Tartalom
Képek
Kép feltöltése
DSS Images Other Images
Kapcsolódó cikkek
The Great Observatories All-sky LIRG Survey: Comparison of Ultraviolet and Far-infrared Properties
The Great Observatories All-sky LIRG Survey (GOALS) consists of acomplete sample of 202 luminous infrared galaxies (LIRGs) selected fromthe IRAS Revised Bright Galaxy Sample (RBGS). The galaxies span the fullrange of interaction stages, from isolated galaxies to interacting pairsto late stage mergers. We present a comparison of the UV and infraredproperties of 135 galaxies in GOALS observed by GALEX and Spitzer. Forinteracting galaxies with separations greater than the resolution ofGALEX and Spitzer (~2''-6''), we assess the UV and IR properties of eachgalaxy individually. The contribution of the FUV to the measured starformation rate (SFR) ranges from 0.2% to 17.9%, with a median of 2.8%and a mean of 4.0% ± 0.4%. The specific star formation rate(SSFR) of the GOALS sample is extremely high, with a median value (3.9× 10-10 yr-1) that is comparableto the highest SSFRs seen in the Spitzer Infrared Nearby Galaxies Surveysample. We examine the position of each galaxy on the IR excess-UV slope(IRX-?) diagram as a function of galaxy properties, including IRluminosity and interaction stage. The LIRGs on average have greater IRexcesses than would be expected based on their UV colors if they obeyedthe same relations as starbursts with L IR <1011 L sun or normal late-type galaxies. The ratioof L IR to the value one would estimate from the IRX-?relation published for lower luminosity starburst galaxies ranges from0.2 to 68, with a median value of 2.7. A minimum of 19% of the total IRluminosity in the RBGS is produced in LIRGs and ultraluminous infraredgalaxies with red UV colors (?>0). Among resolved interactingsystems, 32% contain one galaxy which dominates the IR emission whilethe companion dominates the UV emission. Only 21% of the resolvedsystems contain a single galaxy which dominates both wavelengths.
| The Role of Starburst-Active Galactic Nucleus Composites in Luminous Infrared Galaxy Mergers: Insights from the New Optical Classification Scheme
We investigate the fraction of starbursts, starburst-active galacticnucleus (AGN) composites, Seyferts, and low-ionization narrowemission-line region galaxies (LINERs) as a function of infraredluminosity (L IR) and merger progress for ~500 infrared(IR)-selected galaxies. Using the new optical classifications affordedby the extremely large data set of the Sloan Digital Sky Survey, we findthat the fraction of LINERs in IR-selected samples is rare (<5%)compared with other spectral types. The lack of strong IR emission inLINERs is consistent with recent optical studies suggesting that LINERscontain AGN with lower accretion rates than in Seyfert galaxies. Mostpreviously classified IR-luminous LINERs are classified as starburst-AGNcomposite galaxies in the new scheme. Starburst-AGN composites appear to"bridge" the spectral evolution from starburst to AGN in ULIRGs. Therelative strength of the AGN versus starburst activity shows asignificant increase at high IR luminosity. In ULIRGs (L IR> 1012 L sun), starburst-AGN composite galaxiesdominate at early-intermediate stages of the merger, and AGN galaxiesdominate during the final merger stages. Our results are consistent withmodels for IR-luminous galaxies where mergers of gas-rich spirals fuelboth starburst and AGN, and where the AGN becomes increasingly dominantduring the final merger stages of the most luminous IR objects.
| A Backward Evolution Model for Infrared Surveys: The Role of AGN– and Color–L TIR Distributions
Empirical "backward" galaxy evolution models for infrared (IR) brightgalaxies are constrained using multiband IR surveys. We developed a newMonte Carlo algorithm for this task, implementing luminosity-dependentdistribution functions for the galaxies' IR spectral energydistributions (SEDs) and for the active galactic nucleus (AGN)contribution, allowing for evolution of these quantities. The adoptedSEDs take into account the contributions of both starbursts and AGN tothe IR emission, for the first time in a coherent treatment rather thaninvoking separate AGN and star-forming populations. In the first part ofthe paper we consider the quantification of the AGN contribution forlocal universe galaxies, as a function of the total IR luminosity. It ismade using a large sample of luminous infrared galaxies andultraluminous infrared galaxies for which mid-IR spectra are availablein the Spitzer archive. We find the ratio of AGN 6 μm luminosity andthe total IR luminosity to rise with L 1.4 TIRover the IR luminosity range 1011-1013 Lsun and estimate its spread. Judging from the modest numberof distant sources with Spitzer spectroscopy, the relation changes athigh-z. In the second part we present the model. Our best-fit modeladopts very strong luminosity evolution, L = L 0(1 +z)3.4, up to z = 2.3, and density evolution, ρ =ρ0(1 + z)2, up to z = 1, for the population ofIR galaxies. At higher z, the evolution rates drop as (1 +z)–1 and (1 + z)–1.5, respectively. Toreproduce mid-IR to submillimeter number counts and redshiftdistributions, it is necessary to introduce both an evolution in the AGNcontribution and an evolution in the luminosity-temperature relation. Ata given total IR luminosity, high-redshift IR galaxies have typicallysmaller AGN contributions to the rest-frame mid-IR, and colder far-IRdust temperatures than locally. We also suggest an extension of thelocal IR galaxy population toward lower dust temperatures. Our modelsare in plausible agreement with current photometry-based estimates ofthe typical AGN contribution as a function of mid-IR flux, and wellplaced to be compared to upcoming Spitzer spectroscopic results. As anexample of future applications, we use our best-fitting model to makepredictions for surveys with Herschel.
| GOALS: The Great Observatories All-Sky LIRG Survey
The Great Observatories All-Sky LIRG Survey (GOALS) combines data fromNASA's Spitzer Space Telescope, Chandra X-Ray Observatory, Hubble SpaceTelescope (HST), and Galaxy Evolution Explorer (GALEX) observatories,together with ground-based data, into a comprehensive imaging andspectroscopic survey of over 200 low-redshift (F/F˜81) which iswell above the correlation seen in starburst galaxies. Most of thisexcess is driven by VV 340 N, which has an IR excess of nearly 400. TheVV 340 system seems to be comprised of two very different galaxies: aninfrared luminous edge-on galaxy (VV 340 north) that dominates thelong-wavelength emission from the system, which hosts a buried AGN; anda face-on starburst (VV 340 south) that dominates the short-wavelengthemission.
| The SCUBA Legacy Catalogues: Submillimeter-Continuum Objects Detected by SCUBA
We present the SCUBA Legacy Catalogues, two comprehensive sets ofcontinuum maps (and catalogs) using data at 850 and 450 μm of thevarious astronomical objects obtained with the Submillimetre Common UserBolometer Array (SCUBA). The Fundamental Map Data Set contains data onlywhere superior atmospheric opacity calibration data were available. TheExtended Map Data Set contains data regardless of the quality of theopacity calibration. Each data set contains1.2deg×1.2deg maps at locations where dataexisted in the JCMT archive, imaged using the matrix inversion method.The Fundamental Data Set is composed of 1423 maps at 850 μm and 1357maps at 450 μm. The Extended Data Set is composed of 1547 maps at 850μm. Neither data set includes high sensitivity, single-chop SCUBAmaps of ``cosmological fields'' nor solar system objects. Each data setwas used to determine a respective object catalogue, consisting ofobjects identified within the respective 850 μm maps using anautomated identification algorithm. The Fundamental and Extended MapObject Catalogues contain 5061 and 6118 objects, respectively. Objectsare named based on their respective J2000.0 position of peak 850 μmintensity. The catalogues provide for each object the respective maximum850 μm intensity, estimates of total 850 μm flux and size, andtentative identifications from the SIMBAD Database. Where possible, thecatalogues also provide for each object its maximum 450 μm intensityand total 450 μm flux and flux ratios.
| Kinematics of the Local Universe. XIII. 21-cm line measurements of 452 galaxies with the Nançay radiotelescope, JHK Tully-Fisher relation, and preliminary maps of the peculiar velocity field
Aims.This paper presents 452 new 21-cm neutral hydrogen linemeasurements carried out with the FORT receiver of the meridian transitNançay radiotelescope (NRT) in the period April 2003-March 2005. Methods: This observational programme is part of a larger projectaiming at an exhaustive and magnitude-complete HI extragalacticcatalogue for Tully-Fisher applications (the so-called KLUN project, forKinematics of the Local Universe studies, to end in 2008). The wholeon-line HI archive of the NRT today contains reduced HI-profiles for4500 spiral galaxies of declination δ > -40°(http://klun.obs-nancay.fr). Results: As an example of thisapplication, we used the direct Tully-Fisher relation in three (JHK)bands in deriving distances to a large catalogue of 3126 spiral galaxiesdistributed through the whole sky and sampling the radial velocity rangewell between 0 and 8000 km s-1. Thanks to an iterative methodaccounting for selection bias and smoothing effects, we show a detailedand original map of the velocity field in the Local Universe as apreliminary output.Data Tables [see full text], [see full text], and [see full text]and HI-profiles (Fig. [see full text]) are only available inelectronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr(130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/465/71
| Dust and CO emission towards the centers of normal galaxies, starburst galaxies and active galactic nuclei. I. New data and updated catalogue
Aims.The amount of interstellar matter in a galaxy determines itsevolution, star formation rate and the activity phenomena in thenucleus. We therefore aimed at obtaining a data base of the12CO line and thermal dust emission within equal beamsizesfor galaxies in a variety of activity stages. Methods: .We haveconducted a search for the 12CO (1-0) and (2-1) transitionsand the continuum emission at 1300 μm towards the centers of 88galaxies using the IRAM 30 m telescope (MRT) and the Swedish ESOSubmillimeter Telescope (SEST). The galaxies are selected to be brightin the far infrared (S100~μ m 9 Jy) and opticallyfairly compact (D25≤ 180 arcsec). We have applied opticalspectroscopy and IRAS colours to group the galaxies of the entire sampleaccording to their stage of activity into three sub-samples: normal,starburst and active galactic nuclei (AGN). The continuum emission hasbeen corrected for line contamination and synchrotron contribution toretrieve the thermal dust emission. For the latter we have determinedthe radio spectral indices of the individual sources and extrapolatedthe synchrotron emission corresponding to our millimeter beams to 1300μm. Results: .We present new observational data for the12CO (1-0) and (2-1) transitions and the thermal dustemission at 1300 μm for 88 galaxies. In conjunction with our previousdata, the new observations are used to compile an updated catalogue fora total of 160 galaxies.Based on observations collected at ESO, La Silla, Chile, and IRAM, PicoVeleta, Spain. Appendices A and B are only available in electronic format http://www.aanda.org
| Mid-Infrared Diagnostics of LINERS
We report results from the first mid-infrared spectroscopic study of acomprehensive sample of 33 LINERs, observed with the Spitzer SpaceTelescope. We compare the properties of two different LINER populations:infrared-faint LINERs, with LINER emission arising mostly in compactnuclear regions, and infrared-luminous LINERs, which often showspatially extended (non-AGN) LINER emission. We show that these twopopulations can be easily distinguished by their mid-infrared spectra inthree different ways: (1) their mid-IR spectral energy distributions(SEDs), (2) the emission features of polycyclic aromatic hydrocarbons(PAHs), and (3) various combinations of IR fine-structure line ratios.IR-luminous LINERs show mid-IR SEDs typical of starburst galaxies, whilethe mid-IR SEDs of IR-faint LINERs are much bluer. PAH flux ratios aresignificantly different in the two groups. Fine-structure emission linesfrom highly excited gas, such as [O IV], are detected in bothpopulations, suggesting the presence of an additional AGN in a largefraction of IR-bright LINERs as well, which contributes little to thecombined mid-IR light. The two LINER groups occupy different regions ofmid-infrared emission-line excitation diagrams. The positions of thevarious LINER types in our diagnostic diagrams provide important cluesregarding the power source of each LINER type. Most of thesemid-infrared diagnostics can be applied at low spectral resolution,making AGN- and starburst-excited LINERs distinguishable at highredshifts as well.
| Probing Cool and Warm Infrared Galaxies Using Photometric and Structural Measures
We have analyzed a sample of nearby cool and warm infrared (IR) galaxiesusing photometric and structural parameters. The set of measures includefar-infrared color [C=log(S60μm/S100μm)],total IR luminosity (LTIR), radio surface brightness, andradio, near-infrared, and optical sizes. In a given luminosity rangecool and warm galaxies are considered as those sources that are foundapproximately 1 σ below and above the mean color in thefar-infrared C-LTIR diagram. We find that galaxy radiosurface brightness is well correlated with color whereas size is lesswell correlated with color. Our analysis indicates that IR galaxies thatare dominated by cool dust are large, massive spirals that are notstrongly interacting or merging and presumably the ones with the leastactive star formation. Dust in these cool objects is less centrallyconcentrated than in the more typical luminous and ultraluminous IRgalaxies that are dominated by warm dust. Our study also shows thatlow-luminosity early-type unbarred and transitional spirals areresponsible for the large scatter in the C-LTIR diagram.Among highly luminous galaxies, late-type unbarred spirals arepredominately warm, and early-type unbarred and barred spirals aresystematically cooler. We highlight the significance of theC-LTIR diagram in terms of local and high-redshiftsubmillimeter galaxies.
| A catalogue of quasars and active nuclei: 12th edition
Aims.This catalogue is aimed at presenting a compilation of all knownAGN in a compact and convenient form and we hope that it will be usefulto all workers in this field.Methods.Like the eleventh edition, itincludes position and redshift as well as photometry (U, B, V) and 6 cmflux densities when available. We now give 20 cm rather than 11 cm fluxdensities.Results.The present version contains 85 221 quasars,1122 BL Lac objects and 21 737 active galaxies (including 9628 Seyfert1s), almost doubling the number listed in the 11th edition. We also givea list of all known lensed and double quasars.
| An Integrated Spectrophotometric Survey of Nearby Star-forming Galaxies
We present integrated optical spectrophotometry for a sample of 417nearby galaxies. Our observations consist of spatially integrated,S/N=10-100 spectroscopy between 3600 and 6900 Å at ~8 Å FWHMresolution. In addition, we present nuclear (2.5"×2.5")spectroscopy for 153 of these objects. Our sample targets a diverserange of galaxy types, including starbursts, peculiar galaxies,interacting/merging systems, dusty, infrared-luminous galaxies, and asignificant number of normal galaxies. We use population synthesis tomodel and subtract the stellar continuum underlying the nebular emissionlines. This technique results in emission-line measurements reliablycorrected for stellar absorption. Here we present the integrated andnuclear spectra, the nebular emission-line fluxes and equivalent widths,and a comprehensive compilation of ancillary data available in theliterature for our sample. In a series of subsequent papers we use thesedata to study optical star formation rate indicators, nebular abundancediagnostics, the luminosity-metallicity relation, the dust properties ofnormal and starburst galaxies, and the star formation histories ofinfrared-luminous galaxies.
| Dust-penetrated arm classes: insights from rising and falling rotation curves
In the last decade, near-infrared imaging has highlighted the decouplingof gaseous and old stellar discs: the morphologies of optical(Population I) tracers compared to the old stellar disc morphology, canbe radically different. Galaxies which appear multi-armed and evenflocculent in the optical may show significant grand-design spirals inthe near-infrared. Furthermore, the optically determined Hubbleclassification scheme does not provide a sound way of classifyingdust-penetrated stellar discs: spiral arm pitch angles (when measured inthe near-infrared) do not correlate with Hubble type. Thedust-penetrated classification scheme of Block & Puerari provides analternative classification based on near-infrared morphology, which isthus more closely linked to the dominant stellar mass component. Here wepresent near-infrared K-band images of 14 galaxies, on which we haveperformed a Fourier analysis of the spiral structure in order todetermine their near-infrared pitch angles and dust-penetrated armclasses. We have also used the rotation curve data of Mathewson et al.to calculate the rates of shear in the stellar discs of these galaxies.We find a correlation between near-infrared pitch angle and rate ofshear: galaxies with wide open arms (the γ class) are found tohave rising rotation curves, while those with falling rotation curvesbelong to the tightly wound α bin. The major determinant ofnear-infrared spiral arm pitch angle is the distribution of matterwithin the galaxy concerned. The correlation reported in this studyprovides the physical basis underpinning spiral arm classes in thedust-penetrated regime and underscores earlier spectroscopic findings byBurstein and Rubin that Hubble type and mass distributions areunrelated.
| 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.
| Near-infrared constraints on the driving mechanisms for spiral structure
We have imaged a sample of 17 inclined spiral galaxies with measuredHα rotation curves in the K band, in order to determine themorphology of the old stellar population that dominates the mass in thedisc. The K-band images of the galaxies have been used to determine theradial extent of grand-design spiral structure and compare this with theturnover radius in their rotation curves, where the rotation curvetransforms from solid-body rotation to differential rotation. If thearms do not extend past this radius, the winding problem is solved. Wefind in all 17 cases that the arms extend past this radius, with theradius of grand-design spiral structure being a factor of 1.3-9.6 timeslarger than the rotation curve turnover radius. Of these galaxies, fourhave near neighbours and central bars and a further seven have a centralbar. These bars or near neighbours may be the cause of the driving ofthe spiral potential in the discs of these galaxies. Of the remainingsix galaxies, five show some evidence for a bar or oval distortion intheir K-band images. The remaining galaxy (UGC 14) shows no evidence fora central bar and has no near neighbours.Finally, we also find that the spiral structure of these galaxies in thenear-infrared is extremely regular, although some range in theregularity of spiral structure is found. To quantify this range inspiral structure, we introduce the dust-penetrated arm class, which isanalogous to the dust-penetrated classification scheme of Block &Puerari and is based on the optical arm class of Elmegreen &Elmegreen.
| Optical Classification of Southern Warm Infrared Galaxies
In this paper, we present high-resolution optical spectra and opticalclassifications from our large sample of 285 warm infrared galaxies108
| Starburst or Seyfert? Adding a Radio and Far-Infrared Perspective to the Investigation of Activity in Composite Galaxies
It was once common to regard Seyfert and starburst galaxies ascompletely different types of object, but there is growing recognitionthat these classifications refer to the extremes of a continuousspectrum of galaxy types. In a previous study we investigated a sampleof galaxies with ambiguous optical emission-line ratios and concludedfrom near-infrared spectroscopic observations that the sample consistedof composite galaxies, containing both a starburst and an activegalactic nucleus (AGN). We now extend our study using radio synthesisand long-baseline interferometer observations made with the AustraliaTelescope, together with far-infrared IRAS observations, to discuss therelative contribution of starburst and AGN components to the overallluminosity of the composite galaxies. We find that only a small fractionof the radio emission (<10%) can be attributed to an AGN and that themajority of the far-infrared emission (>90%) is probably due to thestarburst component. We also show that an AGN contribution to theoptical emission of as little as 10% is sufficient to account for theambiguous line-ratio diagnostics.
| Starburst or Seyfert? Using Near-Infrared Spectroscopy to Measure the Activity in Composite Galaxies
We present near-infrared spectra for a sample of galaxies with ambiguousoptical emission-line ratios. These galaxies fall between starbursts andSeyferts in the usual optical diagnostic diagrams. We find a similarresult with the near-infrared emission-line ratios, which suggests thatthe galaxies are composite, containing both a starburst and an AGNcomponent. Furthermore, CO absorption, produced in late-type stars, isdetected within the sample, although at a weaker level than is typicalfor starburst galaxies. We conclude that the CO feature is being dilutedby a contribution from an AGN, thereby confirming the composite natureof these galaxies.
| 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.
| 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.
| 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 comprehensive search for extragalactic 6.7-GHz methanol masers
We have used the Australia Telescope Compact Array (ATCA) to search for6.7-GHz methanol maser emission towards 87 galaxies. We chose the targetsources using several criteria, including far-IR luminosities and thepresence of known OH megamasers. In addition, we searched for methanolmasers in the nearby starburst galaxy NGC 253, making a fullspectral-line synthesis image. No emission was detected in any of thegalaxies, with detection limits ranging from 25 to 75 mJy. This issurprising, given the close association of OH and methanol masers inGalactic star formation regions, and significantly constrains models ofOH megamaser emission. This absence of maser emission may be a result oflow methanol abundances in molecular clouds in starburst galaxies.
| 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
| Optical Rotation Curves and Linewidths for Tully-Fisher Applications
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1997AJ....114.2402C&db_key=AST
| AGNs with composite spectra.
The use of the Baldwin et al. (1981PASP...93....5B) or Veilleux &Osterbrock (1987ApJS...63..295V) diagnostic diagrams allows theunambiguous classification of the nuclear emission line regions of mostgalaxies into one of three categories: nuclear HII regions orstarbursts, Seyfert 2 galaxies and Liners. However, a small fraction ofthem have a "transition" spectrum. We present spectral observations of15 "transition" objects at high-dispersion (66Å/mm) around theHα, [NII]λλ6548,6584 and/or Hβ,[OIII]λλ4959,5007 emission lines. We show that most ofthese spectra are composite, due to the simultaneous presence on theslit of a Seyfert nucleus and a HII region. Seyfert 2s and Liners seemto occupy relatively small and distinct volumes in the three-dimensionalspace λ5007/Hβ, λ6584/Hα,λ6300/Hα.
| Spectroscopy of Luminous Infrared Galaxies at 2 Microns. II. Data for Galaxies with 11.2 <= (L IR/L ) 11.9
Spectra across the infrared K band are presented for a flux-limitedsample of powerful, bright, "infrared" galaxies. The sample in thepresent paper, consisting of 43 systems (47 individual galaxies) withinfrared luminosities LIR in the range 11.2 <~ log (LIR/Lȯ)<~ 11.9, was chosen from the IRAS Bright Galaxy Catalogue. Thespectra have resolving powers of ~340--680. When combined with the 13spectra we have already published for the "ultraluminous" galaxies,those with log (LIR/Lȯ) >~ 12.0, this constitutes the largestdatabase of high-quality infrared spectra yet assembled for awell-defined sample of galaxies. The spectra are, in general, dominatedby emission lines, which are due to the Br gamma hydrogen recombinationline and to several quadrupole transitions of excited molecularhydrogen. Emission from He I also appears frequently. Deep absorptionbands from CO are present in virtually all the spectra, as are a varietyof weaker stellar absorption features. The data are analyzed in acompanion paper (Paper III).
| Spectroscopy of Luminous Infrared Galaxies at 2 Microns. III. Analysis for Galaxies with log (L IR/L ) 11.2
We have obtained spectra across the K window for the first large sampleof luminous galaxies selected from the IRAS survey. This paper containsthe principal analysis of the 43 systems in our sample with luminositiesof 11.2 <~ log (LIR/Lȯ) <~ 11.9. The spectra themselves werepresented in a companion paper by Goldader et al. (Paper II). The Brgamma luminosities are proportional to LIR, at levels similar to thoseof star-forming regions. This strongly suggests that star formationaccounts for the bulk of the energy production in these objects, ingeneral agreement with previous studies. Good agreement is found for thecontinuous star formation models of Leitherer & Heckman with uppermass cutoffs well below 100 Msolar . The models accommodate arange in starburst ages of ~107 to 109 yr. Instantaneous starburstmodels fit the data but imply an unrealistically short range of ages forthe entire sample. It is difficult to avoid concluding that the initialmass functions are deficient in stars of less than ~1 Msolar. Strong emission lines from molecular hydrogen are detected. The H2 v =1--0 S(1) line luminosities are proportional to LIR; the correlationextends through the ultraluminous infrared galaxies. The H2 emission inthe galaxies tends to be more spatially extended than the Br gammaemission. Measured values and upper limits for the ratios of the variousH2 lines visible in our spectra indicate that the H2 seen in emission at2 mu m is consistent with being shock excited. However, othermechanisms, operating at sufficiently high densities that the H2 energylevels are thermalized by collisions, cannot be excluded. Based onenergy considerations, we suggest that the shocks are due to supernovaremnants expanding into the interstellar medium. The frequency of TypeII supernovae necessary to account for the H2 line emission agrees withfrequencies deduced from the starburst models and the radio/far-infraredcorrelation. However, there remain a number of galaxies that cannot bemade to fit this model. A decade after its discovery, a universalexplanation of the strong H2 emission in luminous infrared galaxiescontinues to elude us. No previously unrecognized broad-line activenuclei were discovered in our survey; either they are weak or absent orthe true optical depths at 2 mu m are much higher than indicated byconventional extinction measures. However, there are clear differencesbetween the K-band properties of galaxies that contain broad-line activenuclei and those that do not. The differences seem to be due to thepresence of strong nonstellar continuum emission coming from the activenuclei themselves. With the addition of the 13 ultraluminous galaxieswith log (LIR/Lȯ) >~ 12 from Goldader et al. (Paper I), thenumber of systems observed in this program totals 56. We haveincorporated these ultraluminous galaxies in some parts of the analysisto examine properties across the entire luminosity range of our sample.
| Parameters of 2447 Southern Spiral Galaxies for Use in the Tully-Fisher Relation
I-band luminosities, rotational velocities, and redshifts of 1092 spiralgalaxies have been measured by CCD photometry and Hα spectroscopyusing the 1 m and 2.3 m telescopes at Siding Spring Observatory,respectively. The results are tabulated. Luminosity profiles andHα rotation curves are given for the galaxies. When these resultsare combined with similar data for 1355 spiral galaxies publishedpreviously (Mathewson, Ford, & Buchhorn, hereafter Paper I), itprovides a large, uniform, and unique data set with which to measure,via the Tully-Fisher relation, the peculiar velocities of galaxies inthe local universe to a distance of 11,000 km s^-1^ (Mathewson &Ford). Taking advantage of the opportunity for publishing this data inmachine-readable form, in the CD-ROM, we have also included similar datafor the 1355 galaxies in Paper I.
| The bar-enhanced star-formation activities in spiral galaxies.
We use the ratio L_FIR_/L_B_ and the IRAS color index S_25_/S_12_ (bothwidely used as indices of relative star formation rates in galaxies) toanalyse subsets (containing no known AGNs or merging/interactinggalaxies) of: (a) the IRAS Bright Galaxy Sample, (b) galaxies from theoptically complete RSA sample which have IRAS detections in all fourbands, and (c) a volume-limited IR-unselected sample. We confirm thatIR-bright barred (SB) galaxies do, on average, have very significantlyhigher values of the FIR-optical and S_25_/S_12_ ratios (and presumably,higher relative star formation rates, SFR) than that do unbarred ones;the effect is most obvious in the IR colors. We also confirm that thesedifferences are confined to early-type (S0/a-Sbc) spirals and are notevident among late-type systems (Sc-Sdm). Unlike others, we see noenhancement of the SFR in weakly-barred (SAB) galaxies. We furtherconfirm that the effect of bars on the SFR is associated with therelative IR luminosity and show that it is detectable only in galaxieswith L_FIR_/L_B_>1/3, suggesting that as soon as they have anyeffect, bars translate their host galaxies into this relativelyIR-luminous group. Conversely, for galaxies with L_FIR_/L_B_ below ~0.1this luminosity ratio is lower among barred than unbarred systems, againconfirming and quantifying an earlier result. Although there is nosimple physical relation between H I content and star formation, astrong correlation of H I content with the presence of bars has beenfound for early-type spirals with L_FIR_/L_B_>1/3. This suggests thatthe availability of fuel is the factor determining just which galaxiesundergo bar-induced starbursts.
| 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".
| An image database. II. Catalogue between δ=-30deg and δ=70deg.
A preliminary list of 68.040 galaxies was built from extraction of35.841 digitized images of the Palomar Sky Survey (Paper I). For eachgalaxy, the basic parameters are obtained: coordinates, diameter, axisratio, total magnitude, position angle. On this preliminary list, weapply severe selection rules to get a catalog of 28.000 galaxies, wellidentified and well documented. For each parameter, a comparison is madewith standard measurements. The accuracy of the raw photometricparameters is quite good despite of the simplicity of the method.Without any local correction, the standard error on the total magnitudeis about 0.5 magnitude up to a total magnitude of B_T_=17. Significantsecondary effects are detected concerning the magnitudes: distance toplate center effect and air-mass effect.
|
Új cikk hozzáadása
Kapcsolódó hivatkozások
- - (nincs kapcsolódó hivatkozás) -
Új link hozzáadása
Besorolás csoportokba:
|
Pozíciós és asztrometriai adatok
Katalógusok és elnevezések:
|
