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Evolution of Star-forming and Active Galaxies in Nearby Clusters
We have used optical spectroscopy to investigate the active galaxypopulations in a sample of 20 nearby Abell clusters. The targets wereidentified on the basis of 1.4 GHz radio emission, which identifies themas either active galactic nuclei (AGNs) or galaxies forming stars atrates comparable to or greater than that of the Milky Way. The spectrawere used to characterize the galaxies via their emission and absorptionfeatures. The spectroscopy results reveal a significant population ofstar-forming galaxies with large amounts of nuclear dust extinction.This extinction eliminates bluer emission lines such as [O II] from thespectra of these galaxies, meaning their star formation could easily beoverlooked in studies that focus on such features. Around 20% of thecluster star-forming galaxies have spectra of this type. The radialdistributions of active galaxies in clusters show a strong segregationbetween star-forming galaxies and AGNs, with star-forming galaxiesbroadly distributed and AGNs preferentially in the cluster cores. Theradial distribution of the dusty star-forming galaxies is more centrallyconcentrated than the star-forming galaxies in general, which arguesthat they are a consequence of some cluster environmental effect.Furthermore, we note that such galaxies may be identified using their4000 Å break strengths. We find that discrepancies in reportedradio luminosity functions for AGNs are likely the result ofclassification differences. There exists a large population of clustergalaxies whose radio fluxes, far-infrared fluxes, and optical magnitudessuggest their radio emission may be powered by stars yet whose spectralack emission lines. Understanding the nature of these galaxies iscritical to assessing the importance of AGNs in the radio luminosityfunction at low luminosities. We also find that regardless of thispopulation, the crossover point where the radio luminosity function iscomposed equally of star-forming galaxies and AGNs occurs at lowerluminosities in clusters than in the field. This is likely a simpleconsequence of the reduction in star formation in cluster galaxies andthe morphological mix in clusters compared with the field.Based in part on observations obtained with the Apache Point Observatory(APO) 3.5 m telescope, which is owned and operated by the AstrophysicalResearch Consortium.
| The Radio Galaxy Populations of Nearby Northern Abell Clusters
We report on the use of the NRAO VLA Sky Survey (NVSS) to identify radiogalaxies in 18 nearby Abell clusters. The listings extend from the coresof the clusters out to radii of 3 h-175 Mpc, whichcorresponds to 1.5 Abell radii and approximately 4 orders of magnitudein galaxy density. To create a truly useful catalog, we have collectedoptical spectra for nearly all of the galaxies lacking public velocitymeasurements. Consequently, we are able to discriminate between thoseradio galaxies seen in projection on the cluster and those that are inactuality cluster members. The resulting catalog consists of 329 clusterradio galaxies plus 138 galaxies deemed foreground or backgroundobjects, and new velocity measurements are reported for 273 of theseradio galaxies. The motivation for the catalog is the study of galaxyevolution in the cluster environment. The radio luminosity function is apowerful tool in the identification of active galaxies, as it isdominated by star-forming galaxies at intermediate luminosities andactive galactic nuclei (AGNs) at higher luminosities. The flux limit ofthe NVSS allows us to identify AGNs and star-forming galaxies down tostar formation rates less than 1 Msolar yr-1. Thissensitivity, coupled with the all-sky nature of the NVSS, allows us toproduce a catalog of considerable depth and breadth. In addition tothese data, we report detected infrared fluxes and upper limits obtainedfrom IRAS data. It is hoped that this database will prove useful in anumber of potential studies of the effect of environment on galaxyevolution. Based in part on observations obtained with the Apache PointObservatory 3.5 m telescope, which is owned and operated by theAstrophysical Research Consortium (ARC).
| 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.
| The galaxy cluster Abell 426 (Perseus). A catalogue of 660 galaxy positions, isophotal magnitudes and morphological types
We present a homogeneous catalogue of galaxies in the field of thenearby galaxy cluster A 426 (Perseus) based on a survey of digitisedSchmidt plates taken with the Tautenburg 2 m telescope in the B band.Accurate positions, morphological types, B25 isophotalmagnitudes, angular radii and position angles are given for 660 galaxieswithin a field of about 10 square-degrees, centred on alpha = 3() h 21()min, delta = 41degr 33' (J2000). When available, the radial velocity andthe most common name taken from NED or PGC are included. The cataloguecomprises galaxies brighter than B25~19.5. The estimatedlimit of completeness is B25~18. Two thirds of the galaxiesare published for the first time. The galaxy positions are measured witha mean accuracy of 0farcs5 , the photometric accuracy is of the order of0.1 to 0.2 mag depending on image crowding and galaxy shape.Morphological properties were evaluated from the visual inspections ofboth deep images obtained from the digital co-addition of a large numberof plates and higher-resolution images from single plates taken undergood seeing conditions. The superimposed images unveil faint structuresdown to mu_B ~ 27 mag arcsec(-2) . The catalogue is applied to a studyof statistical properties of the galaxies in A 426: projecteddistribution of morphological types, segregation of morphological types,position of the cluster centre, distribution of galaxy position angles,type-dependent luminosity functions, and total B-luminosity of the thecluster. In agreement with previous studies, we find a relativespiral-deficiency in the central region (r <~ 30'). The percentage ofidentified S+Irr increases, however, increases from 30% in the centre tomore than 50% in the outer parts. The projected distributions of early-and late-type galaxies are not co-centred. The total luminosity of allsupposed member galaxies in the surveyed area is estimated to(6.5+/-0.9)\ 10(12) x h50(-2) blue solar luminosities. We donot analyse in detail possible substructures in the projecteddistribution of galaxies. However, we found a pronounced clump ofgalaxies at alpha (J2000.0) = 3() h20fm4 , delta (J2000.0) = 43degr4 ',which is shown to be a background cluster at z~ 0.050. The catalogue isonly 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 } \fnmsep \thanks{ Based onobservations made with the 2\,m telescope of the ThüringerLandessternwarte Tautenburg, Germany, and with the 2.2\,m telescope ofthe German-Spanish Astronomical Centre, Calar Alto, Spain.
| 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.
| Apparent magnitudes of galaxies behind the Milky Way
There are many Infrared Astronomy Satellite (IRAS) Uppsala GeneralCatalogue of Galaxies (UGC) and IRAS/Catalogue of Galaxies and ofClusters of Galaxies (CGCG) galaxies with measured redshifts in theMilky Way region at absolute value of b less than 15 deg. We compare themagnitudes of these galaxies with those of IRAS/UGC and IRAS/CGCGgalaxies located at b = 30 deg to 45 deg having similar redshift values.Eighteen redshifts of the latter objects were newly measured by us. Thebrightnesses of the galaxies systematically decrease with Galacticlatitude at the Milky Way region. It is shown that IRAS galaxies withincz less than 10000 km/sec are mostly detected in the regions behind theMilky Way with N(H I) less than 5 x 1021/sq cm if theredshifts are measured down to 21 mag in blue magnitude.
| Isophotal shapes of early-type galaxies. II - The Perseus Cluster
We present the results of an isophotal shape analysis of a sample of 91early-type galaxies belonging to the Perseus Cluster, using CCD R and Vimages obtained in very good seeing conditions. This survey uncoversfine details in the structure of a large percentage of these objects,including disks, bars and even spiral arms, so that a large variety ofmorphological types is proposed. A very conservative upper limit for thepercentage of galaxies of the whole sample showing no deviations fromellipticity is given to be 20 percent. A lower limit for the detectionof bars among galaxies newly classified as S0's or spirals is about 30percent.
| The dynamics of rich clusters of galaxies. II - The Perseus cluster
The dynamics of the Perseus cluster are analyzed using self-consistentequilibrium analytical models. Using existing data in the literatureplus new radial velocities reported here, composite surface density andvelocity dispersion profiles are derived. These profiles have beencompared with dynamical models described by Kent and Gunn (1982). Thebest fit suggest the presence of a significant degree of anisotropy inthe velocity distribution: galaxy orbits are constrained to pass withina radius of seven cluster radii, or 1.3 deg of the cluster center. ForHubble constant = 50, a core radius of 340 kpc 11 arcmin and a mass tovisual light ratio M/L = 300 are found. Using these results, X-rayobservations of the intracluster medium in Perseus are reanalyzed. Apreviously noted discrepancy between the observed temperature of the hotgas and the cluster velocity dispersion is reduced but not eliminated. Acooling accretion flow previously deduced to exist in this cluster isshown to extend to only about one-third of the cluster radius.
| Redshift-magnitude bands and the evolution of galaxies. I - New observations
Well-defined samples of galaxy redshifts and magnitudes for the Perseusand A1367 clusters are obtained from a combination of new and existingobservations. For the Perseus cluster, identifications, 1950 positions,distance from cluster center in degrees, mp and V(6)magnitudes, redshifts corrected for earth orbital and galactic rotation,and comments are provided. Information for the 50 central A1367 galaxiesincludes identification, mp, redshift and redshift source,morphology, and comments.
| Dynamics of the Perseus Cluster of Galaxies
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1971ApJ...168..321C&db_key=AST
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