- ID:
- ivo://CDS.VizieR/J/MNRAS/344/283
- Title:
- 100-Mpc-scale structures of radio galaxies
- Short Name:
- J/MNRAS/344/283
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present unequivocal evidence for a huge (~80x100x100Mp^3^) superstructure at redshift z=0.27 in the three-dimensional distribution of radio galaxies from the Texas-Oxford NVSS Structure 08h region (TONS08) sample, confirming tentative evidence for such a structure from the 7C redshift survey (7CRS). A second, newly discovered superstructure is also found less securely at redshift 0.35 (of dimensions ~100x100x100Mpc^3^). We present full observational details on the TONS08 sample which was constructed to probe structures in the redshift range 0<z<0.5 by matching NVSS sources with objects in APM catalogues to obtain a sample of optically bright (E~R<=19.83), radio-faint (1.4GHz flux density S_1.4_>=3mJy) radio galaxies in the same 25deg^2^ area as part II of the 7CRS.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJS/107/19
- Title:
- MRC/1Jy Radio source survey. I.
- Short Name:
- J/ApJS/107/19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the first in a series of papers discussing the properties of a complete set of radio sources selected near S408=1Jy. We present optical or infrared identifications for a sample of 452 radio galaxies. The sources were selected from the 408MHz Molonglo Reference Catalog, restricted only by flux density and position on the sky, as follows: S408>0.95Jy and -30<decl.(1950)<-20, and 9h20m<R.A.(1950)<14h4m or 20h20m<R.A.(1950)<6h14m. This complete sample, the MRC/1 Jy survey, contains 558 radio galaxies or quasars, of which six are occulted by bright stars or galaxies and two are multiple confused sources. Of the remaining 550 sources, 527, or 96%, are identified to an r magnitude of 25, and eight additional sources are identified to K=19. Of the 17 unocculted objects that remain unidentified, 15 are sources for which we have either poor radio maps or inadequate optical/IR images. This paper presents finding charts and astrometric positions for the 452 sources that are not identified as either quasars or BL Lacertae objects. Magnitudes in the r passband accurate to typically 0.1mag are given for 353 of the radio galaxy identifications. Redshifts for 268 of the galaxies are also listed; these have been derived from 450 spectroscopic observations. The radio observations, quasar and BL Lac identifications, spectroscopy, and near-IR images will be presented in subsequent papers in this series.
- ID:
- ivo://CDS.VizieR/J/MNRAS/381/341
- Title:
- MRCR-SUMSS Ultra-steep-spectrum (USS) sample
- Short Name:
- J/MNRAS/381/341
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper introduces a new program to find high-redshift radio galaxies in the Southern hemisphere through ultra-steep spectrum (USS) selection. We define a sample of 234 USS radio sources with spectral indices {alpha}^843^_408_<=-1.0 (S_{nu}_{prop.to}{nu}^alpha^) and flux densities S_408_>=200mJy in a region of 0.35sr, chosen by cross-correlating the revised 408MHz Molonglo Reference Catalogue, the 843MHz Sydney University Molonglo Sky Survey and the 1400MHz NRAO VLA Sky Survey in the overlap region -40{deg}<DE<-30{deg}. We present Australia Telescope Compact Array (ATCA) high-resolution 1384 and 2368MHz radio data for each source, which we use to analyse the morphological, spectral index and polarization properties of our sample. We find that 85 per cent of the sources have observed-frame spectral energy distributions that are straight over the frequency range 408-2368MHz, and that, on average, sources with smaller angular sizes have slightly steeper spectral indices and lower fractional linear polarization. Fractional polarization is anticorrelated with flux density at both 1400 and 2368MHz. We also use the ATCA data to determine observed-frame Faraday rotation measures for half of the sample.
- ID:
- ivo://CDS.VizieR/J/MNRAS/432/1178
- Title:
- 2MTF. HI observations of 303 southern galaxies
- Short Name:
- J/MNRAS/432/1178
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new 21-cm neutral hydrogen (HI) observations of spiral galaxies for the 2MASS Tully-Fisher (2MTF) survey. Using the 64-m Parkes radio telescope multibeam system we obtain 152 high signal to noise ratio HI spectra from which we extract 148 high-accuracy (<5% error) velocity widths and derive reliable rotation velocities. The observed sample consists of 303 southern ({delta}<-40{deg}) galaxies selected from the 2MASS Redshift Survey with Ks<11.25mag, cz<10000km/s and axis ratio b/a<0.5. The HI observations reported in this paper will be combined with new HI spectra from the Green Bank and Arecibo telescopes, together producing the most uniform Tully-Fisher survey ever constructed (in terms of sky coverage). In particular, due to its near-infrared selection, 2MTF will be significantly more complete at low Galactic latitude (|b|<15{deg}) and will provide a more reliable map of peculiar velocities in the local Universe.
- ID:
- ivo://CDS.VizieR/J/A+A/484/119
- Title:
- Multi-epoch VLBI survey of CJF sources
- Short Name:
- J/A+A/484/119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the second in a series of papers presenting VLBI observations of the 293 Caltech-Jodrell Bank Flat-spectrum (hereafter CJF) sources and their analysis. We obtain a consistent motion dataset large enough to allow the systematic properties of the population to be studied. We present detailed kinematic analysis of the complete flux-density limited CJF survey. We computed 2-D kinematic models based on the optimal model-fitting parameters of multi-epoch VLBA observations. This allows us to calculate not only radial, but also orthogonal motions, and thus to study curvature and acceleration. Statistical tests of the motions measured and their reliability were performed. A correlation analysis between the derived apparent motions, luminosities, spectral indices, and core dominance and the resulting consequences is described. With at least one velocity in each of the 237 sources, this sample is much larger than any available before, so it allows a meaning ful statistical investigation of apparent motions and any possible correlations with other parameters in AGN jets. The main results to emerge are as follows: * In general motions are not consistent with a single uniform velocity applicable to all components along a jet. * We find a slight trend towards a positive outward acceleration and also adduce some evidence for greater acceleration in the innermost regions. * We find a lack of fast components at physical distances less than a few pc from the reference feature. * Only ~4% of the components from galaxies and <2% of those from quasars undergo large bends i.e. within 15{deg} of +/-90{deg}. * The distribution of radial velocities shows a broad distribution of velocities (apparent velocities up to 30c). Fifteen percent of the best-sampled jet components exhibit low velocities that may need to be explained in a different manner to the fast motions. * Some negative superluminal motions are seen, and in 15 cases (6%) these are definitely significant. * We find a strong correlation between the 5 GHz luminosity and the apparent velocity. * The CJF galaxies, on average, show slower apparent jet-component velocities than the quasars. * The mean velocity in the VLBA 2cm survey (Kellermann et al. 2004) is substantially higher than in the CJF survey, the ratio could be roughly a factor of 1.5-2. This supports the observed trend toward increasing apparent velocity with in creasing observing frequency. This AGN survey provides the basis for any statistical analysis of jet and jet-component properties.
- ID:
- ivo://CDS.VizieR/J/A+A/625/A102
- Title:
- MUSE datacube of MRC 0943-242
- Short Name:
- J/A+A/625/A102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used the Multi-Unit Spectroscopic Explorer (MUSE) to study the circumgalactic medium (CGM) of a z=2.92 radio galaxy, MRC 0943-242 by parametrising its emitting and absorbing gas. In both Ly{alpha} {lambda}1216 and HeII {lambda}1640 lines, we observe emission with velocity shifts of {Delta}v=~-1000km/s from the systemic redshift of the galaxy. These blueshifted components represent kinematically perturbed gas that is aligned with the radio axis, which we interpret as jet-driven outflows. Three of the four known Ly absorbers are detected at the same velocity as CIV {lambda}{lambda}1548,1551 and NV {lambda}{lambda}1239,1243 absorbers, proving that the gas is metal-enriched more so than previously thought. At the velocity of a strong Ly{alpha} absorber with an HI column of N_HI_/cm^-2^=10^19.2^ and velocity shift of Delta}v=~-400km/s, we also detect SiII {lambda}1260 and SiII {lambda}1527 absorption, which suggests that the absorbing gas is ionisation bounded. With the added sensitivity of this MUSE observation, we are more capable of adding constraints to absorber column densities and consequently determining what powers their ionisation. To do this, we obtain photoionisation grid models in cloudy which show that AGN radiation is capable of ionising the gas and producing the observed column densities in a gas of metallicity of Z/Z_{sun}_~=0.01 with a nitrogen abundance a factor of 10 greater than that of hydrogen. This metal-enriched absorbing gas, which is also spatially extended over a projected distance of r>~60kpc, is likely to have undergone chemical enrichment through stellar winds that have swept up metals from the interstellar-medium and deposited them in the outer regions of the galaxy's halo.
- ID:
- ivo://CDS.VizieR/J/A+A/581/A33
- Title:
- Nearby radio galaxies FUV to MIR properties
- Short Name:
- J/A+A/581/A33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate whether the far-UV continuum of nearby radio galaxies is due solely to the parent galaxy that passively evolves, or if it reveals evidence for the presence of other star-forming or non-stellar components. If the UV excess is due to an additional radiation component, we compare this with other properties such as radio power, optical spectral type (e.g. high- and low-excitation galaxies), and the strength of the emission lines. We also discuss the possible correlation between the ultraviolet flux, IR properties, and the central black hole mass. We used a sample of low-luminosity B2 radio galaxies and a small sample of higher luminosity 3C radio galaxies at comparable redshift (z<0.2). Spectral energy distributions (SEDs) were constructed using a number of on-line databases that are freely available now: GALEX, SDSS, 2MASS, and WISE. These were compared with model SEDs of early-type galaxies with passively evolving stellar populations at various ages (typically 0.5-1.3x10^9^ years). We established whether a second component was needed to obtain a satisfactory fit with the observed overall SED. We introduce the parameter XUV, which measures the excess slope of the UV continuum between 4500 and 2000{AA} with respect to the UV radiation produced by the underlying old galaxy component. We find that the UV excess as measured by XUV is usually small or absent in low-luminosity (FR I) sources, but sets in abruptly at the transition radio power, above which we find mostly FRII sources. XUV behaves very similarly to the strength of the optical emission lines (in particular H{alpha}). Below P_1.4GHz_<10^24^W/Hz XUV is close to zero. XUV correlates strongly with the H{alpha} line strength, but only in sources with strong H{alpha} emission. We discuss whether the line emission might be due to photoionization by radiation from the parent galaxy, possibly with additional star formation, or if it requires the presence of a non-stellar active galactic nucleus component. XUV and the slope of the mid-IR are strongly correlated, as measured by the WISE bands in the interval 3.4 to 22{mu}m, in the sense that sources with a strong UV excess also have stronger IR emission. There is an inverse correlation between XUV and central black hole mass: the M_BH_ of objects with strong UV excess is on average two to three times less massive than that of objects without UV excess. Low-luminosity radio galaxies tend to be more massive and contain more massive black holes.
- ID:
- ivo://CDS.VizieR/J/A+A/466/481
- Title:
- Near-infrared survey around PKS 1343-601
- Short Name:
- J/A+A/466/481
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The highly obscured radio-bright galaxy PKS 1343-601 at Galactic coordinates of (l,b)=(309.7,+1.8) has been suspected to mark the centre of a hitherto unknown cluster in the wider Great Attractor region. As such it presents an ideal region for a search of galaxies in the near-infrared (NIR) and an in-depth study of their colours as a function of extinction. A visual search of a ~30 square-degree area centred on this radio galaxy on images of the NIR DENIS survey (IJK) revealed 83 galaxies (including two AGNs) and 39 possible candidates. Of these, 49 are also listed in the 2MASS Extended Source Catalog 2MASX. Taking the IRAS/DIRBE extinction values (Schlegel et al., 1998ApJ...500..525S) at face value, the absorption in the optical (AB) ranges from ~2mag to over 100mag across the Galactic Plane. Comparing the detections with other systematic surveys, we conclude that this search is highly complete up to the detection limits of the DENIS survey and certainly surpasses any automatic galaxy finding algorithm applied to crowded areas.
- ID:
- ivo://CDS.VizieR/J/MNRAS/354/980
- Title:
- Near-infrared survey around PKS 1343-601
- Short Name:
- J/MNRAS/354/980
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a deep near-infrared survey of a 36x36arcmin^2^ region centred on the giant elliptical radio galaxy PKS 1343-601, suggested to be the core of an unknown rich cluster located at the low Galactic latitude of b=1.73{deg} in the Great Attractor (GA) region. 19 obvious galaxies and 38 galaxy candidates have been detected; only three of them were previously identified as a galaxy.
- ID:
- ivo://CDS.VizieR/J/A+A/446/97
- Title:
- NEP Distant Cluster Radio Galaxies
- Short Name:
- J/A+A/446/97
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A complete sample of 18 X-ray selected clusters of galaxies belonging to the ROSAT North Ecliptic Pole (NEP) survey has been observed with the Very Large Array at 1.4GHz in B configuration. These are the most distant clusters in the X-ray survey with redshift in the range 0.3<z<0.8. Seventy-nine radio sources are detected within half an Abell radius with an observed peak brightness >=0.17mJy/beam, except for three sources, belonging to the same cluster, which have a higher peak brightness limit of 0.26mJy/beam. The NEP field source counts are in good agreement with the source counts of a comparison survey, the VLA-VIRMOS deep field survey, indicating that the NEP sample is statistically complete. Thirty-two out of the 79 sources are within 0.2 Abell radii, twenty-two of them are considered cluster members based on spectroscopic redshifts or their optical magnitude and morphological classification. The cluster radio galaxies are used to construct the Radio Luminosity Function (RLF) of distant X-ray selected clusters. A comparison with two nearby cluster RLFs shows that the NEP RLF lies above the local ones, has a steeper slope at low radio powers (<=10^24^W/Hz) and shows no evidence for a break at about 6x10^24^W/Hz which is observed in the nearby cluster RLFs. We discuss briefly the origin and possible explanations of the differences observed in the radio properties of nearby and distant clusters of galaxies. The main result of this study is that the RLF of the distant X-ray clusters is very different from that of the local rich Abell clusters.
