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The ISOPHOT 170 μm Serendipity Survey II. The catalog of optically identified galaxies%
The ISOPHOT Serendipity Sky Survey strip-scanning measurements covering≈15% of the far-infrared (FIR) sky at 170 μm were searched forcompact sources associated with optically identified galaxies. CompactSerendipity Survey sources with a high signal-to-noise ratio in at leasttwo ISOPHOT C200 detector pixels were selected that have a positionalassociation with a galaxy identification in the NED and/or Simbaddatabases and a galaxy counterpart visible on the Digitized Sky Surveyplates. A catalog with 170 μm fluxes for more than 1900 galaxies hasbeen established, 200 of which were measured several times. The faintest170 μm fluxes reach values just below 0.5 Jy, while the brightest,already somewhat extended galaxies have fluxes up to ≈600 Jy. For thevast majority of listed galaxies, the 170 μm fluxes were measured forthe first time. While most of the galaxies are spirals, about 70 of thesources are classified as ellipticals or lenticulars. This is the onlycurrently available large-scale galaxy catalog containing a sufficientnumber of sources with 170 μm fluxes to allow further statisticalstudies of various FIR properties.Based on observations with ISO, an ESA project with instruments fundedby ESA Member States (especially the PI countries: France, Germany, TheNetherlands and the UK) and with the participation of ISAS and NASA.Members of the Consortium on the ISOPHOT Serendipity Survey (CISS) areMPIA Heidelberg, ESA ISO SOC Villafranca, AIP Potsdam, IPAC Pasadena,Imperial College London.Full Table 4 and Table 6 are only available in electronic form at theCDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/422/39
| The Parkes quarter-Jansky flat-spectrum sample. I. Sample selection and source identifications
We present a new sample of quarter-Jansky flat-spectrum radio sourcesselected to search for high-redshift quasars and to study the evolutionof the flat-spectrum quasar population. The sample comprises 878 radiosources selected from the Parkes catalogues with spectral indices alpha5 GHz_2.7 GHz >=-0.4 where Snu ~ nu alpha. The sample covers all right ascensions and the declination rangefrom -80fdg0 to +2fdg5 , excluding low galactic latitudes (mid b mid< 10deg) and the Magellanic Cloud regions. We haveobtained improved radio source positions, firstly to reconfirm themajority of the existing identifications, and secondly, using digitizedsky-survey data and deep B, Gunn-i and Gunn-z CCD-imaging, to findoptical identifications for 223 previously-unidentified sources. Wepresent the final catalogue of 878 flat-spectrum sources: 827 arecompact radio sources identified with galaxies, quasars and BL Lacobjects, 38 have either extended radio structure or are identified withGalactic objects (PN, HII or non-compact radio source), 4 are obscuredby Galactic stars, and 9 (1 per cent of the total sample) remainunidentified. Full Appendices A-D are only available in electronic format http://www.edpsciences.org
| High-resolution radio observations of Seyfert galaxies in the extended 12-μm sample - II. The properties of compact radio components
We discuss the properties of compact nuclear radio components in Seyfertgalaxies from the extended 12-μm AGN sample of Rush et al. Our mainresults can be summarized as follows. Type 1 and type 2 Seyferts producecompact radio components which are indistinguishable in strength andaspect, indicating that their central engines are alike, as proposed bythe unification model. Infrared IRAS fluxes are more closely correlatedwith low-resolution radio fluxes than high-resolution radio fluxes,suggesting that they are dominated by kiloparsec-scale, extranuclearemission regions; extranuclear emission may be stronger in type 2Seyferts. Early-type Seyfert galaxies tend to have stronger nuclearradio emission than late-type Seyfert galaxies. V-shaped extendedemission-line regions, indicative of `ionization cones', are usuallyfound in sources with large, collimated radio outflows. Hidden broadlines are most likely to be found in sources with powerful nuclear radiosources. Type 1 and type 2 Seyferts selected by their IRAS 12-μm fluxdensities have well-matched properties.
| X-ray properties of the Parkes sample of flat-spectrum radio sources: dust in radio-loud quasars?
We investigate the X-ray properties of the Parkes sample offlat-spectrum radio sources using data from the ROSAT All-Sky Survey andarchival pointed PSPC observations. In total, 163 of the 323 sources aredetected. For the remaining 160 sources, 2sigma upper limits to theX-ray flux are derived. We present power-law photon indices in the0.1-2.4 keV energy band for 115 sources, which were determined eitherwith a hardness ratio technique or from direct fits to pointed PSPC dataif a sufficient number of photons were available. The average photonindex is =1.95^+0.13_-0.12 for flat-spectrum radio-loudquasars, =1.70^+0.23_-0.24 for galaxies, and=2.40^+0.12_-0.31 for BL Lac objects. The soft X-ray photonindex is correlated with redshift and with radio spectral index in thesense that sources at high redshift and/or with flat (or inverted) radiospectra have flatter X-ray spectra on average. The results are in accordwith orientation-dependent unification schemes for radio-loud activegalactic nuclei. Webster et al. discovered many sources with unusuallyred optical continua among the quasars of this sample, and interpretedthis result in terms of extinction by dust. Although the X-ray spectrain general do not show excess absorption, we find that low-redshiftoptically red quasars have significantly lower soft X-ray luminositieson average than objects with blue optical continua. The differencedisappears for higher redshifts, as is expected for intrinsic absorptionby cold gas associated with the dust. In addition, the scatter in log(f_x/f_o) is consistent with the observed optical extinction, contraryto previous claims based on optically or X-ray selected samples.Although alternative explanations for the red optical continua cannot beexcluded with the present X-ray data, we note that the observed X-rayproperties are consistent with the idea that dust plays an importantrole in some of the radio-loud quasars with red optical continua.
| The Southern Sky Redshift Survey
We report redshifts, magnitudes, and morphological classifications for5369 galaxies with m_B <= 15.5 and for 57 galaxies fainter than thislimit, in two regions covering a total of 1.70 sr in the southerncelestial hemisphere. The galaxy catalog is drawn primarily from thelist of nonstellar objects identified in the Hubble Space TelescopeGuide Star Catalog (GSC). The galaxies have positions accurate to ~1"and magnitudes with an rms scatter of ~0.3 mag. We compute magnitudes(m_SSRS2) from the relation between instrumental GSC magnitudes and thephotometry by Lauberts & Valentijn. From a comparison with CCDphotometry, we find that our system is homogeneous across the sky andcorresponds to magnitudes measured at the isophotal level ~26 magarcsec^-2. The precision of the radial velocities is ~40 km s^-1, andthe redshift survey is more than 99% complete to the m_SSRS2 = 15.5 maglimit. This sample is in the direction opposite that of the CfA2; incombination the two surveys provide an important database for studies ofthe properties of galaxies and their large-scale distribution in thenearby universe. Based on observations obtained at Cerro TololoInter-American Observatory, National Optical Astronomy Observatories,operated by the Association of Universities for Research in Astronomy,Inc., under cooperative agreement with the National Science Foundation;Complejo Astronomico El Leoncito, operated under agreement between theConsejo Nacional de Investigaciones Científicas de laRepública Argentina and the National Universities of La Plata,Córdoba, and San Juan; the European Southern Observatory, LaSilla, Chile, partially under the bilateral ESO-ObservatórioNacional agreement; Fred Lawrence Whipple Observatory;Laboratório Nacional de Astrofísica, Brazil; and the SouthAfrican Astronomical Observatory.
| The Deep X-Ray Radio Blazar Survey. I. Methods and First Results
We have undertaken a survey, the Deep X-Ray Radio Blazar Survey (DXRBS),of archived, pointed ROSAT Position Sensitive Proportional Counter datafor blazars by correlating the ROSAT WGACAT database with severalpublicly available radio catalogs, restricting our candidate list toserendipitous flat radio spectrum sources (alpha_r <= 0.70, whereS_nu ~ nu^-alpha_r . We discuss our survey methods, identificationprocedure, and first results. Our survey is found to be ~95% efficientat finding flat-spectrum radio-loud quasars (FSRQs; 59 of our first 85identifications) and BL Lacertae objects (22 of our first 85identifications), a figure that is comparable to or greater than thatachieved by other radio and X-ray survey techniques. The identificationspresented here show that all previous samples of blazars (even whentaken together) did not representatively survey the blazar population,missing critical regions of (L_X, L_R) parameter space within whichlarge fractions of the blazar population lie. Particularly important isthe identification of a large population of FSRQs (>~25% of DXRBSFSRQs) with ratios of X-ray to radio luminosity >~10^-6 (alpha_rx<~ 0.78). In addition, as a result of our greater sensitivity, theDXRBS has already more than doubled the number of FSRQs in completesamples with 5 GHz (radio) luminosities between 10^31.5 and 10^33.5 ergss^-1 Hz^-1, and fills in the region of parameter space betweenX-ray-selected and radio-selected samples of BL Lac objects. The DXRBSis the very first sample to contain statistically significant numbers ofblazars at low luminosities, approaching what should be the lower end ofthe FSRQ luminosity function. Based on observations collected at theEuropean Southern Observatory, La Silla, Chile; Kitt Peak NationalObservatory; Cerro Tololo Inter-American Observatory; and the AustraliaTelescope National Facility.
| The Parkes Half-Jansky Flat-Spectrum Sample
We present a new sample of Parkes half-jansky flat-spectrum radiosources, having made a particular effort to find any previouslyunidentified sources. The sample contains 323 sources selected accordingto a flux limit of 0.5Jy at 2.7GHz, a spectral index measured between2.7 and 5.0GHz of alpha_2.7/5.0>-0.5, where S(nu)~nu ^alpha, Galacticlatitude |b|>20 deg and -45 deg< declination (B1950) <+10 deg.The sample was selected from a region 3.90 steradians in area. We haveobtained accurate radio positions for all the unresolved sources in thissample, and combined these with accurate optical positions fromdigitized photographic sky survey data to check all the opticalidentifications. We report new identifications based on R- and Kn-bandimaging and new spectroscopic measurements of many of the sources. Wepresent a catalogue of the 323 sources, of which 321 now have identifiedoptical counterparts and 277 have measured spectral redshifts.
| 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.
| A comparative study of morphological classifications of APM galaxies
We investigate the consistency of visual morphological classificationsof galaxies by comparing classifications for 831 galaxies from sixindependent observers. The galaxies were classified on laser print copyimages or on computer screen using scans made with the Automated PlateMeasuring (APM) machine. Classifications are compared using the RevisedHubble numerical type index T. We find that individual observers agreewith one another with rms combined dispersions of between 1.3 and 2.3type units, typically about 1.8 units. The dispersions tend to decreaseslightly with increasing angular diameter and, in some cases, withincreasing axial ratio (b/a). The agreement between independentobservers is reasonably good but the scatter is non-negligible. In spiteof the scatter, the Revised Hubble T system can be used to train anautomated galaxy classifier, e.g. an artificial neural network, tohandle the large number of galaxy images that are being compiled in theAPM and other surveys.
| 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.
| Discovery of Neutral Hydrogen Associated with the Diffuse Shells of NGC 5128 (Centaurus A)
In this Letter, we present for the first time images and kinematics ofneutral hydrogen, which is unambiguously associated with the opticalshells of an E/S0 galaxy, NGC 5128. Using the VLA, we have mappeddiffuse H I (21 cm) emission out to ~15 kpc (15') from the nucleus ofthe galaxy to a limiting column density of 10^20^ cm^-2^ Theseobservations reveal the presence of 1.5 x 10^8^ M_sun_ of H I, 10'-15'NE, N, and SW of the galaxy. The H I distribution follows the curvatureof the outermost "diffuse" shells, and is slightly displaced, shifted 1'to the outside of the shells. The H I shows a smooth gradient invelocity over ~450 km s^-1^, nearly the same line-of-sight velocityrange observed in the dust lane. Our results suggest that the H I mightbe a partial ring, rotating with the same sense as the main body of thegalaxy. We discuss merger, accretion, and internal shell formationmodels and describe how the observed properties of the H I challengeexisting theories of shell formation. We also find a morphological andkinematical connection between the NE cloud of H I and the outer opticalfilaments of Cen A, identifying the H I as the source of gas beingionized. Finally, we discuss the implications of these results on thestudy of high-z radio galaxies with extended emission-line regions.
| A Survey of 526 Soutern Flat Spectrum Radio Sources with the Parkes / Tidbinbilla Interferometer
Not Available
| The Radio Nucleus of NGC4151 at 5-GHZ and 8-GHZ
We present 5- and 8-GHz observations of the Seyfert nucleus of NGC 4151.The observations have angular resolutions raging from 400 to 50 mas andsensitivities as high as 7 microJy beam^-1^. We confirm the picture of atwo-sided radio jet along PA 77^deg^, and also detect a weak component 6arcsec (400 pc) to the east which shows that collimated ejectaassociated with the jet extend at least twice as far as revealed byearlier measurements. The central knots in the jet have significantlyhigher pressure than components in the outer parts. Most of thecomponents in the source have steep spectra, although that of theeastern component in the central double is relatively flat (α = -0.3), consistent with it being associated with the optical continuumnucleus. The high- resolution MERLIN 5-GHz image of this component hasrevealed a small (150 mas) jet, which is further evidence that thiscomponent is the nucleus. We have also discovered extended weak,steep-spectrum, low-brightness emission with an `S'-shaped symmetry, andsuggest the structure to be a consequence of relativistic particles fromthe jet drifting along density gradients away from the galactic plane.The high sensitivity of the 8-GHz VLA measurements allows us to set anupper limit of 10^5^ pc cm^-6^ on the emission measure of thermal gasoutside the radio source. There is, however, possible thermal emissionstraddling the optical nucleus, which we tentatively identify withnarrow line region (NLR) gas. We discuss the geometry of the nucleus andconsider models to account for the misalignment between the NLR andextended narrow-line region (ENLR) gas and the radio jet. We favour amodel in which the misalignment is caused by density bounding of the UVcone, which implies that the collimation axis of the nucleus is at anangle of 25^deg^ to the rotation axis of NGC 4151 and 40^deg^ to theline of sight. We discuss difficulties of fitting NGC 4151 into unifiedschemes in which Seyfert 1 and 2 nuclei differ only in orientation.
| The extended 12 micron galaxy sample
We have selected an all-sky (absolute value of b greater than or equalto 25 deg) 12 micron flux-limited sample of 893 galaxies from the IRASFaint Source Catalog, Version 2 (FSC-2). We have obtained accurate totalfluxes in the IRAS wavebands by using the ADDSCAN procedure for allobjects with FSC-2 12 micron fluxes greater than 0.15 Jy and increasingflux densities from 12 to 60 microns, and defined the sample by imposinga survey limit of 0.22 Jy on the total 12 micron flux. Its completenessis verified, by means of the classical log N - log S andV/Vmax tests, down to 0.30 Jy, below which we have measuredthe incompleteness down to the survey limit, using the log N - log Splot, for our statistical analysis. We have obtained redshifts (mostlyfrom catalogs) for virtually all (98.4%) the galaxies in the sample.Using existing catalogs of active galaxies, we defined a subsample of118 objects consisting of 53 Seyfert 1s and quasars, 63 Seyfert 2s, andtwo blazars (approximately 13% of the full sample), which is the largestunbiased sample of Seyfert galaxies ever assembled. Since the 12 micronflux has been shown to be about one-fifth of the bolometric flux forSeyfert galaxies and quasars, the subsample of Seyferts (includingquasars and blazars) is complete not only to 0.30 Jy at 12 microns butalso with respect to a bolometric flux limit of approximately 2.0 x10-10 ergs/s/sq cm. The average value of V/Vmaxfor the full sample, corrected for incompleteness at low fluxes, is 0.51+/- 0.04, expected for a complete sample of uniformly distributedgalaxies, while the value for the Seyfert galaxy subsample is 0.46 +/-0.10. We have derived 12 microns and far-infrared luminosity functionsfor the AGNs, as well as for the entire sample. We extracted from oursample a complete subsample of 235 galaxies flux-limited (8.3 Jy) at 60microns. The 60 micron luminosity function computed for this subsampleis in satisfactory agreement with the ones derived from the brightgalaxy sample (BGS) and the deep high-galactic latitude sample, bothselected at 60 microns.
| Redshift observations in the Hydra-Centaurus region
The paper reports 406 redshifts for galaxies in the northern galactichemisphere, south of delta = 0 deg. A substantial fraction of theobserved galaxies are located in the equatorial zone between deltavalues of -17.5 and 0 deg. By combining these new data with thoseavailable in the literature, it is possible to extend the original CfAredshift survey of galaxies brighter than m(B(0)) = 14.5 to b = 30 deg,south of delta = 0. New data taken at lower galactic latitudes alsocontribute to the existing surveys of the Hydra-Centaurus complex.
| Flux densities at 8400 MHz for a large sample of radio sources
This paper presents 8400-MHz flux densities for 1194 southern radiosources. The sources were selected from the Parkes 2700-MHz Survey toinclude all those stronger than 0.5 Jy at that survey's findingfrequency of 2700 MHz. The new fluxes have an accuracy of about 8percent, corresponding to 0.05 Jy for a typical source. It isanticipated that the data will be useful in defining the high-frequencyradio spectra of many sources as well as in pinpointing objects withwhich to improve the southern, astrometric absolute reference frame.
| The HEAO A-1 all-sky survey of fast X-ray transients
Ten fast X-ray transient sources were discovered in the first completepass of the sky by the HEAO A-1 Sky Survey Experiment, including 7relatively faint sources and 3 bright ones. The survey technique andeach of the transients are described. Four of the transients areidentified with active coronal sources; the remaining ones areunidentified. The statistical properties of the total sample of 10sources are discussed, including event rates, distribution on the sky,and the number-flux distribution.
| VLBI observations of 416 extragalactic radio sources
Very long baseline interferometry (VLBI) observations of 416 radiosources with declinations north of -45 deg have been conducted atfrequencies of 2.3 and 8.4 GHz. At 2.3 GHz, 323 of 391 radio sourcesobserved were detected with a fringe spacing of 3 milliarcsec and adetection limit of about 0.1 Jy. At 8.4 GHz, 278 of 416 radio sourceswere detected with a fringe spacing of 1 milliarcsec and a detectionlimit of about 0.1 Jy. This survey was conducted primarily to determinethe strength of compact components at 8.4 GHz for radio sourcespreviously detected with VLBI at 2.3 GHz. Compact extragalactic radiosources with strong correlated flux densities at both frequencies areused to form a high-accuracy reference frame.
| A VLBI survey at 2.29 GHz
VLBI observations at 2.29 GHz with fringe spacings of about 3milliarcsec have been performed on 1398 radio sources spread over theentire sky. 917 sources were detected, including 93 percent of theidentified BL Lacertae objects, 86 percent of the quasars, and 36percent of the galaxies. The resulting catalog of compact radio sourcesis useful for various astrophysical studies and in the formation of VLBIcelestial reference frames.
| Very Long Baseline Interferometry observations of 257 extragalactic radio sources in the ecliptic region
Very Long Baseline Interferometry observations of 257 extragalacticradio sources with 10 deg of the ecliptic have been conducted at afrequency of 2.29 GHz. Compact components with flux densities greaterthan 0.1 Jy and angular sizes smaller than the fringe spacings of 2.5and 3.2 milliarsec were detected in 144 radio sources. This survey wasconducted to find compact radio sources to form a high accuracyreference frame for planetary spacecraft navigation. This stablereference frame may also be useful for long-term studies of planetarydynamics.
| The Ohio Survey between 0 and -36 degrees .
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1970AJ.....75..351E&db_key=AST
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