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Double Nuclei and ``TDGs": Colliding or Activity of Nucleus Monster?
It is known that among active galaxies (AG) with strong emission lines (UV-galaxies, Sy 1 and Sy2, Markarian and Kazarian galaxies,Radio-galaxies, QSO's host galaxies and so on) there are large per centof objects with double and multiple nucleus. The common sizes andvolumes of these nuclei are on the order of a few hundred parsecs orkilo-parsecs. In fact these are not double galaxies or clusters ofgalaxies as many of astronomers believe, but just the complicatednucleus of AG. The problem is: what are the nature and the birth ofthese objects? There are in fact two basic suppositions in the subject:(a) The complicated nuclei are the result of merging or colliding of twoor more galaxies, or: (b) They are the results of nuclear activity. Theresults of detailed spectroscopic observations of a number of "tidalgalaxies", carried out with the 5m Palomar telescope, 2.6m telescope ofAmbartsumian Byurakan astrophysical observatory (multi-pupilspectroscopy with Tiger receiver) and 6m telescope of SpecialAstrophysical observatory of Russia are presented. It is shown that inmany cases the "tidal dwarf galaxies "(or actually complicatednucleus) are the result of galactic nuclear activity.
| 1.65-μm (H -band) surface photometry of galaxies - VIII. The near-IR κ space at z =0
We present the distribution of a statistical sample of nearby galaxiesin the κ -space (κ 1 ~logM , κ 2~logI e 3 M /L , κ 3 ~logM /L ).Our study is based on near-IR (H -band: λ =1.65μm)observations, for the first time comprising early- and late-typesystems. Our data confirm that the mean effective dynamicalmass-to-light ratio M /L of the E+S0+S0a galaxies increases withincreasing effective dynamical mass M , as expected from the existenceof the Fundamental Plane relation. Conversely, spiral and Im/BCDgalaxies show a broad distribution in M /L with no detected trend of M/L with M , the former galaxies having M /L values about twice largerthan the latter, on average. For all the late-type galaxies, the M /Lincreases with decreasing effective surface intensity I e ,consistent with the existence of the Tully-Fisher relation. Theseresults are discussed on the basis of the assumptions behind theconstruction of the κ -space and their limitations. Our study iscomplementary to a previous investigation in the optical (B -band:λ =0.44μm) and allows us to study wavelength dependences ofthe galaxy distribution in the κ -space. As a first result, wefind that the galaxy distribution in the κ 1 -κ2 plane reproduces the transition from bulgeless tobulge-dominated systems in galaxies of increasing dynamical mass.Conversely, it appears that the M /L of late-types is higher (lower)than that of early-types with the same M in the near-IR (optical). Theorigins of this behaviour are discussed in terms of dust attenuation andstar formation history.
| Radio Sources and Star Formation in the Local Universe
Galaxies from the entire Uppsala Galaxy Catalog (UGC) have beenidentified with 4583 radio sources stronger than 2.5 mJy at 1.4 GHz fromthe NRAO VLA Sky Survey (NVSS). The complete sample of 3398 galaxiesbrighter than mp=14.5 in the area defined byδ>-2deg30' and |b|>20degyielded the UGC/NVSS sample of 1966 radio sources. Their dominant energysources were classified as stars (85%) or active galactic nuclei (15%).The luminosity function of star-forming galaxies agrees well with thefar-infrared (FIR) luminosity function converted to 1.4 GHz by theFIR/radio correlation. The spectral power density of star-forminggalaxies is USF=(1.53+/-0.07)×1019 WHz-1 Mpc-3 (statistical errors only) ifH0=70 km s-1 Mpc-1. We used a modelconsistent with the observed FIR/radio correlation to estimate thecorresponding star formation rate density within the pastτ~3×108 yr; it isρSF(M>0.1Msolar)~0.018 Msolaryr-1 Mpc-3. The radio sources in star-forminggalaxies may be evolving even at moderately low redshifts (z~0.1).
| The UZC-SSRS2 Group Catalog
We apply a friends-of-friends algorithm to the combined Updated ZwickyCatalog and Southern Sky Redshift Survey to construct a catalog of 1168groups of galaxies; 411 of these groups have five or more members withinthe redshift survey. The group catalog covers 4.69 sr, and all groupsexceed the number density contrast threshold, δρ/ρ=80. Wedemonstrate that the groups catalog is homogeneous across the twounderlying redshift surveys; the catalog of groups and their membersthus provides a basis for other statistical studies of the large-scaledistribution of groups and their physical properties. The medianphysical properties of the groups are similar to those for groupsderived from independent surveys, including the ESO Key Programme andthe Las Campanas Redshift Survey. We include tables of groups and theirmembers.
| 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 new list of extra-galactic radio jets
A catalogue of extra-galactic jets is very useful both in observationaland theoretical studies of active galaxies. With the use of new powerfulradio instruments, the detailed structures of very compact or weak radiosources are investigated observationally and many new radio jets aredetected. In this paper, we give a list of 661 radio sources withdetected radio jets known to us prior to the end of December 2000. Allreferences are collected for the observations of jets in radio, IR,optical, UV and X-ray wave-bands. Table 1 and references to Table 1 areonly available in electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/381/757
| X-ray luminosities of galaxies in groups
We have derived the X-ray luminosities of a sample of galaxies ingroups, making careful allowance for contaminating intragroup emission.The LX:LB and LX:LFIRrelations of spiral galaxies in groups appear to be indistinguishablefrom those in other environments, however the elliptical galaxies fallinto two distinct classes. The first class is central-dominant groupgalaxies, which are very X-ray luminous and may be the focus of groupcooling flows. All other early-type galaxies in groups belong to thesecond class, which populates an almost constant band ofLX/LB over the range9.8
| 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
| Arcsecond Positions of UGC Galaxies
We present accurate B1950 and J2000 positions for all confirmed galaxiesin the Uppsala General Catalog (UGC). The positions were measuredvisually from Digitized Sky Survey images with rms uncertaintiesσ<=[(1.2")2+(θ/100)2]1/2,where θ is the major-axis diameter. We compared each galaxymeasured with the original UGC description to ensure high reliability.The full position list is available in the electronic version only.
| On the local radio luminosity function of galaxies. II. Environmental dependences among late-type galaxies
Using new extensive radio continuum surveys at 1.4 GHz (FIRST and NVSS),we derive the distribution of the radio/optical and radio/NIR luminosity(RLF) of late-type (Sa-Irr) galaxies (m_p<15.7) in 5 nearby clustersof galaxies: A262, Cancer, A1367, Coma and Virgo. With the aim ofdiscussing possible environmental dependences of the radio properties,we compare these results with those obtained for relatively isolatedobjects in the Coma supercluster. We find that the RLF of Cancer, A262and Virgo are consistent with that of isolated galaxies. Conversely weconfirm earlier claims that galaxies in A1367 and Coma have their radioemissivity enhanced by a factor ~ 5 with respect to isolated objects. Wediscuss this result in the framework of the dynamical pressure sufferedby galaxies in motion through the intra-cluster gas (ram-pressure). Wefind that the radio excess is statistically larger for galaxies in fasttransit motion. This is coherent with the idea that enhanced radiocontinuum activity is associated with magnetic field compression. TheX-ray luminosities and temperatures of Coma and A1367 imply that thesetwo clusters have significantly larger intracluster gas density than theremaining three studied ones, providing a clue for explaining the higherradio continuum luminosities of their galaxies. Multiple systems in theComa supercluster bridge (with projected separations smaller than 300kpc) have radio luminosities significantly larger than isolatedgalaxies. Table~1 is 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/Abstract.html}
| Groups of galaxies. III. Some empirical characteristics.
Not Available
| 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.
| An Einstein X-Ray Survey of Optically Selected Galaxies. I. Data
We present the results of a complete Einstein imaging proportionalcounter X-ray survey of optically selected galaxies from theShapley-Ames Catalog, the Uppsala General Catalogue, and the EuropeanSouthern Observatory Catalog. Well-defined optical criteria are used toselect the galaxies, and X-ray fluxes are measured at the opticallydefined positions. The result is a comprehensive list of X-ray detectionand upper limit measurements for 1018 galaxies. Of these, 827 haveeither independent distance estimates or radial velocities. Associatedoptical, redshift, and distance data have been assembled for thesegalaxies, and their distances come from a combination of directlypredicted distances and those predicted from the Faber-Burstein GreatAttractor/Virgocentric infall model. The accuracy of the X-ray fluxeshas been checked in three different ways; all are consistent with thederived X-ray fluxes being of <=0.1 dex accuracy. In particular,there is agreement with previously published X-ray fluxes for galaxiesin common with a 1991 study by Roberts et al. and a 1992 study byFabbiano et al. The data presented here will be used in further studiesto characterize the X-ray output of galaxies of various morphologicaltypes and thus to enable the determination of the major sourcescontributing to the X-ray emission from galaxies.
| Kopf-Schwanz-Radioquellen. Proben fur das intergalaktische Medium.
Not Available
| 1.65μm (H-band) surface photometry of galaxies. II. Observations of 297 galaxies with the TIRGO 1.5m telescope.
We present near-infrared H-band (1.65μm) surface photometry of 297galaxies (mostly) in the Coma Supercluster obtained with the ArcetriNICMOS3 camera, ARNICA, mounted on the Gornergrat Infrared Telescope.Magnitudes and diameters within the 21.5mag/arcsec^2^ isophote,concentration indices, and total H magnitudes are derived. Combiningthese observations with those obtained similarly using the Calar Altotelescopes (Paper I, 1996A&AS..120..489G) we find a strong positivecorrelation between the near-infrared concentration index and the galaxyH-band luminosity, and we analyze the consequent dependence ofnear-infrared growth-curves on H-band luminosity.
| 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.
| The fundamental plane of early-type galaxies: stellar populations and mass-to-light ratio.
We analyse the residuals to the fundamental plane (FP) of ellipticalgalaxies as a function of stellar-population indicators; these are basedon the line-strength parameter Mg_2_ and on UBVRI broad-band colors, andare partly derived from new observations. The effect of the stellarpopulations accounts for approximately half the observed variation ofthe mass-to-light ratio responsible for the FP tilt. The residual tiltcan be explained by the contribution of two additional effects: thedependence of the rotational support, and possibly that of the spatialstructure, on the luminosity. We conclude to a constancy of thedynamical-to-stellar mass ratio. This probably extends to globularclusters as well, but the dominant factor would be here the luminositydependence of the structure rather than that of the stellar population.This result also implies a constancy of the fraction of dark matter overall the scalelength covered by stellar systems. Our compilation ofinternal stellar kinematics of galaxies is appended.
| A Catalog of Stellar Velocity Dispersions. II. 1994 Update
A catalog of central velocity dispersion measurements is presented,current through 1993 September. The catalog includes 2474 measurementsof 1563 galaxies. A standard set of 86 galaxies is defined, consistingof galaxies with at least three reliable, concordant measurements. It issuggested that future studies observe some of these standard galaxies sothat different studies can be normalized to a consistent system. Allmeasurements are reduced to a normalized system using these standards.
| ROSAT Observations of Five Poor Galaxy Clusters with Extended Radio Sources
We present the results of deep ROSAT PSPC observations of the poorclusters MKW2, N79-299A, S49-128, S49-132, and S49-140. These poorclusters all contain extended radio sources, generally with a bent,head- tail (HT) morphology. It had been previously thought that HTsshould only be found in rich clusters, which have sufficiently highintracluster medium (ICM) densities and velocity dispersions foreffective ram pressure bending of the radio jets. We have found that theX-ray emission associated with these poor clusters is generally quiteclumpy and asymmetrical. Often, the clumps are associated with subgroupsor individual galaxies, as well as with extended regions around theradio sources. Our results also indicate that there is a continuum ofX-ray properties from poor to rich clusters. In many respects, poorclusters seem to be a low-mass extension of rich clusters. We find thatthese poor clusters have baryon fractions ranging from 1% to 25%. Also,the radio sources within these clusters are probably thermally confinedby the ICM. Although four of our clusters have central X-ray luminosityexcesses, the implied cooling times are longer than a Hubble time. Weinterpret the central X-ray luminosity excesses as unresolved galaxyemission. We hypothesize that these poor clusters have recentlycollapsed out of large, loose clouds of galaxies. We believe that manyof the poor cluster properties are understandable in light of thishypothesis. First, four of these five clusters are embedded withinlarger Zwicky clusters. This may indicate that these large Zwickyclusters act as "incubators" of poor clusters. Second, the observedflat, broad velocity distributions may reflect the velocities associatedwith the larger-scale systems from which we believe that these poorclusters have collapsed. Third, some of these galaxies (such as NGC4061, within N79-299A) show signs of interactions with neighboringgalaxies with large relative velocities (~850 km/s). Fourth, theobserved ICM densities, coupled with velocity distributions which aresuggestive of unrelaxed systems, and the peculiar velocities of theradio galaxies may explain the ram pressure bending of the radio jets inthe HTs.
| ROSAT Observations of 5 Poor Galaxy Clusters with Extended Radio Sources
We present the results of ROSAT pointed observations of the poorclusters MKW2, N79--299A, S49--128, S49--132 and S49--140. These poorclusters all contain extended radio sources, generally with a bent,head-tail (HT) morphology. It has been thought that HTs should only befound in rich clusters, which have sufficiently high intracluster medium(ICM) densities and velocity dispersions for effective ram pressurebending of the radio jets. Yet, at least a dozen HTs are known to existin poor clusters. This situation has motivated us to perform ROSATpointed observations of the ICM in 5 poor clusters with HTs. We havefound that the X-ray emission associated with these clusters isgenerally quite clumpy and asymmetric. Often, the clumps are associatedwith subgroups of galaxies and individual galaxies, as well as withradio sources. We hypothesize that many poor clusters have recentlycollapsed out of large, loose clouds of galaxies. We believe thatseveral of our results are understandable in light of this hypothesis.First, the observed ICM densities in these clusters, as well as theirunusually broad velocity distributions, provide enough ram pressure tobend the radio jets. Second, some of these galaxies (such as NGC 4061,within N79--299A) show signs of interactions with neighboring galaxies.Third, 4 of these 5 clusters are embedded within larger Zwicky clusters.This may indicate that Zwicky's nearby, open clusters are in fact realsystems and act as ``incubators'' of poor clusters. Fourth, the flat,broad velocity distributions may reflect the velocities associated withthe larger scale systems from which we hypothesize that these poorclusters have collapsed. We believe that this hypothesis has sufficientmerit to warrant further investigation.
| Why do head-tail sources exist in poor clusters of galaxies?
In a continuing study of nearby (z approximately 0.02-0.05) radiosources in poor clusters of galaxies, we obtained Very Large Array (VLA)observations of four head-tail (HT) sources as probes of theintracluster environments: NGC 742, NGC 1044, NGC 4061, and NGC 7503.NGC 742 apparently has a companion, NGC 741, in the midst of itsextended tail structure. NGC 7503 and NGC 4061 have horseshoe shapesvery similar to the archetypal HT radio galaxy, NGC 1265. Thesestructures are remarkable because the sources are found in poor groups,where both the average density of the intracluster medium (ICM) and thevelocities of the galaxies (thus the ram pressures) are supposedly muchlower than in the rich clusters. Yet these poor groups have narrow-angletail (NAT) sources with the same general morphologies as those in richclusters. There is not much difference between our poor-cluster NATsources and rich-cluster NAT sources, in terms of jet radii ofcurvature, jet opening angles, internal ram pressures within the jets,jet luminosity as a fraction of total source luminosity, and ICMdensities. It appears that the HT phenomenon is remarkably similarbetween the poor clusters and the rich clusters because the localconditions near these sources within their clusters are similar. An ICMdensity typical of that found in poor clusters (approximately10-4/cc and a galaxy velocity typical of the rich clusters(approximately 600 km/s) provide sufficient ICM ram pressure to bendradio jets into NAT morphologies. One explanation for the high relativevelocities of the poor cluster HT galaxies is that these clusters aredynamically young and are still collapsing.
| A CCD survey of galaxies. III. Observations with the Loiano 1.5m telescope.
Continuing a CCD survey of galaxies belonging or projected onto the Comaand Hercules Superclusters and to the A262, Virgo and Cancer clusters,we present isophote maps and photometric profiles in the Johnson systemof 127 galaxies (126 taken in the V, 28 of which also in the B band, oneonly in B). For the objects in common we compare our results with thosein the RC3.
| Head tail sources in poor clusters of galaxies
Head tail sources in poor clusters of galaxies have been studied usingthe VLA at wavelengths of 6 cm and 20 cm. Four sources (NGC 742, NGC1044, NGC 4061 and NGC 7503) were selected from a larger sample fordetailed study. These sources represent an exceptional opportunity tostudy radio jets and their interaction with the cluster environment, indetail, because of their proximity (z ~ 0.02 to 0.04). NGC 4061 and NGC7503 exhibit narrow-angle-tail (NAT) morphologies similar to the classicrich cluster NAT, NGC 1265. NGC 742 has a complex morphology while NGC1044 shows a wide-angle-tail (WAT) morphology. The NAT morphologies arebelieved to be the result of the intracluster medium (ICM) rampressures. The poor cluster NATs are thus remarkable because the poorcluster ICM ram pressure is expected to be much lower, in general, thanin rich clusters. Comparisons of the results of the poor cluster sourceswith those of NGC 1265 should reveal much about the radio source andcluster environment interaction. Most of the parameters calculated suchas jet luminosity as a fraction of total source luminosity, jet openingangle, jet radius of curvature and the ICM density surrounding thesources are quite similar between NGC 1265 and the poor cluster sources.This is a very surprising result and we conclude that ICM densitiestypical of poor clusters and a galaxy relative velocity ~ 1000 km s(-1)provide sufficient ram pressure to bend radio jets into NATmorphologies. Spectral indices and polarization structures have beencompared between the rich and poor clusters and are found to be similaras well. The spectral indices in the poor cluster sources (alpha_ {jet}~ -0.6 and alpha_ {tail} \approx -0.8) are similar to those of the richcluster sources. The fractional polarizations vary from \sim 10% in thejets to \sim 30%$ in the tails similar to the rich cluster HT sources.The magnetic field structure appears to follow the general structureseen in low luminosity radio sources. The overall result is theremarkable similarity between the HT phenomenon in the rich and poorclusters.
| A revised catalog of CfA1 galaxy groups in the Virgo/Great Attractor flow field
A new identification of groups and clusters in the CfA1 Catalog ofHuchra et al. is presented, using a percolation algorithm to identifydensity enhancements. It is shown that in the resulting catalog,contamination by interlopers is significantly reduced. The Schechterluminosity function is redetermined, including the Malmquist bias.
| Why Do Head Tail Sources Exist In Poor Clusters Of Galaxies?
In a continuing study of radio sources in poor clusters of galaxies, wehave obtained VLA observations of four head-tail sources as probes ofthe intracluster environments: NGC 742, NGC 1044, NGC 4061, and NGC7503. These sources represent an exceptional opportunity for the studyof radio sources (and radio jets in particular). They are very nearby (z~ 0.02 to 0.04) and thus can be examined in great detail, much like NGC1265 in Perseus. The four sources contain some remarkable structures.NGC 742 apparently has a companion, NGC 741, in the midst of itsextended tail structure. NGC 7503 has a horseshoe shape very similar toNGC 1265. The NGC 4061 source maintains a very linear structure out toequal distances on either side of the galaxy center, where the lobes aresharply `swept back.' These structures are remarkable because thesources are found in poor groups, where both the density of the ICM andthe velocities of the galaxies (thus the ram pressures) are supposedlymuch lower than in the rich clusters. Yet these poor groups havenarrow-angle-tail sources (NATs) with the same general characteristicsas those in rich clusters. Our calculations indicate that there is notmuch difference between the poor cluster sources and NGC 1265 in ICMdensities, jet luminosity as a fraction of total source luminosity, andradii of curvature of the jets. These are very surprising results. Whilethe jets of two sources (NGC 4061 and NGC 7503) appear to have roughlytwice the opening angle of the NGC 1265 jet (which suggests lesserpressure-confinement in poor clusters), most of our evidence pointstoward remarkably similar environments for rich and poor cluster jets.
| UGC galaxies stronger than 25 mJy at 4.85 GHz
UGC galaxies in the declination band +5 to +75 deg were identified byposition coincidence with radio sources stronger than 25 mJy on theGreen Bank 4.85 GHz sky maps. Candidate identifications were confirmedor rejected with the aid of published aperture-synthesis maps and new4.86 GHz VLA maps having 15 or 18 arcsec resolution, resulting in asample of 347 nearby radio galaxies plus five new quasar-galaxy pairs.The radio energy sources in UGC galaxies were classified as 'starbursts'or 'monsters' on the basis of their infrared-radio flux ratios, infraredspectral indices, and radio morphologies. The rms scatter in thelogarithmic infrared-radio ratio q is not more than 0.16 for starburstgalaxies selected at 4.85 GHz. Radio spectral indices were obtained fornearly all of the UGC galaxies, and S0 galaxies account for adisproportionate share of the compact flat-spectrum (alpha less than0.5) radio sources. The extended radio jets and lobes produced bymonsters are preferentially, but not exclusively, aligned within about30 deg of the optical minor axes of their host galaxies. The tendencytoward minor-axis ejection appears to be independent of radio-sourcesize and is strongest for elliptical galaxies.
| Head-tail radio sources in poor clusters of galaxies : VLA Observations and comparisons to rich cluster HTs.
Not Available
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