- ID:
- ivo://CDS.VizieR/J/AJ/109/853
- Title:
- VLA survey of Abell clusters. IV.
- Short Name:
- J/AJ/109/853
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the fourth in a series of papers describing an in depth study of a large statistical sample of radio galaxies in Abell clusters. This sample forms the basis of a detailed optical and radio study of the host galaxy properties, environments, and evolutionary models for radio galaxies as a class of objects. In this paper, we examine the radio detection statistics as a function of cluster morphological type, galaxy richness, and spatial location within the cluster galaxy distribution. These relationships are also parametrized as a function of radio power. The spatial distributions of the radio sources as a function of distance from the cluster center indicate that radio galaxies are preferentially located at small radii from the center of the cluster potential. This is observed as a factor of 2-3 excess over that predicted by a King-model surface-density distribution. The excess is higher in the upper radio power bin. This result is easily explained, however, from the spatial distribution of the brightest galaxies and the relationship between radio and optical luminosity. The sample is divided into richness classes 0, 1, and 2, according to Abell's criterion, and in two radio power ranges. While simple counting shows that richer clusters have more radio galaxies in both radio power bins, when the detections are scaled to the number of galaxies surveyed in each cluster, no significant correlations are found. This result implies that the number of radio galaxies detected simply scales with the number of galaxies surveyed. The higher galaxy density (and presumably higher ICM gas density) in richer clusters does not appear to affect the rate of radio source formation. The clusters are divided into Rood-Sastry and Bautz-Morgan morphological types. While it would appear that the more regular clusters have higher radio detection rates, when the classes are normalized to the number of galaxies, the radio detection rates are found to be identical regardless of cluster morphology. In conclusion, it is the optical properties of the host galaxy which most influence both the radio detection rate and the radio source properties. The cluster properties, galaxy density, and spatial location of the galaxy do not significantly affect the observed radio statistics.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/98/64
- Title:
- VLA survey of Abell clusters of galaxies I.
- Short Name:
- J/AJ/98/64
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of a VLA survey at 20cm of a complete sample of nearby Abell clusters (D<=3). We have compiled an extensive catalog of cluster radio sources with S_20_>10mJy from a combination of our VLA observations and observations of similar resolution with the Westerbork Synthesis Radio Telescope (WSRT). Using these radio data and X-ray data from the Einstein observatory, we have analyzed the properties of these clusters. Unlike that previously suggested, no significant correlation is found between 20cm radio power and X-ray luminosity. There is weak evidence that richer clusters have a higher probability of radio emission. Based on Rood-Sastry morphological types of clusters, we do not find any strong evidence that regular-type clusters are statistically more likely to be radio loud than irregular-type clusters. However, Bautz-Morgan types I and II-III are found to have comparable radio-detection rates; but Bautz-Morgan Type III clusters are likely to have a lower radio-detection rate. A weak correlation between X-ray-cooling mass-accretion rates and radio powers was found for central, dominant galaxies in cooling-flow clusters. This might suggest that either cooling accretion directly fuels the central engine and/or cooling flows strongly interact with (e.g., confine) the radio plasma. In addition, radio sources associated with central dominant galaxies in cooling-flow clusters tend to be small in comparison with those in non-cooling-flow clusters. This might suggest that cooling flows tend to obstruct the propagation of radio jets from central, dominant galaxies.
1023. VLA survey of CDF-S. II.
- ID:
- ivo://CDS.VizieR/J/ApJS/179/95
- Title:
- VLA survey of CDF-S. II.
- Short Name:
- J/ApJS/179/95
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the optical and infrared identifications of the 266 radio sources detected at 20cm with the Very Large Array in the Chandra Deep Field-South. Using deep i-band Advanced Camera for Surveys, R-band Wide Field Imager, K-band SOFI NTT, K-band ISAAC VLT and Spitzer imaging data, we are able to find reliable counterparts for 254 (~95%) VLA sources. Twelve radio sources remain unidentified, and three of them are "empty fields". Using literature and our own data we are able to assign redshifts to 186 (~70%) radio sources: 108 are spectroscopic redshifts and 78 are reliable photometric redshifts. Based on the rest-frame colors and morphological distributions of the host galaxies, we find evidences for a change in the submillijansky radio source population: (1) above ~0.08mJy early-type galaxies are dominating and (2) at flux densities below ~0.08mJy, starburst galaxies become dominant.
- ID:
- ivo://CDS.VizieR/VIII/50
- Title:
- VLA Survey of Rich Clusters of Galaxies
- Short Name:
- VIII/50
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We observed 60 fields towards 57 Abell and one Zwicky cluster of galaxies using the Very Large Array (VLA) with scaled arrays at 1.5 and 4.9 GHz. The source catalogue contains radio and optical parameters for 994 sources up to a lower flux limit of 1.0 mJy at 1.5 GHz and comprises a complete sample above 2.5 mJy. The combined sky area within the half-power circle on the maps is 3.5x10^-3^ sr, and the cluster fields are distributed between +35 deg and -30 deg declination. The source catalogue list positions, angular size, spectral index and optical identification, magnitude and morphology, if available.
- ID:
- ivo://CDS.VizieR/J/ApJS/179/71
- Title:
- VLA survey of the CDF-S I.
- Short Name:
- J/ApJS/179/71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report 20 and 6cm VLA deep observations of the CDF-S including the Extended CDF-S. We discuss the radio properties of 266 cataloged radio sources, of which 198 are above a 20cm completeness level reaching down to 43uJy at the center of the field. Survey observations made at 6cm over a more limited region cover the original CDF-S to a comparable level of sensitivity as the 20cm observations. Of 266 cataloged radio sources, 52 have X-ray counterparts in the CDF-S and a further 37 have counterparts in the E-CDF-S area not covered by the 1Ms exposure. Using a wide range of material, we have found optical or infrared counterparts for 254 radio sources, of which 186 have either spectroscopic or photometric redshifts. Three radio sources have no apparent counterpart at any other wavelength. Measurements of the 20cm radio flux density at the position of each CDF-S X-ray source detected a further 30 radio sources above a conservative 3{sigma} detection limit. X-ray and submillimeter observations have been traditionally used as a measure of AGN and star formation activity, respectively. These new observations probe the faint end of both the star formation and radio galaxy/AGN population, as well as the connection between the formation and evolution of stars and SMBHs.
1026. VLA-VIRMOS Deep Field
- ID:
- ivo://CDS.VizieR/J/A+A/403/857
- Title:
- VLA-VIRMOS Deep Field
- Short Name:
- J/A+A/403/857
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have conducted a deep survey (rms noise ~=17{mu}Jy) with the Very Large Array (VLA) at 1.4GHz, with a resolution of 6arcsec, of a 1{deg}^2^ region included in the VIRMOS VLT Deep Survey. In the same field we already have multiband photometry down to I_AB_=25, and spectroscopic observations will be obtained during the VIRMOS VLT survey. The homogeneous sensitivity over the whole field has allowed to derive a complete sample of 1054 radio sources (5{sigma} limit). We give a detailed description of the data reduction and of the analysis of the radio observations, with particular care to the effects of clean bias and bandwidth smearing, and of the methods used to obtain the catalogue of radio sources. To estimate the effect of the resolution bias on our observations we have modelled the effective angular-size distribution of the sources in our sample and we have used this distribution to simulate a sample of radio sources. Finally we present the radio count distribution down to 0.08mJy derived from the catalogue. Our counts are in good agreement with the best fit derived from earlier surveys, and are about 50% higher than the counts in the HDF. The radio count distribution clearly shows, with extremely good statistics, the change in the slope for the sub-mJy radio sources.
- ID:
- ivo://CDS.VizieR/J/ApJ/861/113
- Title:
- VLBA astrometry combined with Gaia DR1 epoch
- Short Name:
- J/ApJ/861/113
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The canonical methods for gravitational wave detection are ground- and space- based laser interferometry, pulsar timing, and polarization of the cosmic microwave background. But as has been suggested by numerous investigators, astrometry offers an additional path to gravitational wave detection. Gravitational waves deflect light rays of extragalactic objects, creating apparent proper motions in a quadrupolar (and higher-order modes) pattern. Astrometry of extragalactic radio sources is sensitive to gravitational waves with frequencies between roughly 10^-18^ and 10^-8^Hz (H_0_ and 1/3yr^-1^), overlapping and bridging the pulsar timing and CMB polarization regimes. We present a methodology for astrometric gravitational wave detection in the presence of large intrinsic uncorrelated proper motions (i.e., radio jets). We obtain 95% confidence limits on the stochastic gravitational wave background using 711 radio sources, {Omega}_GW_<0.0064, and using 508 radio sources combined with the first Gaia data release: {Omega}_GW_<0.011. These limits probe gravitational wave frequencies 6x10^-18^Hz<~f<~1x10^-9^Hz. Using a WISE-Gaia catalog of 567721 AGN, we predict a limit expected from Gaia alone of {Omega}_GW_<0.0006, which is significantly higher than was originally forecast. Incidentally, we detect and report on 22 new examples of optical superluminal motion with redshifts 0.13-3.89.
- ID:
- ivo://CDS.VizieR/J/ApJS/141/13
- Title:
- VLBA calibrator survey: VCS1 catalog
- Short Name:
- J/ApJS/141/13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A catalog containing milli-arcsecond-accurate positions of 1332 extragalactic radio sources distributed over the northern sky is presented - the Very Long Baseline Array Calibrator Survey (VCS1). The positions have been derived from astrometric analysis of dual-frequency 2.3 and 8.4 GHz VLBA snapshot observations; in a majority of cases, images of the sources are also available. These radio sources are suitable for use in geodetic and astrometric experiments, and as phase-reference calibrators in high-sensitivity astronomical imaging. The VCS1 is the largest high-resolution radio survey ever undertaken and triples the number of sources available to the radio astronomy community for VLBI applications. In addition to the astrometric role, this survey can be used in active galactic nuclei, Galactic, gravitational lens, and cosmological studies.
- ID:
- ivo://CDS.VizieR/J/A+A/450/959
- Title:
- VLBA images of High Frequency Peakers
- Short Name:
- J/A+A/450/959
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We propose a morphological classification based on the parsec scale structure of fifty-one High Frequency Peakers (HFPs) from the "bright" HFP sample. VLBA images at two adjacent frequencies (chosen among 8.4, 15.3, 22.2 and 43.2GHz) have been used to investigate the morphological properties of the HFPs in the optically thin part of their spectrum. We confirm that there is quite a clear distinction between the pc-scale radio structure of galaxies and quasars: the 78% of the galaxies show a "Double/Triple" morphology, typical of Compact Symmetric Objects (CSOs), while the 87% of the quasars are characterised by Core-Jet or unresolved structure. This suggests that most HFP candidates identified with quasars are likely blazar objects in which a flaring self-absorbed component at the jet base was outshining the remainder of the source at the time of the selection based on the spectral shape. Among the sources classified as CSOs or candidates it is possible to find extremely young radio sources with ages of about 100 years or even less.
- ID:
- ivo://CDS.VizieR/J/ApJ/658/203
- Title:
- VLBA imaging and polarimetry survey at 5GHz
- Short Name:
- J/ApJ/658/203
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first results of the VLBA Imaging and Polarimetry Survey (VIPS), a 5GHz VLBI survey of 1119 sources with flat radio spectra. Through automated data reduction and imaging routines, we have produced publicly available I, Q, and U images and have detected polarized flux density from 37% of the sources. We have also developed an algorithm to use each source's I image to automatically classify it as a pointlike source, a core jet, a compact symmetric object (CSO) candidate, or a complex source. Using data from the Sloan Digital Sky Survey (SDSS), we have found no significant trend between optical flux and 5 GHz flux density for any of the source categories.
