Contents
Images
Upload your image
DSS Images Other Images
Related articles
Radio emission from AGN detected by the VLA FIRST survey
Using the most recent (April 2003) version of the VLA FIRST survey radiocatalog, we have searched for radio emission from >2800 AGN takenfrom the most recent (2001) version of the Veron-Cetty and Veron AGNcatalog. These AGN lie in the 9033 square degrees of sky alreadycovered by the VLA FIRST survey. Our work has resulted in positivedetection of radio emission from 775 AGN of which 214 are new detectionsat radio wavelengths.Tables 3 and 4 are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/416/35
| 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.
| Are all radio galaxies genuine ellipticals?
Classical double radio sources are believed to be powered by a strongrelativistic jet due to the presence of a rapidly spinning black hole inthe center of a giant E galaxy formed by the merging of two galaxies. Ifthis is true, no radio source should have been found in spiral or S0galaxies. A number of radio S0s have been reported, but most of them areprobably misclassified Es. However, our own observations confirm thatNGC 612 is an S0 although it is associated with the FR II radio sourcePKS 0131-36. We conclude that S0s can be classical radio sources, butthat such occurences are extremely rare. Partly based on observationsobtained with the ESO 3.6 m telescope, La Silla, Chile.
| 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 Age-dependent Luminosities of the Red Giant Branch Bump, Asymptotic Giant Branch Bump, and Horizontal Branch Red Clump
Color-magnitude diagrams of globular clusters usually exhibit aprominent horizontal branch (HB) and may also show features such as thered giant branch (RGB) bump and the asymptotic giant branch (AGB) bump.Stellar evolution theory predicts that the luminosities of thesefeatures will depend on the metallicity and age of the cluster. Wecalculate theoretical lines of 2-12 Gyr constant age RGB bumps and AGBbumps in the DeltaV^HB_Bump-[Fe/H] diagram, which shows the brightnessdifference between the bump and the HB as a function of metallicity. Inorder to test the predictions, we identify giant branch bumps in newHubble Space Telescope color-magnitude diagrams for eight SMC clusters.First, we conclude that the SMC cluster bumps are RGB bumps. The datafor clusters younger than ~6 Gyr are in fair agreement with ourpredictions for the relative age-dependent luminosities of the HB andRGB bump. The DeltaV^HB_Bump data for clusters older than ~6 Gyrdemonstrate a less satisfactory agreement with our calculations. Weconclude that ~6 Gyr is the lower bound to the age of clusters for whichthe Galactic globular cluster, age-independent DeltaV^HB_Bump-[Fe/H]calibration is valid. Application of the DeltaV^HB_Bump-[Fe/H] diagramto stellar population studies is discussed.
| An Unusual Radio Galaxy in Abell 428: A Large, Powerful FR I Source in a Disk-dominated Host
We report the discovery of a powerful (~1024 h^{-2}75{WHz}^{-1} at 20 cm) FR I radio source in a highly flatteneddisk-dominated galaxy. Half the radio flux from this source isconcentrated within the host galaxy, with the remainder in a pair ofnearly symmetrical lobes of total extent ~200 kpc nearly perpendicularto the disk. Traditional wisdom maintains that powerful, extended radiosources are found only in ellipticals or recent merger events. We reportB, R, J, and K imaging, optical spectroscopy, a rotation curve, an IRASdetection, and a VLA 20 cm image for this galaxy, 0313-192. The opticaland near-infrared images clearly show a disk. We detect apparent spiralarms in a deep B-band exposure, and a dust lane from a higher resolutionB-band image. The reddened nucleus is consistent with extinction by asimilar dust lane. The optical spectrum suggests a central AGN and showssome evidence of a starburst, with both the AGN and central starlightappearing substantially reddened (perhaps by the optical dust lane).From analysis of the extended line emission in [O III] and H alpha , wederive a rotation curve consistent with an early-type, dusty spiral seenedge-on. From the IRAS detection at 60 and 100 mu m, we find that theratio of far-infrared to radio flux places this object firmly as a radiogalaxy (i.e., the radio emission is not powered by star formation). Theradio structure suggests that the radio source in this galaxy is relatedto the same physical mechanisms that are present in jet-fed powerfulradio sources, and that such powerful, extended sources can (albeitextremely rarely) occur in a disk-dominated host.
| 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.
| Radio Identifications of Extragalactic IRAS Sources
Extragalactic sources detected at λ= 60 microns were selectedfrom the IRAS Faint Source Catalog, Version 2 by the criterion S_60microns_ >= S_12_ microns. They were identified by positioncoincidence with radio sources stronger than 25 mJy at 4.85 GHz in the6.0 sr declination band 0^deg^ < δ < +75^deg^ (excluding the0.05 sr region 12^h^40^m^< α < 14^h^40^m^, 0^deg^<+5^deg^) and with radio sources stronger than 80 mJy in the 3.4 sr areao^h^ <α < 2o^h^, -40^deg^ < δ < 0^deg^ (plus theregion 12^h^40^m^ < α < 14^h^40^m^, 0^deg^<δ<+5^deg^). Fields containing new candidate identifications weremapped by the VLA at 4.86 GHz with about 15" FWHM resolution. Difficultcases were confirmed or rejected with the aid of accurate (σ ~ 1")radio and optical positions. The final sample of 354 identifications in{OMEGA} = 9.4 sr is reliable and large enough to contain statisticallyuseful numbers of radio-loud FIR galaxies and quasars. The logarithmicFIR radio flux ratio parameter q can be used to distinguish radiosources powered by "starbursts" from those powered by "monsters."Starbursts and normal spiral galaxies in a λ = 60 micronflux-limited sample have a narrow (σ_q_ = 0.14 +/- 0.01) qdistribution with mean = 2.74 +/- 0.01, and none have "warm"FIR spectra [α(25 microns, 60 microns) < 1.5]. The absence ofradio- quiet (but not completely silent) blazars indicates that nearlyall blazars become optically thin at frequencies v<~100 GHz.Nonthermal sources with steep FIR/optical spectra and dusty-embeddedsources visible only at FIR and radio wavelengths must be very rare.
| The Hubble type of the double lobe radio galaxy NGC 5972.
We found in the literature a single example of a spiral galaxyassociated with a classical extended double lobe radio source: NGC 5972classified as an S0-a by Lauberts (1982). We show that it is rather an Egalaxy which may possibly be the result of a merger event. It has anemission line spectrum typical of a Seyfert 2 galaxy.
| Galaxy structures in the Hercules region
216 redshifts have been obtained in a region of 981 sq deg south of theHercules supercluster. 172 of these redshifts are of galaxies withmpg less than or equal to 15.1, 110 of which had no previousvelocity measurement. 44 new redshifts are of galaxies fainter thanmpg = 15.1. With these new data we have been able to define asample in a vast region (approximately 1700 sq deg) around Herculeslimited to mpg less than or equal to 15.1 with a velocitycompleteness of 81.5%. 189 galaxies have been morphologically classifiedso that all galaxies in the sample with known velocity now also haveknown morphology. The magnitude limited sample, including 556 galaxies,is then used to identify and describe galaxy structures in the region.We find that the overdense volume is small, that its overall appearanceis that of a coral branch floating in a sea of nothing and that earlyand late type galaxies defined different structures.
| UGC galaxies stronger than 25 mJy at 4.85 GHz
UGC galaxies in the declination band +5 to +75 deg were identified byposition coincidence with radio sources stronger than 25 mJy on theGreen Bank 4.85 GHz sky maps. Candidate identifications were confirmedor rejected with the aid of published aperture-synthesis maps and new4.86 GHz VLA maps having 15 or 18 arcsec resolution, resulting in asample of 347 nearby radio galaxies plus five new quasar-galaxy pairs.The radio energy sources in UGC galaxies were classified as 'starbursts'or 'monsters' on the basis of their infrared-radio flux ratios, infraredspectral indices, and radio morphologies. The rms scatter in thelogarithmic infrared-radio ratio q is not more than 0.16 for starburstgalaxies selected at 4.85 GHz. Radio spectral indices were obtained fornearly all of the UGC galaxies, and S0 galaxies account for adisproportionate share of the compact flat-spectrum (alpha less than0.5) radio sources. The extended radio jets and lobes produced bymonsters are preferentially, but not exclusively, aligned within about30 deg of the optical minor axes of their host galaxies. The tendencytoward minor-axis ejection appears to be independent of radio-sourcesize and is strongest for elliptical galaxies.
| Radio identifications of UGC galaxies - Starbursts and monsters
New and previously published observational data on galaxies withdeclination less than +82 deg from the Uppsala General Catalog (Nilson,1973) are compiled in extensive tables and characterized in detail.Optical positions are confirmed by measurement of Palomar Sky Survey Oprints, and radio identifications for 176 galaxies are made on the basisof 1.4-GHz Green Bank sky maps or 1.49-GHz observations obtained withthe C configuration of the VLA in November-December 1986; contour mapsbased on the latter observations are provided. Radio-selected andIR-selected galaxy populations are found to be similar (and distinctfrom optically selected populations), and three radio/IR criteria aredeveloped to distinguish galaxies powered by starbursts from those withsupermassive black holes or other 'monster' energy sources.
|
Submit a new article
Related links
Submit a new link
Member of following groups:
|
Observation and Astrometry data
Catalogs and designations:
|
