|Radio continuum spectra of galaxies in the Virgo cluster region|
New radio continuum observations of galaxies in the Virgo cluster regionat 4.85, 8.6, and 10.55 GHz are presented. These observations arecombined with existing measurements at 1.4 and 0.325 GHz. The sampleincludes 81 galaxies where spectra with more than two frequencies couldbe derived. Galaxies that show a radio-FIR excess exhibit centralactivity (HII, LINER, AGN). The four Virgo galaxies with the highestabsolute radio excess are found within 2° of the centerof the cluster. Galaxies showing flat radio spectra also host activecenters. There is no clear trend between the spectral index and thegalaxy's distance to the cluster center.Figure 3 is only available in electronic form athttp://www.edpsciences.orgTable 3 is only available in electronic form at the CDS via anonymousftp to cdsarc.u-strasbg.fr (126.96.36.199) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/418/1
|The origin of wide-angle tailed radio galaxies|
To investigate the origins of wide-angle tailed radio sources (WATs), wehave compiled a sample of these systems in Abell clusters for whichX-ray data exist. Contrary to conventional wisdom, the WATs are found tobe significantly displaced from the X-ray centroids of their hostclusters. The bends in the radio jets of WATs are found to be orientedpreferentially such that they point directly away from or toward thecluster centre, with more of the former than the latter. If thismorphology is attributed to ram pressure, then the WATs are on primarilyradial orbits, with more approaching the X-ray centroid than receding.There is also some evidence that the incoming WATs are on averagefurther from the X-ray centroid than the outgoing ones. All of theseobservations strongly support a scenario in which WATs are created incluster mergers.
|Radio-loud active galaxies in the northern ROSAT All-Sky Survey. IV. Properties of sources stronger than 100 mJy at 5 GHz|
We present multi-frequency radio data for 741 extragalactic sources witha 5 GHz integrated flux density of > 100 mJy. These sources have beenselected from a cross-correlation of an early ROSAT All-Sky Surveysource list with a list of compact radio sources of the 5 GHz Green Banknorthern sky survey (RGB sample). The majority of sources werequasi-simultaneously observed with the Effelsberg 100-m telescope at 11cm, 6 cm, and 2.8 cm. We have determined the spectrum, size and linearpolarization properties of these sources. We compare the radio data withROSAT measurements and optical data. We find that the X-ray selectedradio sources, when compared with unbiased radio source samples, are onaverage slightly more compact, show a higher fractional polarization, ahigher absolute rotation measure (RM), and have flatter spectra.Absolute RMs are larger for steep spectrum than for flat spectrumsources and for extended than for compact sources. The average redshiftincreases with the radio flux density, which indicates that the X-rayselected radio sources have a larger fraction of beamed radio emission.All source characteristics of the sample are in accordance with presentunification schemes for AGN, where X-ray selected sources are preferablelooked at face on. Tables~1 and 2 are only available in electronic format the CDS via anonymous ftp to cdsarc.u-strasbg.fr (188.8.131.52) orvia http://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 (184.108.40.206) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
|The Cluster Dynamics, X-Ray Emission, and Radio Galaxies in Abell 578 = Abell 1569|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1997AJ....114.1711G&db_key=AST
|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.
|Search for High Rotation Measures in Extragalactic Radio Sources I. Multi-Channel Observations at 10 GHz|
Multi-channel polarimetry has been performed to detect high rotationmeasure (RM) at 3 cm using the Nobeyama 45-m telescope. The high RMcandidates of 96 radio sources were selected to be observed, and RMs of35 sources were derived from the observations. Since the four channelsare set contiguously from 2.84 cm to 3.31 cm, |RM| can be deriveduniquely up to 15000 rad m(-2) by this polarimeter. We found that thereexist sources with RM of several thousands rad m(-2) . In fact, 5sources have |RM| > 1000 rad m(-2) . On the other hand, all sourcesobserved are well within this system limits, and therefore we suggestthe observed upper limit of |RM| is around 5000 rad m(-2) forextragalactic radio sources, even taken into account the redshift ofsources.
|The ROSAT AGN content of the 87GB 5 GHz survey: bulk properties of previously optically identified sources.|
The cross-correlation of the source list from the ROSAT All-Sky Surveywith the 5 GHz Green Bank survey yields a list of 2127 objects. Abouttwo thirds of them are optically unidentified. The majority of theobjects with known optical counterparts are quasars and radio galaxies,most of them detected in X-rays for the first time. In this paper wepresent a list of the previously optically identified objects with theirmain characteristics and discuss their general (bulk) properties. Wefind strong correlations between luminosities in the radio, optical, andX-ray bands which differ for quasars and radio galaxies. The fraction offlat radio spectrum sources increases with redshift and ~ 95% of allsources above z = 2 are of that type. In the relatively large group ofblazars, radio selected BL Lacs and highly polarized quasars show verysimilar properties while X-ray selected BL Lacs have markedly differentX-ray to radio flux ratios. The sample is large enough and ofsufficiently high quality to reveal clearly various detection biases andselection effects which strongly influence the physical interpretationof the correlations. Radio follow - up observations for thedetermination of the morphological and spectral properties as well asenvironmental conditions are needed for a statistically reliable studyof the sample. The very large group of sources with low radio fluxesremains to be optically identified.
|The X-ray AGN content of the Molonglo 408 MHz Survey: Bulk properties of previously optically identified sources|
The cross-correlation of a source list from the ROSAT All Sky Surveywith the Molonglo 408 MHz Survey (MRC) yields a calalogue of 549sources. The majority of the objects are quasars and radio galaxies withknown optical counterparts, most of them detected in X-rays for thefirst time. More than one third of the objects are opticallyunidentified. In this paper we will present a discussion of therepresentative properties of the 337 previously optically identifiedactive galactic nuclei (AGN). We find strong correlations betweenluminosities in the radio, optical, and X-ray bands which differ forquasars and radio galaxies. Several of the statistical sourcecharacteristics seem not to support simple unification schemes. However,for many objects some of their key properties like redshift, radiomorphology and environmental conditions are not known yet. The fractionof X-ray detected quasars in the MRC is around 30%, higher than that ofradio galaxies (less tha 8%). It is not currently known which intrinsicproperties are responsible for the X-ray loudness of these radioobjects. We further have evidence for a considerable number of objectsbeing radio- and X-ray loud, but optically very faint.
|A 20 centimeter VLA survey of Abell clusters of galaxies. III - Images and optical identifications|
Radio contour maps, models, and optical identifications for 250 radiogalaxies in Abell clusters of galaxies are presented. Consideration isgiven to the effect of environment on radio galaxies, the evolution ofradio galaxies in rich clusters, and the importance of beaming in acomplete sample of radio galaxies.
|Molonglo Radio Sources in the Directions of Southern Abell Clusters|
We present lists of the radio sources from the 408-MHz MolongloReference Catalogue which have projected separations less than 500kpc(0.33 R_Abell_) from rich southern clusters of galaxies in the newAbell, Corwin & Olowin catalogue. There are 107 such sources in thedirections of 94 clusters for the new southern catalogue, of which weestimate about 27 sources are chance alignments, not associated with thecluster concerned. We also list 89 sources similarly 'coincident' withclusters in the supplementary southern catalogue, and 99 for the revisednorthern catalogue (to the northern declination limit of the MolongloReference Catalogue, +18.5^deg^). We find a stronger concentration ofthe radio sources to the cluster centre than in previous work. Weattribute this to the effects of dominant galaxies at the clustercentres, as revealed by better positional accuracy than for previouslarge-scale radio surveys of clusters.
|A Deep Sky Survey at 3.9-GHZ 7.7-GHZ and 14.4-GHZ|
|The cluster environments of powerful radio galaxies|
Results in the form of the ratio of the spatial cross-correlationamplitude to the autocorrelation amplitude are given as estimates of thelocal galaxy density around about 200 powerful radio sources. Lickgalaxy counts for z of less than 0.1 are extended to z of less than 0.25using deep galaxy samples from UK Schmidt plates. Although thelow-luminosity Fanaroff-Riley class I sources lie in richer clustersthan those of class II, a real scatter in properties is found. Theresults show no statistical evidence for the difference in environmentsuggested to exist between different subclasses of the class II sources.Compact radio sources are found to lie in regions of low galacticdensity.
|Catalogue of unambiguous (Faraday-thin, one-component, spectrum-selected) rotation measures for galaxies and quasars|
This all-sky catalogue of unambiguous rotation measure (from aFaraday-thin, one-component, spectrum selection) for 674 galaxies orquasars has been compiled, ordered, and edited from the availableliterature. All the known applications of the RM distribution towardforeground objects in the Galaxy (i.e., magnetic field in 4 nearbyspiral arms and in 4 nearby interstellar magnetic bubbles) have alsobeen catalogued.
|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.
|Bright radio sources at 178 MHz - Flux densities, optical identifications and the cosmological evolution of powerful radio galaxies|
A revised sample of bright radio sources at 178 MHz is defined in orderto correct the biases introduced into the 3CR catalog by confusion andpartial resolution. The sample is shown to be 96 percent complete to aflux-density limit of 10 Jy for sources smaller than 10 arcmin. The biasof the 3CR catalog against objects of larger angular size is alsoreduced. Optical identifications are presented for 96 percent of thesources, 71 percent with galaxies and 25 percent with quasars. Theradio-galaxy population is found to show strong space-density evolutionfor luminosities in excess of approximately 10 exp 26.5 W/Hz-sr at 178MHz (redshifts greater than or approximately equal to 0.2), while theevolutionary properties of galaxies and quasars of the same luminosityand redshift are very similar.
|Radio observations of Abell clusters and a comparison with certain Einstein observations|
Areas around 70 clusters have been observed at the Arecibo Observatoryprimarily for coordination with about 60 Einstein X-ray sources. Arecibosource coordinates and flux density are tabulated, and someidentifications are made with cataloged radio sources. Statisticalestimates are made of the percentage of cluster sources among allsources in certain areas and to limits on the flux density of 430 MHz.Arecibo and other radio data are compared with the available Einsteindata of seven clusters. Not every Einstein source has a radiocounterpart, and the counterparts may variously be bilobed, tailed, orsingle. A parameter which is proportional to source continuum power at430 MHz ranges over fewer orders of magnitude than the associated sourceX-ray luminosity, with no certain correlation between these parameters.NRAO Green Bank interferometer observations of A401 and A2142 arereported.
|The Faraday rotation measures of extragalactic radio sources|
The rotation measures of 555 extragalactic radio sources are calculatedas a result of a large number of new linear polarization measurementscarried out at several wavelengths. A summary of references for previouspolarization measurements is included, and the procedure for optimizingthe number of unambiguous rotation measures is described.
|Variability of extragalactic sources at 2.7 GHz. II - Flux densities of 550 sources and further evidence for variations|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1977AJ.....82...21B&db_key=AST
|A study of the revised 3C catalogue. I. Confusion and resolution.|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1977A&AS...30..131V&db_key=AST
|Image-tube photography of a complete sample of 4C radio sources|
Image-tube photographs have been obtained in the fields of over 200 4Cradio sources. The incidence of highly variable QSOs is much lower thanthat found among objects in higher-frequency radio surveys; none of the130 fields which were blank to about 20 mag at the epoch of the PalomarSky Survey (1950-1956) now contains an object not exceeding 19.5-20 mag,and of the 35 known QSOs in the sample, only about one-third show achange greater than 0.2 mag since the Sky Survey. There is a negativecorrelation between the amount of variability and the absolute opticalluminosity of the QSOs. Optical identifications for a uniform sample of232 4C sources are summarized; they include some new ones made as aresult of this study.
|Spectra of sources in the NRAO 5000-MHz surveys.|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974AJ.....79.1220C&db_key=AST
|The NRAO 5-GHz radio source survey. III. The 140-ft "strong" source survey.|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972AJ.....77..797P&db_key=AST
|Flux densities, positions, and structures for a complete sample of intense radio sources at 1400 MHz.|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1972AJ.....77..405B&db_key=AST
|Two-dimensional structures of 76 extragalactic radio sources at 1425 MHz.|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971AJ.....76..513F&db_key=AST
|A Determination of the Luminosity Function of Radiogalaxies at 400 and 2700 MHz|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971A&A....15...11M&db_key=AST
|A Statistically Complete Sample of Radio-Sources at 1400 MHz|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971A&A....11..171W&db_key=AST
|Revised spectra for 74 radio sources|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1968MNRAS.141..377M&db_key=AST
|The radio spectra of sources in the Fourth Cambridge Catalogue-III|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1968MNRAS.139..289W&db_key=AST
|The East-West Structure of Radio Sources at 1425 MHz|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1968ApJS...15..203F&db_key=AST