The Hamburg/RASS Catalogue of optical identifications. Northern high-galactic latitude ROSAT Bright Source Catalogue X-ray sources
We present the Hamburg/RASS Catalogue (HRC) of optical identificationsof X-ray sources at high-galactic latitude. The HRC includes all X-raysources from the ROSAT Bright Source Catalogue (RASS-BSC) with galacticlatitude |b| >=30degr and declination delta >=0degr . In thispart of the sky covering ~ 10 000 deg2 the RASS-BSC contains5341 X-ray sources. For the optical identification we used blue Schmidtprism and direct plates taken for the northern hemisphere Hamburg QuasarSurvey (HQS) which are now available in digitized form. The limitingmagnitudes are 18.5 and 20, respectively. For 82% of the selectedRASS-BSC an identification could be given. For the rest either nocounterpart was visible in the error circle or a plausibleidentification was not possible. With ~ 42% AGN represent the largestgroup of X-ray emitters, ~ 31% have a stellar counterpart, whereasgalaxies and cluster of galaxies comprise only ~ 4% and ~ 5%,respectively. In ~ 3% of the RASS-BSC sources no object was visible onour blue direct plates within 40\arcsec around the X-ray sourceposition. The catalogue is used as a source for the selection of(nearly) complete samples of the various classes of X-ray emitters.
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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.
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Structures of small-size radio galaxies in clusters
We present high resolution maps of a sample of radio galaxies belongingto Abell clusters, showing linear size less than or approximately 20kpc, i.e. completely embedded within the optical galaxy. These radiogalaxies were unresolved or only sligtly resolved in previousinterferometric observations. Most of the sources are resolved at thepresent resolution. Radio maps of all the resolved sources are given.The correlation of the linear size versus the total radio power at 1.4GHz is derived for radio galaxies belonging to clusters and is comparedwith the results found in a non-cluster sample. The size of clustersources is slightly smaller on average than that of non-cluster ones,but the difference is not statistically significant. The tailedstructure, typical of cluster radio galaxies of large size, found inapproximately 24% of the sources of the present sample. This percentageis higher than in a non-cluster sample, but lower than ina clustersample of radio galaxies with larger size. Tailed radio galaxies aremostly located at the cluster centers, the smallest ones beingidentified with the brightest cluster member. Stripping of the hotinterstellar medium is suggested to be present in these galaxies.
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The kinematics of Abell clusters
Velocity histograms, galaxy positions, and velocity dispersions arepresented for 69 nearby Abell clusters. The shape of the cumulativedistribution for R = 1 or more clusters does not match the predictionsof standard CDM models for any biasing parameter b. The only modelsconsistent with the median and maximum dispersions of the sample arethose of b about 1.6-2.0 and in which clusters are identified in threedimensions. Velocity dispersions of high-redshift systems appearfundamentally different from those of nearby clusters. The mediandispersion of the subset of 25 cD clusters is similar to that of non-cDsystems. A substantial fraction of the cD galaxies have velocitiessignificantly different from the mean of their parent clusters. Three ofthese have 4 s or more measured redshifts. These last two resultssuggest that the formation of cD galaxies is dominated by the local,rather than global, cluster environment.
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A 20 CM VLA survey of Abell clusters of galaxies. I - Distance class of not greater than 3 clusters
Nearby Abell clusters of distance class of not greater than 3 arestudied based on 20-cm VLA observations, Westerbork Synthesis RadioTelescope results, and Einstein Observatory X-ray data. No significantcorrelation is found between the 20-cm radio power and X-ray luminosity,and no evidence is found that regular-type clusters are statisticallymore likely to be radio loud than irregular-type clusters. A weakcorrelation is noted between X-ray-cooling mass-accretion rates andradio powers for central dominant galaxies in cooling-flow clusters,suggesting that either cooling accretion directly fuels the centralengine and/or cooling flows strongly interact with the radio plasma.
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The marginal gravitational lensing
Gravitational lenses with four types of marginality are investigated.The first type concerns a definite lens able to split light rays and arange of source positions, yielding a pair of amplified images close tomerging. The second is a range of lenses barely able to split images.The third and fourth types of marginality concern two-component lensesin which one component plays the role of a background (e.g., a clusteror similar gravitational field) that affects the images split by thesecond component (e.g., a galactic or stellar gravitational field). Theorder-of-magnitude estimates of characteristic image separations andamplifications for the pair of brightest images produced by the fourkinds of marginal lenses are presented.
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Profiles of clusters of galaxies - Cosmological scenarios versus observations
The present study of rich clusters of galaxies by means of comparisonsof N-body simulations with observations identifies protoclusters inlarge scale simulations which represent a wide range of cosmologicalscenarios (including hybrid ones). The density profiles of the simulatedclusters are found to be similar, irrespective of initial conditions.The existence of a universal profile suggests that violent relaxation isefficient in the erasing of initial condition traces from the clusterprofile during first collapse, although the secondary infall does notsignificantly affect it. Observed luminosity profiles are obtained for asample of 27 Abell clusters, and a comparison with theoretical massdensity profiles shows good agreement. Cluster density profiles arejudged to be poor indicators of the origin of the large-scale structurein the universe.
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Correlation between the radio power and the X-ray luminosity for rich clusters of galaxies
On the basis of data from a nearly complete sample of 140 Abell clustersof galaxies with z in the range of 0.02-0.075, the correlation betweenthe clusters' radio and X-ray luminosities is studied. Only a weakindirect correlation is found between these parameters. Consideration isgiven to hypotheses pertaining to the interaction between radio galaxiesand the intergalactic gas of clusters.
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Relative velocities of multiple-nucleus galaxies
Relative velocities of the components in 17 multiple-nucleus galaxieshave been measured. Combining these results with previously publisheddata, it was found that the distribution of velocity differences isconsistent with random sampling from a gaussian with a disperison ofabout 800 km/s, typical of that found in rich clusters. These resultsare compatible with Merritt's recent (1984) suggestion that the majorityof the secondary components in multiple-nucleus systems are not bound tothe central galaxy and will not merge on a dynamical time-scale.
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WSRT radio observations at 1.4 GHz of 32 Abell clusters of distance class 3 and 4
A survey of 61 Abell clusters was carried out at 1.4 GHz with theWesterbork Synthesis Radio Telescope. In this paper radio and opticaldata on 23 clusters of distance class 3 and on 9 clusters of distanceclass 4 are presented. Only the radio sources identified with galaxieslikely to be cluster members are considered here. A finding chart foreach radio galaxy and contour maps for the interesting structures areprovided.
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The Trivariate / Radio Optical X-Ray / Luminosity Function CD Galaxies - Part Two - the Fuelling of Radio Sources
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1983A&A...125..223V&db_key=AST
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A catalog of morphological types in 55 rich clusters of galaxies
Data are presented from a study of 55 rich clusters of galaxies. Thedata include positions, morphological types, estimated total magnitudes,bulge sizes, and ellipticities for about 6000 galaxies, as determinedfrom high scale photographic plates. Data reduction procedures aredescribed, and a brief analysis of cluster richness, which indicatesthat Abell richness classes are only rough indicators of total clustermembership, is included.
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A comprehensive study of 12 very rich clusters of galaxies. I. Photometric technique and analysis of the luminosity function.
Not Available
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Radial velocities for galaxies in 11 clusters.
Not Available
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