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Spectrophotometry of galaxies in the Virgo cluster. II. The data
Drift-scan mode (3600-6800 Å) spectra with 500
| Radio emission from AGN detected by the VLA FIRST survey
Using the most recent (April 2003) version of the VLA FIRST survey radiocatalog, we have searched for radio emission from >2800 AGN takenfrom the most recent (2001) version of the Veron-Cetty and Veron AGNcatalog. These AGN lie in the 9033 square degrees of sky alreadycovered by the VLA FIRST survey. Our work has resulted in positivedetection of radio emission from 775 AGN of which 214 are new detectionsat radio wavelengths.Tables 3 and 4 are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/416/35
| 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
| Classifications of the Host Galaxies of Supernovae
Classifications on the DDO system are given for the host galaxies of 177supernovae (SNe) that have been discovered since 1997 during the courseof the Lick Observatory Supernova Search with the Katzman AutomaticImaging Telescope. Whereas SNe Ia occur in all galaxy types, it isfound, at a high level of statistical confidence, that SNe Ib, Ic, andII are strongly concentrated in late-type galaxies. However, attentionis drawn to a possible exception provided by SN 2001I. This SN IInoccurred in the E2 galaxy UGC 2836, which was not expected to harbor amassive young supernova progenitor.
| JHK' Imaging Photometry of Seyfert 1 Active Galactic Nuclei and Quasars. II. Observation of Long-Term Variability
Observations of 226 AGNs in the near-infrared J, H, and K' bands arepresented along with the analysis of the observations for variability.Our sample consists mainly of Seyfert 1 AGNs and QSOs. About a quarterof the objects in each category are radio loud. The AGNs in the entiresample have the redshifts spanning the range from z=0 to 1, and theabsolute magnitudes from MB=-29 to -18. All the objects wereobserved twice, and their variability was measured by differentialphotometry. A reduction method of differential photometry, optimized tothe analysis of extended images, has been developed. The systematicerror in variability arising from AGNs of highly extended images isestimated to be less than 0.01 mag in each of the J, H, and K' bands.The systematic error arising from the flat-fielding is negligible formost AGNs, although it is more than 0.1 mag for some particular cases.The overall average flat-fielding error is 0.03 mag for the image pairs.We find that these systematic errors are superseded by statisticalerrors, and the overall average total systematic and statistical errorsamounts to 0.05 mag in the measured variability in each band. We findthat 58% of all the AGNs in the entire sample show variability of morethan 2 σ, and 44% of more than 3 σ. This result holdsindependent of the J, H, and K' bands. The detection rate of variabilityis higher for a subsample of higher photometric accuracy, and thereappears no limit to this tendency. In particular, when we consider asubsample with small photometric errors of σ<0.03 mag, the rateof 2 σ detection is 80%, and 64% for 3 σ detection. Thissuggests that most AGNs are variable in the near-infrared.
| JHK' Imaging Photometry of Seyfert 1 Active Galactic Nuclei and Quasars. I. Multiaperture Photometry
Near-infrared JHK' imaging photometry was obtained of 331 AGNsconsisting mainly of Seyfert 1 active galactic nuclei (AGNs) and quasars(QSOs). This sample was selected to cover a range of radio emissionstrength, redshift from z=0 to 1, and absolute B magnitude fromMB=-29 mag to -18 mag. Among low-z AGNs with z<0.3,Seyfert 1-1.5 AGNs are distributed over a region from a location typicalof ``galaxies'' to a location typical of ``QSOs'' in the two-color J-Hto H-K' diagram, but Seyfert 1.8-2 AGNs are distributed around thelocation of ``galaxies.'' Moreover, bright AGNs with respect to absoluteB magnitude are distributed near the location of ``QSOs,'' while faintAGNs are near the location of ``galaxies.'' The distribution of suchlow-z AGNs in this diagram was found to have little dependence on their6 cm radio flux. The near-infrared colors of the AGNs observed with anaperture of 7 pixels (7.49") are more QSO-like than those observed withlarger apertures up to 15 pixels (16.1"). This aperture effect may beexplained by contamination from the light of host galaxies within largerapertures. This effect is more prominent for less luminous AGNs.
| Supernova 2001Z in IC 3528
IAUC 7592 available at Central Bureau for Astronomical Telegrams.
| Supernova 2001Z in IC 3528
IAUC 7593 available at Central Bureau for Astronomical Telegrams.
| Hubble Space Telescope observations of X-ray-selected active galactic nuclei
We report on the initial results of a comprehensive Hubble SpaceTelescope (HST) snapshot imaging survey of 76 low-redshift (z<0.15)X-ray-selected active galactic nuclei (AGN) in the Einstein ExtendedMedium Sensitivity Survey. This survey is expected to show no bias withrespect to host galaxy types, and so is arguably one of the bestavailable samples with HST imaging for the study of the host galaxies.The HST observations in the F814W band are complemented by deeperground-based observations in the B and R bands for most AGN. Theabsolute magnitudes for AGN in this sample lie in the range-24
| 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.
| 1.65 ^mum (H-band) surface photometry of galaxies. IV. observations of 170 galaxies with the Calar Alto 2.2 m telescope
We present near-infrared (H band) surface photometry of 170 galaxies,obtained in 1997 using the Calar Alto 2.2 m telescope equipped with theNICMOS3 camera MAGIC. The majority of our targets are selected amongbright members of the Virgo cluster, however galaxies in the A262 andCancer clusters and in the Coma/A1367 supercluster are also included.This data set is aimed at complementing the NIR survey in the Virgocluster discussed in \cite[Boselli et al. (1997)]{B97} and in the ComaSupercluster, presented in Papers I, II and III of this series.Magnitudes at the optical radius, total magnitudes, isophotal radii andlight concentration indices are derivedTables 1 and 2 (full version) are only available in electronic form atthe CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html.Based on observations taken at the Calar Alto Observatory, operated bythe Max-Planck-Institut für Astronomie (Heidelberg) jointly withthe Spanish National Commission for Astronomy.
| 1.65 μm (H-band) surface photometry of galaxies. V. Profile decomposition of 1157 galaxies
We present near-infrared H-band (1.65 μm) surface brightness profiledecomposition for 1157 galaxies in five nearby clusters of galaxies:Coma, A1367, Virgo, A262 and Cancer, and in the bridge between Coma andA1367 in the ``Great Wall". The optically selected (mpg≤16.0) sample is representative of all Hubble types, from E to Irr+BCD,except dE and of significantly different environments, spanning fromisolated regions to rich clusters of galaxies. We model the surfacebrightness profiles with a de Vaucouleurs r1/4 law (dV), withan exponential disk law (E), or with a combination of the two (B+D).From the fitted quantities we derive the H band effective surfacebrightness (μe) and radius (re) of each component, theasymptotic magnitude HT and the light concentration indexC31. We find that: i) Less than 50% of the Ellipticalgalaxies have pure dV profiles. The majority of E to Sb galaxies is bestrepresented by a B+D profile. All Scd to BCD galaxies have pureexponential profiles. ii) The type of decomposition is a strong functionof the total H band luminosity (mass), independent of the Hubbleclassification: the fraction of pure exponential decompositionsdecreases with increasing luminosity, that of B+D increases withluminosity. Pure dV profiles are absent in the low luminosity rangeLH<1010 L\odot and become dominantabove 1011 L\odot . Based on observations taken atTIRGO, Gornergrat, Switzerland (operated by CAISMI-CNR, Arcetri,Firenze, Italy) and at the Calar Alto Observatory (operated by theMax-Planck-Institut für Astronomie (Heidelberg) jointly with theSpanish National Commission for Astronomy). Table 2 and Figs. 2, 3, 4are available in their entirety only in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| On the local radio luminosity function of galaxies. I. The Virgo cluster
We cross-correlate the galaxies brighter than m_B=18 in the Virgocluster with the radio sources in the NVSS survey (1.4 GHz), resultingin 180 radio-optical identifications. We determine the radio luminosityfunction of the Virgo galaxies, separately for the early- andlate-types. Late-type galaxies develop radio sources with a probabilityproportional to their optical luminosity. In fact their radio/optical(R_B) distribution is gaussian, centered at log R_B ~ -0.5, i.e. theradio luminosity is ~ 0.3 of the optical one. The probability oflate-type galaxies to develop radio sources is almost independent oftheir detailed Hubble type, except for Sa (and S0+S0a) which are afactor of ~ 5 less frequent than later types at any R_B. Giantelliptical galaxies feed ``monster" radio sources with a probabilitystrongly increasing with mass. However the frequency of fainter radiosources is progressively less sensitive on the system mass. The faintestgiant E galaxies (M_B=-17) have a probability of feeding low power radiosources similar to that of dwarf E galaxies as faint as M_B=-13. Table~1is only available in electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| 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..
| FAUST Observations of Ultraviolet Sources toward the Virgo Cluster
We analyze three UV images covering a ~100 square degree field towardthe Virgo cluster, obtained by the FAUST space experiment. We detect 191sources to a signal-to-noise ratio of 4.4 and identify 94% of them. Mostsources have optical counterparts in existing catalogs, and about halfare identified as galaxies. Some sources with no listed counterpart wereobserved at the Wise Observatory. We present the results oflow-resolution visible spectrophotometry and discuss the foreground 101stellar sources and the 76 detected galaxies, both in the cluster and inthe foreground or background. We derive conclusions on star formationproperties of galaxies and on the total UV flux from discrete anddiffuse sources in the cluster. We test for the presence of intraclusterdust, determine the clustering properties of UV emitting galaxies, andderive the UV luminosity function of Virgo galaxies.
| Seyfert Galaxies With Companions: Orbital and Kinematic Clues to AGN Triggering
This paper presents imaging and optical spectroscopy of paired Seyfertgalaxies and their companions. The aim is to seek common properties ofSeyfert galaxies in interacting systems, which might provide evidence ofAGN triggering in a way independent of the usual two-sample statisticswhich have proven ambiguous on this issue. Three kinds of comparisonhave been made-the kinds of interactions involving Seyfert galaxies, therelative luminosities of the Seyferts and their companions, and thelevel of kinematic disturbance as measured from rotation curves. (1)Dynamics and tidal features have been used to determine (or at leastlimit) the sense of orbital motion (direct/retrograde/polar with respectto the Seyfert galaxy's disk) for many of these pairs. There is noobviously preferred kind of interaction-direct, polar, and retrogradeencounters are all well represented, despite the gross differences indynamical response of a disk to these various kinds of encounter. To theextent that triggering of Seyfert nuclei occurs due to tidal encounters,the existence of a perturbation seems more important than its exactduration or detailed effects on the disk. However, the ratio of mergingto paired Seyferts is higher than for disk galaxies in general,consistent with more effective triggering of AGN in this specific phase;the implied time scale for enhanced occurrence during mergers is thesame as the timescape for merger remnants to appear as such, a fewdisk-edge crossing times (typically several times 10^8^ yr). (2) Seyfertnuclei occur preferentially in the brighter members of galaxy pairs, bya median of 0.93 mag after making the maximal correction forcontaminating nonstellar light in the nuclei. Only about 1/3 of thiseffect can be accounted for by the known tendency of Seyfert nuclei tooccur in more luminous galaxies. Enhancement of AGN by interactions isevidently more effective for more luminous galaxies (though this willalso be the case if both star formation and AGN occurrence are enhancedin the same galaxies). (3) The rotation curves of the paired Seyfertsshow systematically small regions of rising or solid-body rotationcompared to the disk radius, as a group comparable to Sa but verydifferent from Sb or Sc galaxies (even for Seyfert galaxies with Hubbletype later than Sa). There is weak evidence that this difference is alsopresent with respect to more isolated Seyfert galaxies. Despite theobvious utility of a dynamically disturbed disk for transport of angularmomentum and "feeding the monster," Seyfert galaxies in pairs actuallyhave smaller kinematic disturbances (measured by the maximum departurefrom a symmetric rotation curve, normalized to the full rotationamplitude) than found in a complete sample of non-Seyfert spirals inpairs.
| A catalog of far-ultraviolet point sources detected with the fast FAUST Telescope on ATLAS-1
We list the photometric measurements of point sources made by the FarUltraviolet Space Telescope (FAUST) when it flew on the ATLAS-1 spaceshuttle mission. The list contains 4698 Galactic and extragalacticobjects detected in 22 wide-field images of the sky. At the locationssurveyed, this catalog reaches a limiting magnitude approximately afactor of 10 fainter than the previous UV all-sky survey, TDl. Thecatalog limit is approximately 1 x 10-14 ergs A sq cm/s,although it is not complete to this level. We list for each object theposition, FUV flux, the error in flux, and where possible anidentification from catalogs of nearby stars and galaxies. Thesecatalogs include the Michigan HD (MHD) and HD, SAO, the HIPPARCOS InputCatalog, the Position and Proper Motion Catalog, the TD1 Catalog, theMcCook and Sion Catalog of white dwarfs, and the RC3 Catalog ofGalaxies. We identify 2239 FAUST sources with objects in the stellarcatalogs and 172 with galaxies in the RC3 catalog. We estimate thenumber of sources with incorrect identifications to be less than 2%.
| The large-scale distribution of late-type galaxies between Virgo and the Great Wall
Neutral hydrogen data are presented for 88 of the Virgo Cluster Cataloggalaxies thought on morphological grounds to lie in the background ofthe cluster. We confirm that the morphological assignment of clustermembership works quite well; very few of the 'background' galaxies arein fact at cluster redshifts. The resulting sample of redshifts, alongwith optical redshifts from the literature, allow us to explore thelarge-scale distribution of galaxies in the space between the LocalSupercluster and the Great Wall. Galaxies in a larger window around theVirgo Cluster, but at redshifts between Virgo and the Great Wall, have afairly low average number density, but the distribution is far fromuniform: Some portions resemble voids, but in other portions galaxiescan be assigned to clouds or filaments of appreciable size (sometimescontaining bound groups). We investigate the luminosity function inhigh- and low-density regions of our galaxy sample, which excludes theVirgo Cluster proper. We find no significant difference. However, ourselection procedures are insensitive to galaxies of very low surfacebrightness, which have been reported to be more abundant in low-densityregions. The average probability of a line of sight intersecting theoptical disk of our sample galaxies is derived separately for the VirgoSupercluster region (redshifts below 3500 km/s) and for the regionbehind (out to 10,000 km/s). The number density ratio of Ly-alpha forestlines to galaxies is larger by a factor of order 10 in the far(low-density) region than in the near. A survey of recent literature ongalaxy redshifts uncovers a new candidate, MCG 0-32-16, for the lowestredshift absorption line.
| The X-ray spectra of galaxies. I - Spectral FITS of individual galaxies and X-ray colors
The X-ray spectra of normal galaxies is investigated systematically byusing the Imaging Proportional Counter (IPC) data in the Einstein databank. In addition to the standard model fitting technique, X-ray colorsare introduced in order to extract spectral information from the fainterX-ray sources. Spectral parameters for 43 galaxies and X-ray colors for127 galaxies are presented.
| An X-ray catalog and atlas of galaxies
An X-ray catalog and atlas of galaxies observed with the EinsteinObservatory imaging instruments (IPC and HRI) are presented. The catalogcomprises 493 galaxies, including targets of pointed observations, andRSA or RC2 galaxies serendipitously included in Einstein fields. A totalof 450 of these galaxies were imaged well within the instrumentalfields, resulting in 238 detections and 2123 sigma upper limits. Theother galaxies were either at the edge of the visible field of view orconfused with other X-ray sources. For these a rough measure of theirX-ray emission is also given. The atlas shows X-ray contour maps ofdetected galaxies superposed on optical photographs and givesazimuthally averaged surface brightness profiles of galaxies detectedwith a high signal-to-noise ratio.
| The Einstein Observatory Extended Medium-Sensitivity Survey. II - The optical identifications
The optical identifications are presented of the Einstein ExtendedMedium-Sensitivity Survey (EMSS), including the methodology used tooptically identify the EMSS sources and the uncertainties involved withthat process. The optical properties of the classes of X-ray, optical,and radio data for each of the identified and, as yet, unidentifiedsources of the survey are described. A new class of X-ray emitters,cooling flow galaxies, is proposed. The criteria used to determinewhether the proposed optical counterpart to the X-ray source is aplausible identification are described. Plausibility is based on theoptical classification of the counterpart, e.g., AGN, cluster, G star,and the X-ray-to-optical flux ratios previously observed for theseclasses of X-ray emitters. Two independent schemes of opticalclassification of the counterparts are used to check the plausibility ofthese identifications; one is based on moderate-resolution opticalspectroscopy, and the other, on inferred X-ray luminosity and theoverall energy distribution.
| An optical catalog of extragalactic emission-line objects similar to quasi-stellar objects
A catalog of 935 galaxies which have optical properties similar to thoseof QSOs is given. A subsidiary table of cross-identifications enablesthe reader to relate the name of a given object to its coordinate name.Most of the objects appear to be nonstellar. The majority, more than700, have redshifts z = 0.2 or less, and have mostly been classified asSeyfert galaxies, N systems, or radio galaxies. The Hubble diagram forall of the objects with z = 0.2 or less is shown. The redshiftdistribution peaks at z = 0.025, but there are about 200 powerful radiogalaxies in the extended tail of the distribution which have z greaterthan 0.2. There is a separate and distinct peak in the redshiftdistribution at z = 0.06.
| The Einstein Observatory Extended Medium-Sensitivity Survey. I - X-ray data and analysis
This paper presents the results of the analysis of the X-ray data andthe optical identification for the Einstein Observatory ExtendedMedium-Sensitivity Survey (EMSS). The survey consists of 835serendipitous sources detected at or above 4 times the rms level in 1435imaging proportional counter fields with centers located away from theGalactic plane. Their limiting sensitivities are about (5-300) x 10 tothe -14th ergs/sq cm sec in the 0.3-3.5-keV energy band. A total area of778 square deg of the high-Galactic-latitude sky has been covered. Thedata have been analyzed using the REV1 processing system, which takesinto account the nonuniformities of the detector. The resulting EMSScatalog of X-ray sources is a flux-limited and homogeneous sample ofastronomical objects that can be used for statistical studies.
| A catalogue of Seyfert galaxies.
Not Available
| IRAS observations of galaxies in the Virgo cluster area
IRAS data on 196 galaxies in the area of the Virgo Cluster arepresented. The data derive from combining all available surveyobservations for each object and therefore achieve greater sensitivitythan the IRAS Point Source Catalog (PSC). The enhanced sensitivityallows 78 galaxies to be detected at 12 microns, 82 at 25 microns, 139at 60 microns, and 135 at 100 microns, compared to 16, 23, 88, and 95detections listed in the PSC. From the blue compact dwarf galaxy sample,23 and 19 objects are detected at 60 and 100 microns, compared to threeand two detections listed in the PSC. The emission in three close pairsof galaxies which are reported as single sources in the PSC areseparated here. These statistics demonstrate the importance andpotential of a detailed examination of IRAS data, especially forpossibly resolved sources and, in particular, for galaxies out toredshifts of 0.008 or galaxies with D(25) of 3 arcmin or greater.
| 21 centimeter line width distances of cluster galaxies and the value of H0
Locally calibrated blue and infrared Tully-Fisher (TF) relations areapplied to an 82 percent complete sample of 81 Sab-Sm galaxies which arebona fide members of the Virgo Cluster. A nearly unbiased Virgo modulusof 31.60 + or - 0.15 can be derived in perfect agreement withindependent recent determinations. It is shown that the blue TF andinfrared TF relations give almost identical distance moduli from anyselected Virgo subsample. The intrinsic scatter about the two TFrelations is 0.7 mag, considerably larger than the observed scatter inthe UMa Cluster and in 10 more distant clusters. Distance determinationof these clusters therefore can be achieved only by fitting the upperenvelopes of their TF relations onto the blue and infrared upperenvelopes of the Virgo Cluster. The resulting distances define a linearexpansion law with a small scatter. The present cluster data require H0= 56.6 + or - 0.9 km/s/Mpc.
| X-ray-selected AGNs near bright galaxies
Among the numerous low-redshift low-luminosity X-ray sources discoveredwith the Einstein Observatory, ten AGNs were identified that areprojected within three optical diameters of bright (V less than 18)foreground galaxies. These AGNs near galaxies have significantly higherredshifts than the sample as a whole. This discovery is interpreted interms of gravitational 'microlensing' in which stars in the foregroundgalaxy have significantly brightened the X-ray emission from thesehigher redshift AGNs, allowing their detection. It is suggested thatmicrolensing may be responsible for a significant alteration of theinherent QSO luminosity function.
| Studies of the Virgo Cluster. II - A catalog of 2096 galaxies in the Virgo Cluster area.
The present catalog of 2096 galaxies within an area of about 140 sq degapproximately centered on the Virgo cluster should be an essentiallycomplete listing of all certain and possible cluster members,independent of morphological type. Cluster membership is essentiallydecided by galaxy morphology; for giants and the rare class of highsurface brightness dwarfs, membership rests on velocity data. While 1277of the catalog entries are considered members of the Virgo cluster, 574are possible members and 245 appear to be background Zwicky galaxies.Major-to-minor axis ratios are given for all galaxies brighter than B(T)= 18, as well as for many fainter ones.
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