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Radio properties of FIR-megamaser nuclei
Aims.Radio data on the nuclear emissions have been used to characterizethe dominant nuclear activity in a sample of FIR (ultra-) luminousgalaxies and the subgroup of known OH Megamasers. This study complementsan earlier study of the optical classification of these Megamasernuclei.Methods.Classification of the radio activity in the nuclei isbased on three critical parameters: the radio brightness temperature,the radio spectral index, and the ratio of FIR and radio fluxes. A firstmethod gives equal weight to the three parameters and a second methoduses a weighted function to classify the nuclei.Results.The presentsample shows that only 43% of the sample shows some - weak or strong -AGN characteristics. About 66% of the OH-MM sample and 81% of thenon-OH-MM sample can be actually classified as Starburst-dominatedsources. Radio diagnostic diagrams using these diagnostic parametersshow a continuous distribution ranging between AGN-dominated andSBN-dominated sources. The diagnostic diagrams also support the notionthat AGNs and starbursts coexist in the nuclei.Conclusions.A comparisonof the radio and optical classifications shows a consistency in theextreme cases of clear SBN and AGNs. A significant part of the sourceswith optical AGN-like activity have an SBN classification in the radio.The discrepant classifications are discussed in order to arrive at afinal classification of the dominant power source in the nucleus.
| The Second Byurakan Survey. General Catalogue
The Second Byurakan Survey (SBS) General Catalogue is presented. TheSBS, a continuation of the Markarian survey reaching fainter limitingmagnitudes, is the first survey which combines the search of galaxiesand QSOs. A total area of 991OS#square;degrees of the Northern sky wascovered with the use of three objective prisms in combination withSchott filters. The limited magnitude on the best plates reached B ~19.5.The General Catalogue consists of 3563 objects presented in two parts: aCatalogue of galaxies (1863 objects) and one of stellar objects (1700objects). The Catalogue of SBS AGN consists of 761 objects (155 SyG, 596QSOs, and 10 BLLac). Multi-wavelength data are presented for 1438 SBSobjects identified with X-ray, IRAS and FIRST sources.Spectrophotometric observations obtained over 26 years are available for3132 objects. Redshifts were measured for ~ 2100 extragalactic objects.Spectral classification is presented for ~ 2970 objects. The majority ofthe data is presented here for the first time. The Catalogue presentsnew large homogeneous deep representative complete samples of brightQSOs, AGNs, and faint UVX galaxies in the Northern sky. The SBS sampleis found to be complete at 70% for galaxies and ~ 85% for AGN/QSOs withB ≤ 17.5.
| The Phenomenon of the Galaxy NGC 6286: A Forming Polar Ring or a Superwind?
We present our observations of the pair of interacting galaxies NGC6285/86 carried out with the 6-m Special Astrophysical Observatory (SAO)telescope using 1D and 2D spectroscopy. The observations of NGC 6286with a long-slit spectrograph (UAGS) near the H_alpha line revealed therotation of the gaseous disk around an axis offset by 5"-7" from thephotometric center and a luminous gas at a distance up to 9 kpc in adirection perpendicular to the galactic plane. Using a multipupil fiberspectrograph (MPFS), we constructed the velocity fields of the stellarand gaseous components in the central region of this galaxy, whichproved to be similar. The close radial velocities of the pair and thewide (5' x 5') field of view of the scanning Fabry-Perot interferometer(IFP) allowed us to simultaneously obtain images in the H_alpha and [NII] lambda 6583 lines and in the continuum, as well as to construct theradial velocity fields and to map the distribution of the [N II] lambda6583/H_alpha ratio for both galaxies. Based on all these data, westudied the gas kinematics in the galaxies, constructed their rotationcurves, and estimated their masses (2 x 10^{11} M_solar for NGC 6286 and1.2 x 10^{10} M_solar for NGC 6285). We found no evidence of gasrotation around the major axis of NGC 6286, which argues against theassumption that this galaxy has a forming polar ring. The IFPobservations revealed an emission nebula around this galaxy with astructure characteristic of superwind galaxies. The large [N II] lambda6583/H_aplha ratio, which suggests the collisional excitation of itsemission, and the high infrared luminosity are additional arguments forthe hypothesis of a superwind in the galaxy NGC 6286. A close encounterbetween the two galaxies was probably responsible for the starburst andthe bipolar outflow of hot gas from the central region of the disk.
| Radio Continuum Emission in Polar Ring Galaxies
We have used the Very Large Array aperture synthesis telescope toconduct a radio continuum survey of polar ring galaxies, at 20 cm and 6cm. Forty objects were observed at 20 cm with ~=5" resolution. Twenty(50%) of the program sources were detected at 20 cm, down to our 5σ limit of 0.5 mJy beam-1. This detection rate issimilar to those in surveys with comparable sensitivity for early-typegalaxies without polar rings. Sixteen of the objects we detected at 20cm were also observed at 6 cm. We show radio continuum maps for the fiveobjects in our sample that have noticeably extended emission. Ourspatial resolution was sufficient to distinguish emission originating inthe host galaxy from that in the polar ring. The radio morphology of theextended sources, as well as the ratio of radio to far-infrared flux andthe radio spectral indices of our detected sources, indicate that starformation, not nuclear activity, is the dominant source of the radiocontinuum emission in polar ring galaxies. However, the implied starformation rates are modest, and only one of our sample galaxies willconsume its supply of cool gas within 500 Myr.
| An IRAS High Resolution Image Restoration (HIRES) Atlas of All Interacting Galaxies in the IRAS Revised Bright Galaxy Sample
The importance of far-infrared observations for our understanding ofextreme activity in interacting and merging galaxies has beenillustrated by many studies. Even though two decades have passed sinceits launch, the most complete all-sky survey to date from which far-IRselected galaxy samples can be chosen is still that of the InfraredAstronomical Satellite (IRAS). However, the spatial resolution of theIRAS all-sky survey is insufficient to resolve the emission fromindividual galaxies in most interacting galaxy pairs, and hence previousstudies of their far-IR properties have had to concentrate either onglobal system properties or on the properties of very widely separatedand weakly interacting pairs. Using the HIRES image reconstructiontechnique, it is possible to achieve a spatial resolution ranging from30" to 1.5m (depending on wavelength and detector coverage), whichis a fourfold improvement over the normal resolution of IRAS. This issufficient to resolve the far-IR emission from the individual galaxiesin many interacting systems detected by IRAS, which is very importantfor meaningful comparisons with single, isolated galaxies. We presenthigh-resolution 12, 25, 60, and 100 μm images of 106 interactinggalaxy systems contained in the IRAS Revised Bright Galaxy Sample (RBGS,Sanders et al.), a complete sample of all galaxies having a 60 μmflux density greater than 5.24 Jy. These systems were selected to haveat least two distinguishable galaxies separated by less than threeaverage galactic diameters, and thus we have excluded very widelyseparated systems and very advanced mergers. Additionally, some systemshave been included that are more than three galactic diameters apart,yet have separations less than 4' and are thus likely to suffer fromconfusion in the RBGS. The new complete survey has the same propertiesas the prototype survey of Surace et al. We find no increased tendencyfor infrared-bright galaxies to be associated with other infrared-brightgalaxies among the widely separated pairs studied here. We find smallenhancements in far-IR activity in multiple galaxy systems relative toRBGS noninteracting galaxies with the same blue luminosity distribution.We also find no differences in infrared activity (as measured byinfrared color and luminosity) between late- and early-type spiralgalaxies.
| Optical Imaging of Very Luminous Infrared Galaxy Systems: Photometric Properties and Late Evolution
A sample of 19 low-redshift (0.03
| Seyfert galaxies in UZC-Compact Groups
We present results concerning the occurrence of Seyfert galaxies in anew automatically selected sample of nearby Compact Groups of galaxies(UZC-CGs). Seventeen Seyferts are found, constituting 3% of theUZC-CG galaxy population. CGs hosting and non-hosting a Seyfert memberexhibit no significant differences, except that a relevant number of Sy2is found in unusual CGs, all presenting large velocity dispersion(σ>400 km s-1), many neighbours and a high number ofellipticals. We also find that the fraction of Seyferts in CGs is 3times as large as that among UZC-single-galaxies, and results from anexcess of Sy2s. CG-Seyferts are not more likely than other CG galaxiesto present major interaction patterns, nor to display a bar. Our resultsindirectly support the minor-merging fueling mechanism.
| Photometric structure of polar-ring galaxies
The results of B, V, R surface photometry of three polar-ring galaxies(PRGs) - A 0017+2212, UGC 1198, UGC 4385 - are presented. The data wereacquired at the 6-m telescope of the Special Astrophysical Observatoryof the Russian Academy of Sciences. It was shown that all three galaxiesare peculiar late-type spirals in the state of ongoing interaction ormerging. We discuss available photometric properties of the PRGs withspiral hosts and consider the Tully-Fisher relation for different typesof PRGs. In agreement with Iodice et al. (\cite{Iodice03}), we haveshown that true PRGs demonstrate 1/3 larger maximum rotationvelocities than spiral galaxies of the same luminosity. Peculiar objectswith forming polar structures satisfy, on average, the Tully-Fisherrelation for disk galaxies but with large scatter.
| Physical Coupling of Kazarian Galaxies with Surrounding Galaxies
Results from a statistical study of Kazarian galaxies and the objectssurrounding them are presented. It is shown that: (1) the sample ofKazarian galaxies up to 16m.0 is complete. (2) Roughly 35.7% of theKazarian galaxies are members of clusters, 14.0% of groups, and 13.6% ofbinary systems, while 36.7% are single galaxies. (3) Of the 580 Kazariangalaxies, roughly 61.2% are infrared, 8.8% radio, and 2.8% x-raysources. (4) The relative numbers of Kazarian galaxies for completesamples of I, R, and X in the different groups are systematically higherthan the corresponding numbers for samples of all Kazarian galaxies.
| Near-Infrared photometry in J, H and Kn bands for polar ring galaxies. II. Global properties
We discuss the properties of the host galaxy and ring lightdistributions in the optical and near infrared bands for a sample ofPolar Ring Galaxies (PRGs), presented in Paper I (Iodice et al.\cite{paperI}). The goal of this work is to test different formationscenarios for PRGs, proposed by different authors in the last decades,by comparing their predictions with these new data. The strategy istwofold: i) the integrated colors of the main components in thesesystems are compared with those of standard morphological galaxy types,to investigate whether differences in colors are caused by dustabsorption or difference in stellar populations. We then derived anestimate of the stellar population ages in PRGs, which can be used toset constrains on the dynamical modeling and the time evolution of thesesystems; ii) we analyse the structural parameters of the host galaxy inorder to understand whether this component is a standard early-typesystem as its morphology suggests, and the light distribution in thepolar ring to measure its radial extension. These observational resultsindicate that the global properties of PRGs are better explained bydissipative merging of disks with un-equal masses as proposed by Bekki(1998), rather than the accretion-or stripping-of gas by a pre-existingearly-type galaxy.
| 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
| A search for extragalactic H2O maser emission towards IRAS galaxies. Detection of a maser from an infrared-luminous merger, NGC 6240
We report the result of an on-going survey for 22 GHz H2Omaser emission towards infrared luminous galaxies. The observed galaxieswere selected primarily from the IRAS bright galaxy sample. The surveyhas resulted in the detection of one new maser. The new maser wasdiscovered towards the [U]LIRG/merger galaxy NGC 6240, which contains aLINER nucleus. This is the first detection of an H2O; masertowards this class of galaxy, they are traditionally associated with OHmegamaser sources. The detected maser emission is highly redshifted ( ~260-300 km s-1;ss) with respect to the adopted systemicvelocity of the galaxy, and we identified no other significant emissionat velocities la +/-500 km s-1; relative to the systemicvelocity. The presence of high-velocity maser emission implies thepossible existence of a rotating maser disk formed in the mergingprocess. The large maser luminosity ( ~ 40 Lsun) suggeststhat an active galactic nucleus could be the energy source that givesrise to the water emission. Alternatively, the maser emission could beassociated with the previously observed double radio source in thecentre of the galaxy. Interferometric observations with high angularresolution will be able to clarify the origin of the new maser.
| The Structure of Infrared-luminous Galaxies at 100 Microns
We have observed 22 galaxies at 100 μm with the Kuiper AirborneObservatory in order to determine the angular size of their FIR-emittingregions. This one-dimensional array data constitutes the highest spatialresolution ever achieved on luminous galaxies in the far-infrared. Mostof these galaxies are very luminous far-infrared sources, withLFIR>1011 Lsolar. We clearlyresolved six of these galaxies at 100 μm and have some evidence forextension in seven others. Those galaxies that we have resolved can havelittle of their 100 μm flux directly emitted by a pointlike activegalactic nucleus. Dust heated to ~40 K by recent bursts of nonnuclearstar formation provides the best explanation for their extreme FIRluminosity. In a few cases, heating of an extended region by a compactcentral source is also a plausible option.
| Optical Spectral Signatures of Dusty Starburst Galaxies
We analyze the optical spectral properties of the complete sample ofVery Luminous Infrared Galaxies presented by Wu et al., and we find ahigh fraction (~50%) of spectra showing both a strong Hδ line inabsorption and relatively modest [O II] emission [e(a) spectra]. Thee(a) signature has been proposed as an efficient method to identifydusty starburst galaxies, and we study the star formation activity andthe nature of these galaxies, as well as the effects of dust on theirobserved properties. We examine their emission-line characteristics, inparticular their [O II]/Hα ratio, and we find this to be greatlyaffected by reddening. A search for AGN spectral signatures reveals thatthe e(a) galaxies are typically H II/LINER galaxies. We compare the starformation rates derived from the FIR luminosities with the estimatesbased on the Hα line and find that the values obtained from theoptical emission lines are a factor of 10-70 (Hα) and 20-140 ([OII]) lower than the FIR estimates (50-300 Msolaryr-1). We then study the morphological properties of the e(a)galaxies, looking for a near companion or signs of a merger/interaction.In order to explore the evolution of the e(a) population, we present anoverview of the available observations of e(a) galaxies in differentenvironments both at low and high redshift. Finally, we discuss the roleof dust in determining the e(a) spectral properties and we propose ascenario of selective obscuration in which the extinction decreases withthe stellar age.
| Accurate optical positions for 2978 objects from the Second Byurakan Survey (SBS) with the Digitized Sky Survey
Optical positions of 2978 objects listed in the Second Byurakan Survey(SBS) were obtained using the Digitized Sky Survey (DSS), and are givenwith an rms uncertainty ~ 1 arcsec in each coordinate. Tables 1 and 2are only available in electronic form at the CDS via anonymous ftp130.79.128.5 or via http://cdsweb.u-strasbg.fr/Abstract.html
| A neutral hydrogen survey of polar ring galaxies. III. Nançay observations and comparison with published data
A total of 50 optically selected polar ring galaxies, polar ring galaxycandidates and related objects were observed in the 21-cm H i line withthe Nançay decimetric radio telescope and 31 were detected. Theobjects, selected by their optical morphology, are all north ofdeclination -39o, and generally relatively nearby (V< 8000km s-1) and/or bright (mB< 15.5). The H i linedata are presented for all 74 galaxies observed for the survey with theEffelsberg, Green Bank or Nanç radio telescopes, as well as allother published H i line parameters of these objects. Three objects wereobserved and detected by us at Parkes. A total of 59 objects weredetected. For each object a brief description is given based on aliterature search.
| 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.
| Optical Classification of Megamaser Galaxies
We have obtained spectroscopic observations of the nuclear regions of 42galaxies known to harbor strong OH masers. These megamaser galaxiesrepresent a subsample of FIR (ultra)luminous galaxies, which typicallyhave FIR luminosities in excess of 10^11 L_ȯ. The primary goal ofthis study is to investigate the nuclear activity sources of OHmegamaser galaxies. We are able to classify the nuclear emission-linespectra of all but one of our sample, and we find that this class ofgalaxies is dominated by active galactic nuclei (AGNs), althoughstarburst galaxies do make up an appreciable fraction of the megamasersas well. Fully 45% of the megamasers exhibit Seyfert or LINER spectra,predominantly of Seyfert 2 type, although two galaxies with broad linesare observed. This observation is consistent with the currentunification models for the two types of Seyfert activity, since theassumed geometry necessary to detect a megamaser places the Seyfertnucleus behind a high column density of molecular gas (i.e., themolecular torus). Starburst-nucleus galaxies comprise 32.5% of oursample, while 22.5% are classified as ``composite nuclear spectra''(CSN) sources, showing evidence of both AGN and starburst activity. Anumber of objects show unusual emission-line ratios, not surprising fora group of galaxies that are known a priori to possess substantialabsorbing material along the line of sight to their nuclei. Our resultsare compared to previous studies of FIR-selected galaxy samples, as wellas to radio-continuum observations of these galaxies. The activityclassification obtained from the radio data disagrees with the opticalclassifications in roughly 25% of the sources; we discuss possibleexplanations for these discrepancies.
| Starburst Galaxies. III. Properties of a Radio-selected Sample
We have analyzed the properties of the 20 most radio-luminous UGCstarburst galaxies from Condon, Frayer, & Broderick. Near-infraredimages, spectra, and optical rotation curves were presented in Smith etal. In this paper, we use these data and published radio data to assessthe stellar populations, dust contents, ionizing conditions, anddynamics of the starbursts. Certain properties of the star formationoccurring in these galaxies differ from those observed locally. Theinfrared excesses (IREs) are lower than and span a narrower range ofvalues than those of Galactic H II regions. The starbursts appear toproduce a higher proportion of ionizing photons than most Galactic H IIregions. Consequently, the initial mass functions (IMFs) of thestarbursts may be more strongly biased toward high-mass star formation.The starbursts may also contain fewer old H II regions than the MilkyWay. Furthermore, the starburst IRE is likely to be influenced by thepresence of large reservoirs of gas that absorb a larger fraction of theLyman continuum photons. The OB stellar and far-infrared luminositiesimply that the upper mass range of the starburst IMF (M > 10 Mȯ)is characterized by a slope of 2.7 +/- 0.2. The starburst IMF thus bearsa strong similarity to that observed in Magellanic OB associations.Optical line ratios indicate that a range of excitation conditions arepresent. We conclude that the near-infrared light from many of thestarbursts is dominated by a heavily obscured mixture of emission fromevolved red stars and young blue stars with small contributions (~5%)from thermal gas and hot dust, under the assumptions that a Galactic orSMC extinction law can be applied to these systems and that the truereddening curve follows one of the models currently existing in theliterature. In some cases, larger amounts of emission from blue stars orhot dust may be required to explain the observed near-infrared colors.The amount of dust emission exceeds that predicted from comparisons withGalactic H II regions. The near-infrared colors of some of the systemsmay also be influenced by the presence of a low-luminosity activegalactic nucleus (AGN). Emission from blue stars and hot dust, ifpresent, dilutes the observed CO index. The activity in the redder, moreluminous systems is strongly peaked. The galaxies hosting the starburstsexhibit a wide range of morphological and star-forming properties. Whileall of the host galaxies are interacting systems, the nuclearseparations of the interacting nuclei range from <1 kpc to >1 Mpc.The dynamical behavior ranges from relaxed to strongly perturbed. Theoff-nuclear regions of the galaxies are sites of active star formationand are characterized by a range of excitation conditions. Spatiallyextended LINER emission is consistent with shock excitation produced bysuperwinds or galaxy-galaxy collisions. Violent star formation activityoccurs over a larger physical scale in the most active starbursts.Systems containing mergers and widely separated nuclei possess similarcolors and luminosities. The burst properties are most likely regulatedby the internal structures of the interacting galaxies and not theseparations of the interacting galaxies.
| A statistical study of the spectra of very luminous IRAS galaxies. II. Spectral and environmental analysis
Spectroscopic observations of a sample of 73 very luminous IRAS galaxies(log(LIR/Lsun)>=11.5 for H0=50 km\s(-1) ; Mpc(-1) ,q0=0.5) from the 2 Jy redshift surveycatalogue were carried out using the 2.16 m telescope at the BeijingAstronomical Observatory. The observational data, including the opticalimages (extracted from Digital Sky Survey) and spectra for thesegalaxies, are presented in Paper I \cite[(Wu et al. 1998)]{wu98}. Inthis paper, we give the spectral and morphological classifications forthese very luminous IRAS galaxies (VLIRGs). We show that about 60% ofVLIRGs exhibit AGN-like spectra (Seyfert 1s, Seyfert 2s, LINER-likegalaxies). This fraction goes up to 82% for the ultraluminous IRASgalaxies (ULIRGs) subsample (Log(LIR/Lsun) >=12.0). 56% of the VLIRGs show strong interaction or merging signatures;this fraction rises to 91% for the ULIRGs. These statistical resultsstrongly suggest that interaction triggers nuclear activities andenhances the infrared luminosity. We find that LINER and a mixture typewhich have optical properties of both HII galaxies and LINERs could beat the transition stage from infrared luminous HII galaxies to AGNs;their main energy production is from starbursts as well as AGNs. Bothinfrared luminosities and Hα equivalent widths increasedramatically as nuclear separations between VLIRGs and their nearestneighbors decrease. There is little doubt that strong starbursts happenin the nuclei of VLIRGs. Assuming class 0 as advanced merger, weconstruct a simple merger sequence, from morphological classes 1 to 4(with near or far companions), to class 5 and 6 (interacting pairs andmergers) and then to class 0 (isolated galaxies). Along this sequence,VLIRGs evolve from HII galaxies to AGNs. Table 1 is only available atthe CDS via anonymous ftp 130.79.128.5 or http://cdsweb.u-strasbg.fr
| A statistical study of the spectra of very luminous IRAS galaxies. I. Data
This paper presents the results of spectral observations for the largestcomplete sample of very luminous IRAS galaxies obtained to date. Thesample consists of those 73 objects for which log(L_IR/Lsun)>= 11.5 (H0=50;km; s(-1) Mpc(-1) , q0=0.5) andmag <= 15.5 , and was extracted from the 2 Jy IRAS redshift catalog.All the spectra were obtained using the 2.16 m telescope of BeijingAstronomical Observatory during the years 1994-1996. A total of 123galaxy spectra were obtained with spectral ranges of 4400;Angstroms to7100;Angstroms and 3500;Angstroms to 8100;Angstroms at resolutions of11.2;Angstroms and 9.3;Angstroms respectively. In addition to the 73spectra for sample galaxies, we also present spectra for ten non-samplegalaxies and a further 40 for the companions of sample galaxies. Thedata presented include nuclear spectrum and the parameters describingthe emission lines, absorption lines and continua as well as DSS imagesand environmental parameters. Table 1 is also available in electricform, Table 2-4 are only available in electronic form form at the CDSvia anonymous ftp to cdsarc.u-strasbg.fr (130. 79.128.5) or via http:cdsweb.u-strasbg.fr/Abstract.html. Figures 4 and 9 are published in theon-line version of A&A..
| 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
| Molecular gas in polar-ring galaxies
We present CO J=1-->0 observations (lambda=2.6 mm) of 10 polar-ringgalaxies, chosen from the Polar Ring Catalogue; we infer masses of H_2ranging from 7x10^7 to 2x10^10 Msolar, with an average of about 1x10^9Msolar. These H_2 masses are greater than the average molecular mass ofan early-type galaxy; we previously found similar results for a sampleof minor-axis dust-lane ellipticals. In the cases where we can estimatethe gas mass in the polar ring, including the H i masses fromliterature, they are high enough to allow self-gravitation to stabilizethe rings. This means that the ages of the rings may be >=1 Gyr.Indeed, the gas masses are often greater than those of most dwarfgalaxies: this would make it unlikely that the polar rings result fromthe recent accretion of a single gas-rich dwarf. A survey of the fieldsaround our sample galaxies shows in all but one case the presence of atleast one companion with either a similar redshift or similar bluemagnitude; these companions are close enough to have encountered thepolar-ring galaxy in <1 Gyr. The companion galaxies may be the sourceof the detected gas, through tidal stripping.
| 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.
| Spectral Observations of Faint Markarian Galaxies of the Second Byurakan Survey
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1997AJ....113.1527C&db_key=AST
| Global structure and formation of polar-ring galaxies.
We present an analysis of structural features of all known galaxies withoptical polar rings. We find a clear dichotomy for objects of thispeculiar class. Bulge-dominated S0 galaxies possess only short narrowrings, while disk-dominated objects always have wide extended polarrings. We try by gas dynamical simulations to explain such a segregationby dependence of the ring-forming process on different galaxypotentials. It is found that the total mass captured into the ringduring an encounter of a host-ring system with a gas-rich spiral galaxyof comparable mass exceeds 10^9^Msun_ (or about 10% of allgas in the donor galaxy), which is of the order of that found byobservation. The process of gas to gather into a steady-state ring takesapproximately (7-9)x10^8^years. This time is somewhat shorter for ringsforming around bulge-dominated galaxies. We also present observationalarguments for S0 galaxies with extended rings to be similar to late-typespirals by their photometric properties, while numerical modelling ofthe extended ring formation suggests that these galaxies must possessmassive dark halos as well. In this case, the sizes of the modelledrings turn out large enough (up to 30kpc in diameter), and the timescale for ring formation is prolonged up to several Gyrs.
| An HI survey of polar ring galaxies. II. The Effelsberg sample.
We present the results of a neutral hydrogen survey conducted with the100-m radiotelescope at Effelsberg of 44 northern objects in thepolar-ring galaxy atlas of Whitmore et al. (1990AJ....100.1489W). Theseobservations were performed to complement the Green Bank observations ofpolar-ring galaxies (Paper I, 1994AJ....107...99R). We detected 29 ofthese above our detection limit of a few mJy. The relative content ofneutral hydrogen (M_HI_/L_B_) of the early-type galaxies (E, S0) in thissample is significantly higher than for galaxies of the samemorphological types from comparison samples, i.e. for ellipticalgalaxies M_HI_/L_B_=0.17+/-0.09 and for S0 galaxiesM_HI_/L_B_=0.75+/-0.13 which is about 6 times the mean value from thecomparison samples for the same morphological types.
| Morphological classification of new galaxies with a UV excess
The results of a morphological classification of 580 galaxies with a UVexcess, included in the lists in [M. A. Kazarian, Astrofizika,15, 5(1979); ibid.,15, 193 (1979); M. A. Kazarian and É. S. Kazarian,ibid.,16, 17 (1980); ibid.,18, 512 (1982); ibid.,19, 213 (1983)], arepresented. For this we have developed a set of symbols, using the typesE, S, and Ir introduced by Hubble, as well as symbols introduced byother authors and us. This set enabled us to make the morphologicalclassification. Direct photographs obtained on the 2.6-m and 6-mtelescopes were used to classify 141 of the galaxies (over 24%), whilePalomar Atlas charts were used for the remaining 439 galaxies. Thesegalaxies were divided into two groups based on classificationconditions, and data on each group are given in Tables 1 and 2,respectively. The results for each group, given in Table 3, show thatwith the transition from early types, such as C and E, to later types,such as S and Ir, the relative number of galaxies going into one group(Table 1), in which the classification was based on direct photographs,increases in comparison with the number going into the other group(Table 2).
| Photometric study of polar-ring galaxies. III. Forming rings.
We present the results of detailed surface photometry of NGC 3808B andNGC 6286 - two spiral galaxies with possibly forming ring-likestructures rotating around major axes of the galaxies. The formation ofrings in NGC 3808B and NGC 6286 being accompanied by accretion of matteron galactic disk results in some interesting gasdynamical andstellar-dynamical effects in these galaxies. One can note, for instance,peculiar rotation curve of NGC 3808B gaseous disk; strong infrared andHα emission from the galaxies; bending and flaring stellar disksin both galaxies. Our observations clearly illustrate the possibilitythat polar-ring galaxies may be formed as a result of matter accretionfrom one galaxy to another.
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