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Rotational Widths for Use in the Tully-Fisher Relation. I. Long-Slit Spectroscopic Data
We present new long-slit Hα spectroscopy for 403 noninteractingspiral galaxies, obtained at the Palomar Observatory 5 m Hale telescope,which is used to derive well-sampled optical rotation curves. Becausemany of the galaxies show optical emission features that aresignificantly extended along the spectrograph slit, a technique wasdevised to separate and subtract the night sky lines from the galaxyemission. We exploit a functional fit to the rotation curve to identifyits center of symmetry; this method minimizes the asymmetry in thefinal, folded rotation curve. We derive rotational widths using bothvelocity histograms and the Polyex model fit. The final rotational widthis measured at a radius containing 83% of the total light as derivedfrom I-band images. In addition to presenting the new data, we use alarge sample of 742 galaxies for which both optical long-slit and radioH I line spectroscopy are available to investigate the relation betweenthe H I content of the disks and the extent of their rotation curves.Our results show that the correlation between those quantities, which iswell established in the case of H I-poor galaxies in clusters, ispresent also in H I-normal objects: for a given optical size, starformation can be traced farther out in the disks of galaxies with largerH I mass.
| 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.
| The Einstein Two-Sigma Catalog: Silver Needles in the X-Ray Haystack
To facilitate the study of X-ray sources fainter than those contained inthe Einstein Medium-Sensitivity Survey (EMSS), we have constructed a newcatalog of sources and fluctuations exceeding 2 σ significance in2520 high-latitude Einstein IPCC images. We have employed various teststo validate our source-search algorithm for both high- and low-significance sources, and to identify and remove the small number ofspurious sources induced by our detection procedure. Based on the knownvignetting and background characteristics of the IPC and the measured X-ray log N-log S relation, we have modeled the number of real sourcesexpected in the catalog in order to evaluate its statistical propertiesbelow 4 σ significance. Our modeling suggests that ~13,000 sourcesin the catalog are real celestial X-ray sources, an increase of ~9100over the number found in previous analyses of the same IPC images. Wefind that not only is the reliability of the Two-Sigma Catalog afunction of source significance σ, it is a function of off-axisangle on the detector as well. The application of differentsignal-to-noise thresholds at different off-axis angles thus enables oneto tune the reliability of the catalog. The chief motivation forstudying large numbers of faint X-ray sources is to search for possiblenew components of the cosmic X-ray background. To select out realcelestial X-ray sources in the Two-Sigma Catalog, we apply astronomicalcatalogs at other wavelengths as filters. For example, thecross-correlation of the Two-Sigma Catalog with catalogs from surveys ofthe radio and infrared sky has yielded large samples of faint X-raysources that are ~90% reliable. Optical spectroscopy of 77 unidentifiedfaint X-ray sources has turned up several surprises, illustrating themerits of selecting X-ray sources using a variety of methods: high-redshift quasars (one at z = 4.30), which are absent in the EMSS, X-ray-luminous (L_x_ ~ 10^43^ ergs s^-1^) radio-loud elliptical galaxies withoptical spectra devoid of emission lines, and infrared-bright activegalactic nuclei whose optical spectra are dominated by starburst galaxyfeatures. Follow-up observations are scheduled to determine whether anyof these types of objects represent a previously unrecognized componentof the X-ray background.
| 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.
| UBV photometry of galaxies in group and their neighborhood. The Geller-Huchra group GH 3.
Not Available
| Peculiar velocities of clusters in the Perseus-Pisces supercluster
Photometry is presented for spiral galaxies in five clusters of galaxiesin the direction of the Perseus-Pisces supercluster. The 21 cmobservations of these galaxies by Giovanelli et al. (1982, 1986) areemployed to measure distances of these clusters by means of theTully-Fisher relation. Most of these are in fact more distant than thesupercluster and have peculiar velocities averaging 400 km/s. This isbroadly in agreement with the earlier result of Willick (1990, 1991) whoanalyzed a large field sample. A local model in which galaxies areinfalling to two mass concentrations, one in Perseus-Pisces and one inHydra-Centaurus, fits the data at least as well as bulk flow. Thepresent data leave both these possibilities open.
| A 21 CM survey of the Pisces-Perseus supercluster. IV - Addenda to the declination zone 21.5 deg to 33.5 deg
Using the 305-m Arecibo telescope, 21-cm line data on 472 disk galaxiesin the Pisces-Perseus supercluster have been obtained. Data on galaxiessmaller than 1 arcmin are presented for the declination strips coveredin previous studies (Giovanelli and Haynes, 1985 and Giovanelli et al.,1986). Tables of the 21-cm line data for this region are presented.
| A VLA 20 CM survey of poor groups of galaxies
The paper reports on VLA 20 cm observations of an extensive sample ofgalaxies in 139 poor groups. These groups, composed of galaxies down tothe limit of the Zwicky et al. (CGCG) catalog, were chosen using apercolation algorithm set at a high surface-density threshold.Approximately 50 percent of the groups have measured redshifts. Thesegroups were surveyed using a 'snapshot' mode of the VLA with aresolution of about 13 arcsec. Analysis of the resulting radio andoptical properties reveals that the presence of a nearby companiongalaxy has an important role in generating radio emission in a galaxy.CCD observations of two radio-loud, disturbed galaxies with companionsare presented and are used to discuss models of radio-source production.Nine tailed radio galaxies are found in the poor groups, which is muchmore than had been expected from previous work on rich clusters and fromtheoretical models. The paper discusses previous statistical biases andproposes a method for bending head-tail sources in poor groups. From theconfinement of extended radio features associated with tailed sources,the presence of a substantial intracluster medium that should radiatesignificantly at soft-X-ray energies is predicted.
| Radio emission of Abell clusters of galaxies at 102.5 MHz
Results are presented of investigations of rich clusters of galaxiesfrom the Abell catalog with a distance class equal to or less than 3,based on observations at 102.5 MHz with the Pushchino phased antennaarray. The radio luminosities and spectral indices of the clusters aredetermined, and the 102.5 MHz luminosity function of these clusters ofgalaxies is derived for the range 10 to the 25th to 10 to the 27th W/Hz.These findings are compared with optical and X-ray data, and thecomparisons indicate correlations of the radio parameters (luminosityand spectral index) with the richness, morphological type, and X-rayluminosity of the clusters. It is shown that these statistical relationscan be qualitatively explained by the influence of the hot intraclustergas on the evolution of active member radio galaxies.
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