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A new sample of large angular size radio galaxies. III. Statistics and evolution of the grown population
We present in this paper a detailed study of a new sample of largeangular size FR I and FR II radio galaxies and compare the properties ofthe two classes. As expected, a pure morphology based distinction of FRIs and FR IIs corresponds to a break in total radio power. The radiocores in FR Is are also weaker than in FR IIs, although there is not awell defined break power. We find that asymmetry in the structure of thesample members must be the consequence of anisotropies in the mediumwhere the lobes expand, with orientation playing a minor role. Moreover,literature data and our observations at kiloparsec scales suggest thatthe large differences between the structures of FR I and FR II radiogalaxies must arise from the poorly known central kiloparsec region oftheir host galaxies. We analyze the sub-sample of giant radio galaxies,and do not find evidence that these large objects require higher corepowers. Our results are consistent with giant radio galaxies being theolder population of normal FR I and FR II objects evolving in lowdensity environments. Comparing results from our sample with predictionsfrom the radio luminosity function we find no evidence of a possible FRII to FR I evolution. Moreover, we conclude that at z 0.1, one outof four FR II radio sources has a linear size above 500 kpc, thus beingin an advanced stage of evolution (for example, older than 10 Myrassuming a jet-head velocity of 0.1c). Radio activity seems to be ashort-lived process in active galaxies, although in some casesrecurrent: five objects in our sample present signs of reactivation intheir radio structures.
| A new sample of large angular size radio galaxies. II. The optical data
We constructed and presented in the first paper of this series a newsample of 84 large angular size radio galaxies by selecting from theNRAO VLA Sky Survey objects with angular size >=4arcmin , declinationabove +60deg and total flux density at 1.4 GHz >= 100 mJy.In this paper we present optical spectra and images of those galaxiesassociated with the radio emission for which no redshift was known priorto our observations. Optical counterparts have been identified for all(but one) members of the sample. After our observations, a reliablespectroscopic redshift is available for 67 objects (80%) from thesample. This paper, the second of a series of three, contributes toincrease the number of well-defined samples of radio galaxies with amplespectroscopic information.
| A new sample of large angular size radio galaxies. I. The radio data
We present a new sample of 84 large angular size radio galaxies selectedfrom the NRAO VLA Sky Survey. Radio sources with declination above+60deg, total flux density greater than 100 mJy at 1.4 GHzand angular size larger than 4arcmin have been selected and observedwith the VLA at 1.4 and 4.9 GHz. The radio observations attempt toconfirm the large angular size sources and to isolate the core emissionfor optical identification. In this paper, the first of a series ofthree, we present radio maps of 79 sources from the sample and discussthe effects of the selection criteria in the final sample. 37 radiogalaxies belong to the class of giants, of which 22 are reported in thispaper for the first time. Complete Fig.~2 is only available inelectronic form at http://www.edpsciences.org
| The peculiar motions of early-type galaxies in two distant regions - II. The spectroscopic data
We present the spectroscopic data for the galaxies studied in the EFARproject, which is designed to measure the properties and peculiarmotions of early-type galaxies in two distant regions. We have obtained1319 spectra of 714 early-type galaxies over 33 observing runs on 10different telescopes. We describe the observations and data reductionsused to measure redshifts, velocity dispersions and the Mgb and Mg_2Lick linestrength indices. Detailed simulations and intercomparison ofthe large number of repeat observations lead to reliable error estimatesfor all quantities. The measurements from different observing runs arecalibrated to a common zero-point or scale before being combined,yielding a total of 706 redshifts, 676 velocity dispersions, 676 Mgblinestrengths and 582 Mg_2 linestrengths. The median estimated errors inthe combined measurements are Delta cz=20 km s^-1, Delta sigma sigma=9.1 per cent, Delta Mgb Mgb=7.2 per cent and Delta Mg_2=0.015 mag.Comparison of our measurements with published data sets shows nosystematic errors in the redshifts or velocity dispersions, and onlysmall zero-point corrections to bring our linestrengths on to thestandard Lick system. We have assigned galaxies to physical clusters byexamining the line-of-sight velocity distributions based on EFAR andZCAT redshifts, together with the projected distributions on the sky. Wederive mean redshifts and velocity dispersions for these clusters, whichwill be used in estimating distances and peculiar velocities and to testfor trends in the galaxy population with cluster mass. The spectroscopicparameters presented here for 706 galaxies combine high-quality data,uniform reduction and measurement procedures, and detailed erroranalysis. They form the largest single set of velocity dispersions andlinestrengths for early-type galaxies published to date.
| 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.
| The peculiar motions of early-type galaxies in two distant regions. III - The photometric data
We present R-band CCD photometry for 776 galaxies observed in the EFARproject. The photometry is compared with photoelectric data, showingthat a common zero-point good to better than 1 per cent and a precisionof 0.03 mag per zero-point have been achieved. We give the circularlyaveraged surface brightness profiles and the photometric parameters ofthe 762 program galaxies, D(n) diameters, half-luminosity radii, totalmagnitudes, and average effective surface brightnesses. More than 80percent of the profiles have a global S/N ratio larger than 300. Theextrapolation needed to derive total magnitudes is less than 10 percentfor 80 percent of the fits. More than 80 percent of the galaxies havemean effective surface brightness larger than the observed skybrightness. In 90 percent of the profiles the estimate of thecontamination of the sky by the galaxy light is less than 1 percent. Wederive total magnitudes and half-luminosity radii to better than 0.15mag and 25 percent, respectively, for 90 percent of our sample. Incontrast, external comparisons show that data in the literature can bestrongly affected by systematic errors due to large extrapolations,small radial range, sky subtraction errors, seeing effects, and the useof a simple R exp 1/4 fit. The resulting errors can easily amount tomore than 0.5 mag in the total magnitudes and 50 percent in thehalf-luminosity radii.
| The Peculiar Motions of Early-Type Galaxies in Two Distant Regions. I. Cluster and Galaxy Selection
The EFAR project is a study of 736 candidate elliptical galaxies in 84clusters lying in two regions, toward Hercules-Corona Borealis andPerseus-Pisces-Cetus, at distances cz ~ 6000-15,000 km s^-1^. In thispaper (the first of a series), we present an introduction to the EFARproject and describe in detail the selection of the clusters andgalaxies in our sample. Fundamental data for the galaxies and clustersare given, including accurate new positions for each galaxy andredshifts for each cluster. The galaxy selection functions aredetermined by using diameters measured from Schmidt sky survey imagesfor 2185 galaxies in the cluster fields. Future papers in this serieswill present the spectroscopic and photometric observations of thissample, investigate the properties of the fundamental plane forelliptical galaxies, and determine the large- scale peculiar velocityfields in these two regions of the universe.
| A radio-optical survey of the North Ecliptic CAP
The Cambridge Low Frequency Synthesis Telescope has been used to surveya region ~=7x7 deg^2 about the North Ecliptic Cap at 151 MHz with aresolution of 70x77 arcsec^2. The resulting radio source catalogue of400 sources is complete to a peak flux density limit of 120 mJy beam^-1.Using the Cambridge APM we have searched for identifications on thePalomar Sky Survey plate 550 which covers much of the survey area, andwe list the 157 sources with one or more optical objects within 15arcsec of the radio position.
| Groups of Galaxies in the ROSAT North Ecliptic Pole Survey
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995ApJ...449..422H&db_key=AST
| Photoelectric and CCD photometry of E and S0 galaxies
We present BR photoelectric photometry for 352 E and S0 galaxies thatare part of a large survey of the properties and peculiar motions ofgalaxies in distant clusters. Repeat measurements show our internalerrors to be 2-3 percent in B and R and 1-2 percent in B-R. Comparisonsof BR and BVR reductions for 10 galaxies also observed in V show smallsystematic errors due to differences between the spectral energydistributions of stars and galaxies. External comparisons with B-Vcolors in the literature confirm that these colors are good to 1percent. We also describe R-band CCD observations for 95 of the galaxiesand place these on a BR photometric system for photoelectric and CCDphotomerry, with a common zero-point good to better than 1 percent. Wefind the rms precision of both our photoelectric and CCD R magnitudes tobe 2-3 percent for galaxies as faint as R = 15.
| Redshifts of forty-three radio sources
Redshift measurements are presented for the optical counterparts of 43radio sources and for three radio-quiet galaxies in the Coma cluster.Eleven of the counterparts are optical identifications of individualradio galaxies lying in the direction of the Coma cluster or theHercules cluster, eight sources are quasars, and the remaining 24sources are radio galaxies from various surveys. The equipment,observations, and measurements are described in detail. It is noted thatfive of the radio galaxies not associated with the Coma or the Herculescluster have head-tail radio structures.
| A pencil-beam survey of radio sources at 178 MHz
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1969MNRAS.145..181C&db_key=AST
| Identifications of radio sources with bright galaxies
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1967MNRAS.135..231C&db_key=AST
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