wereunable to rigorously test the hypothesis of high SN rates in heavilyobscured star-forming regions. We conclude that high-resolution nuclearSN searches in starburst galaxies with small fields are more productivethan low-resolution, large-field searches, even for our sample of large(often several arcminutes) galaxies. With our ORCA high-resolutionoptics, we could limit the total SN rate to less than 1.3 FIRSRU at 90%confidence in 3 years of observations, lower than most estimates.
| Dense gas in nearby galaxies . XII. A survey for CO J=3-2 emission
The J=3-2 sub-mm line of (12) CO has been observed with theHeinrich-Hertz-Telescope (HHT) toward a sample of 28 nearby galaxies,and toward Arp 220. All sources are detected. This isthe largest extragalactic sample of CO 3-2 spectra published so far. The3-2 line fluxes, I32, are compared to 1-0 and 2-1 fluxesmeasured with the IRAM 30-m telescope. Model calculations show that theI32/I10 ratio can be used as a measure of theaverage H2 density. For most sources observed,I32/I10 is in the range 0.2-0.7, which ispredicted if kinetic temperatures are < 50 K and/or H2densities <1000 cm(-3) . Our measurements of the J=1-0, 2-1, and 3-2lines toward M 82 do not support earlier claims of2-1/1-0 line ratios much larger than 1. As in other active galaxies (NGC253, Arp 220) the measured line intensity ratio is close to unity.Unlike single dish data from the lower excited CO lines, the CO 3-2profile toward Arp 220 shows two velocity components,possibly arising from the edges of its molecular disk. Based onobservations with the Heinrich-Hertz-Telescope (HHT). The HHT isoperated by the Submillimeter Telescope Observatory on behalf of StewardObservatory and the MPI für Radioastronomie.
| The Pico DOS Dias Survey Starburst Galaxies
We discuss the nature of the galaxies found in the Pico dos Dias Survey(PDS) for young stellar objects. The PDS galaxies were selected from theIRAS Point Source catalog. They have flux density of moderate or highquality at 12, 25, and 60 μm and spectral indices in the ranges -3.00<= alpha(25, 12) <= + 0.35 and -2.50 <= alpha(60, 25) <=+0.85. These criteria allowed the detection of 382 galaxies, which are amixture of starburst and Seyfert galaxies. Most of the PDS Seyfertgalaxies are included in the catalog of warm IRAS sources by de Grijp etal. The remaining galaxies constitute a homogeneous sample of luminous[log F (L_B/L_ȯ) = 9.9 +/- 0.4] starburst galaxies, 67% of whichwere not recognized as such before. The starburst nature of the PDSgalaxies is established by comparing their L_IR/L_B ratios and IRAScolors with a sample of emission-line galaxies from the literaturealready classified as starburst galaxies. The starburst galaxies show anexcess of FIR luminosity, and their IRAS colors are significantlydifferent from those of Seyfert galaxies-99% of the starburst galaxiesin our sample have a spectral index alpha(60, 25) < -1.9. As opposedto Seyfert galaxies, very few PDS starbursts are detected in X-rays. Inthe infrared, the starburst galaxies form a continuous sequence withnormal galaxies. But they generally can be distinguished from normalgalaxies by their spectral index alpha(60, 25) > -2.5. This colorcutoff also marks a change in the dominant morphologies of the galaxies:the normal IRAS galaxies are preferentially late-type spirals (Sb andlater), while the starbursts are more numerous among early-type spirals(earlier than Sbc). This preference of starbursts for early-type spiralsis not new, but a trait of the massive starburst nucleus galaxies(Coziol et al.). As in other starburst nucleus galaxy samples, the PDSstarbursts show no preference for barred galaxies. No difference isfound between the starbursts detected in the FIR and those detected onthe basis of UV excess. The PDS starburst galaxies represent the FIRluminous branch of the UV-bright starburst nucleus galaxies, with meanFIR luminosity log (L_IR/L_ȯ) = 10.3 +/- 0.5 and redshifts smallerthan 0.1. They form a complete sample limited in flux in the FIR at 2 x10^-10 ergs cm^-2 s^-1.
| 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 Southern Sky Redshift Survey
We report redshifts, magnitudes, and morphological classifications for5369 galaxies with m_B <= 15.5 and for 57 galaxies fainter than thislimit, in two regions covering a total of 1.70 sr in the southerncelestial hemisphere. The galaxy catalog is drawn primarily from thelist of nonstellar objects identified in the Hubble Space TelescopeGuide Star Catalog (GSC). The galaxies have positions accurate to ~1"and magnitudes with an rms scatter of ~0.3 mag. We compute magnitudes(m_SSRS2) from the relation between instrumental GSC magnitudes and thephotometry by Lauberts & Valentijn. From a comparison with CCDphotometry, we find that our system is homogeneous across the sky andcorresponds to magnitudes measured at the isophotal level ~26 magarcsec^-2. The precision of the radial velocities is ~40 km s^-1, andthe redshift survey is more than 99% complete to the m_SSRS2 = 15.5 maglimit. This sample is in the direction opposite that of the CfA2; incombination the two surveys provide an important database for studies ofthe properties of galaxies and their large-scale distribution in thenearby universe. Based on observations obtained at Cerro TololoInter-American Observatory, National Optical Astronomy Observatories,operated by the Association of Universities for Research in Astronomy,Inc., under cooperative agreement with the National Science Foundation;Complejo Astronomico El Leoncito, operated under agreement between theConsejo Nacional de Investigaciones Científicas de laRepública Argentina and the National Universities of La Plata,Córdoba, and San Juan; the European Southern Observatory, LaSilla, Chile, partially under the bilateral ESO-ObservatórioNacional agreement; Fred Lawrence Whipple Observatory;Laboratório Nacional de Astrofísica, Brazil; and the SouthAfrican Astronomical Observatory.
| 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.
| The Average Properties of the Dense Molecular Gas in Galaxies
We have observed the HCN J = 3 --> 2 and J = 1 --> 0 emission fromseveral nearby starburst and normal galaxies. These lines have largecritical densities ( n_{{H}2} > 106 cm-3) and excitationenergies (Eu > 25 K). Thus, they probe the warm and dense moleculargas where massive stars typically form. The average cloud densities ofthese galaxies, as estimated from the ratio of the HCN J = 3 --> 2and 1 --> 0 integrated intensities, is correlated with their starformation efficiency. Therefore, the average densities of the molecularclouds in starburst nuclei are higher than those of more quiescentgalaxies. Further, the starburst galaxies NGC 253 and M82 have a muchhigher fraction of molecular mass at high density ( n_{{H}2}> 104 cm-3) than the normal galaxies IC 342 and the Milky Way. Theseresults imply that the clouds in starburst nuclei form stars moreefficiently than those in normal galaxies.
| Massive Star Formation Along the Hubble Sequence
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1997AJ....113..599D&db_key=AST
| 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.
| 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.
| A comparative study of morphological classifications of APM galaxies
We investigate the consistency of visual morphological classificationsof galaxies by comparing classifications for 831 galaxies from sixindependent observers. The galaxies were classified on laser print copyimages or on computer screen using scans made with the Automated PlateMeasuring (APM) machine. Classifications are compared using the RevisedHubble numerical type index T. We find that individual observers agreewith one another with rms combined dispersions of between 1.3 and 2.3type units, typically about 1.8 units. The dispersions tend to decreaseslightly with increasing angular diameter and, in some cases, withincreasing axial ratio (b/a). The agreement between independentobservers is reasonably good but the scatter is non-negligible. In spiteof the scatter, the Revised Hubble T system can be used to train anautomated galaxy classifier, e.g. an artificial neural network, tohandle the large number of galaxy images that are being compiled in theAPM and other surveys.
| The FCRAO Extragalactic CO Survey. I. The Data
Emission from the CO molecule at λ = 2.6 mm has been observed at1412 positions in 300 galaxies using the 14 m telescope of the FiveCollege Radio Astronomy Observatory (HPBW = 45"); these data comprisethe FCRAO Extragalactic CO Survey. In this paper we describe the galaxysample, present the data, and determine global CO fluxes and radialdistributions for the galaxies in the Survey. Future papers will dealwith the data analysis, both with regard to the global properties ofgalaxies and the radial distributions within them. CO emission wasdetected in 236 of the 300 Survey galaxies for an overall detection rateof 79%; among the 52 Sc galaxies in the Survey, the detection rate wasas high as 96%. most of the 193 galaxies observed in multiple positionsexhibit CO distributions which peak at the center. However, a smallnumber (10-primarily Sb galaxies) exhibit CO rings at 45" resolution,and a similar number (18-primarily Sc galaxies) have CO distributionswhich peak on one side of the center. We derive CO isophotal diametersfor 151 galaxies and find the mean ratio of CO to optical isophotaldiameters to be 0.5. We also find a trend along the Hubble sequence suchthat the mean ratio of CO to optical isophotal diameters is smallestamong the early-type spirals (SO/a, Sa, and Sab) and the mean ratioincreases for Sb, Sbc, and Sc galaxies, finally decreasing among thelater types. Comparison of the global fluxes we derive for the Surveygalaxies with independent measurements from the literature indicatesthat the global fluxes we derive are accurate to ~40%.
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