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17091. VLA Survey of Rich Clusters of Galaxies
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.
17092. VLA survey of the CDF-S I.
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.
17093. VLA SWIRE Deep Field 90-cm Source Catalog
ID:
ivo://nasa.heasarc/vlasdf90cm
Title:
VLA SWIRE Deep Field 90-cm Source Catalog
Short Name:
VLASDF90CM
Date:
01 Nov 2024
Publisher:
NASA/GSFC HEASARC
Description:
This table contains some of the results from the deepest radio continuum surveys to date at a radio wavelength of >~ 1m. The observations were taken with the VLA at 324.5 MHz covering a region of the SWIRE Spitzer Legacy survey, centered at RA and Dec of 10:46:00, +59:01:00 (J2000). The data reduction and analysis are described in the reference paper and a catalog of the sources detected above 5 sigma is presented herein. The authors also discuss the observed angular size distribution for the sample in their paper, and, using their deeper 20-cm survey of the same field (Owen and Morrison 2008, AJ, 136, 1889), they calculate spectral indices for sources detected in both surveys. They report log N-log S counts at 90 cm which show a flattening below 5 mJy. Given the median redshift of the population, z ~ 1, the spectral flattening and the flattening of the log N-log S counts occur at radio luminosities normally associated with AGN rather than with galaxies dominated by star formation. Observations were made of a single pointing center position (given above), with the VLA in A and C configurations for a total of almost 85 hours on-source between 2006 February and 2007 January. However, due to the ongoing EVLA upgrade, only 22 working antennae were typically avaliable in A and 18 in C. Thus, the total integration time was equivalent to ~ 63 hours in A and even less in C, with correspondingly less u-v coverage. This table was created by the HEASARC in September 2010 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/AJ/137/4846/">CDS catalog J/AJ/137/4846/</a> file table2.dat. This is a service provided by NASA HEASARC .
17094. VLA SWIRE Deep Field 20-cm Source Catalog
ID:
ivo://nasa.heasarc/vlasdf20cm
Title:
VLA SWIRE Deep Field 20-cm Source Catalog
Short Name:
VLASDF20CM
Date:
01 Nov 2024
Publisher:
NASA/GSFC HEASARC
Description:
This table contains some of the results from deep radio observations taken with the Very Large Array at a center frequency of 1400 MHz covering a region of the Spitzer Wide-area InfraRed Extragalactic (SWIRE) Survey of the Spitzer Legacy survey, centered at RA and Dec of 10:46:00, +59:01:00 (J2000). The reduction and cataloging of radio sources are described in the reference paper. This table comprises the catalog of the sources detected above 5 sigma. The survey presented is the deepest so far in terms of the radio source density on the sky. Perhaps surprisingly, the sources down to the bottom of the catalog appear to have median angular sizes which are still greater than 1 arcsecond, like their cousins 10-100 times stronger. The shape of the differential log N-log S counts also seems to require a correction for the finite sizes of the sources in order to be self-consistent. If the log N-log S normalization remains constant at the lowest flux densities, there are about six sources per square arcminute at 15 µJy (µJy) at 20 cm. Given the finite-source size this implies that we may reach the natural confusion limit near 1 uJy. The observations were made with the VLA in A, B, C, and D configurations for a total of almost 140 hr on-source between 2001 December and 2004 January. Since the total time is dominated by the A congiguration, the final image for analysis has a resolution of ~1.6 arcseconds. This table was created by the HEASARC in September 2010 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/AJ/136/1889/">CDS catalog J/AJ/136/1889/</a> file table2.dat. This is a service provided by NASA HEASARC .
17095. 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.
17096. VLA-VIRMOS Deep Field 20-cm Source Catalog
ID:
ivo://nasa.heasarc/vvds20cm
Title:
VLA-VIRMOS Deep Field 20-cm Source Catalog
Short Name:
VVDS20CM
Date:
01 Nov 2024
Publisher:
NASA/GSFC HEASARC
Description:
The authors of this table conducted a deep survey (rms noise ~ 17 microJansky or uJy) with the Very Large Array (VLA) at 1.4 GHz, with a resolution of 6 arcseconds, of a 1 deg<sup>2</sup> region included in the VIRMOS VLT Deep Survey that is centered at RA and Dec (J2000.0) of 02 26 00, -04 30 00, hereafter the VLA-VIRMOS Deep Field, or VLA-VDF. In the same field, they already had multiband photometry down to I<sub>AB</sub> = 25, and spectroscopic observations were to be obtained during the VIRMOS VLT survey. The homogeneous sensitivity over the whole field allowed them to derive a complete sample of 1054 radio sources (5-sigma limit) down to a limit of 0.08 mJy. In their paper, the authors 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 catalog of radio sources. To estimate the effect of the resolution bias on their observations, they have modeled the effective angular-size distribution of the sources in their sample and they have used this distribution to simulate a sample of radio sources. Finally, they present the radio count distribution down to 0.08 mJy derived from the catalog. Their counts are in good agreement with the best fit derived from earlier surveys, and are about 50% higher than the counts in the Hubble Deep Field (HDF). The radio count distribution clearly shows, with extremely good statistics, the change in the slope for the sub-mJy radio sources. 19 of the 1054 radio sources were fitted with multiple components. In such cases, the authors list in the catalog an entry for each of the components, identified with a trailing letter (A, B, C or D) in the source name, and an entry for the whole source, identified with a trailing T in the source name. In these cases the total flux was calculated using the task TVSTAT, which allows the integration of the map values over irregular areas, and the sizes are the largest angular sizes. Thus, this catalog contains 1103 entries on 1054 sources, including 49 entries on individual components of composite sources. This table was created by the HEASARC in February 2012 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/403/857">CDS Catalog J/A+A/403/857</a> file catalog.dat. This is a service provided by NASA HEASARC .
17097. VLA/VLBA obscured radio-loud active galactic nuclei
ID:
ivo://CDS.VizieR/J/AJ/151/74
Title:
VLA/VLBA obscured radio-loud active galactic nuclei
Short Name:
J/AJ/151/74
Date:
21 Oct 2021
Publisher:
CDS
Description:
This is the second paper directed toward finding new highly redshifted atomic and molecular absorption lines at radio frequencies. To this end, we selected a sample of 80 candidates for obscured radio-loud active galactic nuclei (AGNs) and presented their basic optical/near-infrared (NIR) properties in Yan et al. 2012AJ....144..124Y. In this paper, we present both high-resolution radio continuum images for all of these sources and H I 21 cm absorption spectroscopy for a few selected sources in this sample. A-configuration 4.9 and 8.5 GHz Very Large Array continuum observations find that 52 sources are compact or have substantial compact components with size <0.5" and flux densities >0.1 Jy at 4.9 GHz. The 36 most compact sources were then observed with the Very Long Baseline Array at 1.4 GHz. One definite and 10 candidate Compact Symmetric Objects (CSOs) are newly identified, which is a detection rate of CSOs ~three times higher than the detection rate previously found in purely flux-limited samples. Based on possessing compact components with high flux densities, 60 of these sources are good candidates for absorption-line searches. Twenty-seven sources were observed for H I 21 cm absorption at their photometric or spectroscopic redshifts with only six detections (five definite and one tentative). However, five of these were from a small subset of six CSOs with pure galaxy optical/NIR spectra (i.e., any AGN emission is obscured) and for which accurate spectroscopic redshifts place the redshifted 21 cm line in a radio frequency intereference (RFI)-free spectral "window" (i.e., the percentage of H I 21 cm absorption-line detections could be as high as ~90% in this sample). It is likely that the presence of ubiquitous RFI and the absence of accurate spectroscopic redshifts preclude H I detections in similar sources (only 1 detection out of the remaining 22 sources observed, 13 of which have only photometric redshifts); that is, H I absorption may well be present but is masked by the RFI. Future searches for highly redshifted H I and molecular absorption can easily find more distant CSOs among bright, "blank field" radio sources, but will be severely hampered by an inability to determine accurate spectroscopic redshifts due to their lack of rest-frame UV continuum.
17098. VLA XMM Large Scale Structure Field 325-MHz Source Catalog
ID:
ivo://nasa.heasarc/vlaxl325mh
Title:
VLA XMM Large Scale Structure Field 325-MHz Source Catalog
Short Name:
VLAXL325MH
Date:
01 Nov 2024
Publisher:
NASA/GSFC HEASARC
Description:
The XMM Large Scale Structure survey (XMM-LSS) is an X-ray survey aimed at studying the large scale structure of the Universe. The XMM-LSS field (centered at RA (J2000) = 02&lt;sup&gt;h&lt;/sup&gt; 24&lt;sup&gt;m&lt;/sup&gt; 00.27&lt;sup&gt;s&lt;/sup&gt;, Dec (J2000) = -04&lt;sup&gt;o&lt;/sup&gt; 09&#39; 47.6&quot;) is currently being followed up using observations across a wide range of wavelengths, and in their paper the authors present the observational results of a low frequency radio survey of the XMM-LSS field using the Very Large Array at 74 and 325 MHz. This survey will map out the locations of the extragalactic radio sources relative to the large scale structure as traced by the X-ray emission. This is of particular interest because radio galaxies and radio-loud AGN show strong and complex interactions with their small and larger scale environment, and different classes of radio galaxies are suggested to lie at different places with respect to the large scale structure. For the phase calibration of the radio data, the authors used standard self-calibration at 325 MHz and field-base calibration at 74 MHz. Polyhedron-based imaging as well as mosaicking methods were used at both frequencies. At 74 MHz, the resolution was 30 arcseconds, the median 5-sigma sensitivity was ~ 162 mJy/beam and 666 sources were detected over an area of 132 square degrees. At 325 MHz, the resolution was 6.7 arcseconds, the median 5-sigma sensitivity was 4 mJy/beam, and 847 sources were detected over an area of 15.3 square degrees. At 325 MHz, a region of diffuse radio emission which is a cluster halo or relic candidate was detected. The observations were conducted using the VLA in July 2003 in the A-configuration (most extended) and in June 2002 in the B-configuration. This table contains the VLA 325-MHz source list, comprising 605 single sources and 615 components of 237 multiple sources, for a total of 1220 entries. (Notice that, in Section 4.1 of the reference paper, somewhat different numbers are given, i.e., the authors quote 621 single sources and 226 multiple sources). For the multiple sources, each component (A, B, etc.) is listed separately, in order of decreasing brightness. This table was created by the HEASARC in March 2012 based on &lt;a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/456/791"&gt;CDS Catalog J/A+A/456/791&lt;/a&gt; file tablea1.dat. This is a service provided by NASA HEASARC .
17099. VLA XMM Large Scale Structure Field 74-MHz Source Catalog
ID:
ivo://nasa.heasarc/vlaxl74mhz
Title:
VLA XMM Large Scale Structure Field 74-MHz Source Catalog
Short Name:
VLAXL74MHZ
Date:
01 Nov 2024
Publisher:
NASA/GSFC HEASARC
Description:
The XMM Large Scale Structure survey (XMM-LSS) is an X-ray survey aimed at studying the large scale structure of the Universe. The XMM-LSS field (centered at RA (J2000) = 02&lt;sup&gt;h&lt;/sup&gt; 24&lt;sup&gt;m&lt;/sup&gt; 00.27&lt;sup&gt;s&lt;/sup&gt;, Dec (J2000) = -04&lt;sup&gt;o&lt;/sup&gt; 09&#39; 47.6&quot;) is currently being followed up using observations across a wide range of wavelengths, and in their paper the authors present the observational results of a low frequency radio survey of the XMM-LSS field using the Very Large Array at 74 and 325 MHz. This survey will map out the locations of the extragalactic radio sources relative to the large scale structure as traced by the X-ray emission. This is of particular interest because radio galaxies and radio-loud AGN show strong and complex interactions with their small and larger scale environment, and different classes of radio galaxies are suggested to lie at different places with respect to the large scale structure. For the phase calibration of the radio data, the authors used standard self-calibration at 325 MHz and field-base calibration at 74 MHz. Polyhedron-based imaging as well as mosaicking methods were used at both frequencies. At 74 MHz, the resolution was 30 arcseconds, the median 5-sigma sensitivity was ~ 162 mJy/beam and 666 sources were detected over an area of 132 square degrees. At 325 MHz, the resolution was 6.7 arcseconds, the median 5-sigma sensitivity was 4 mJy/beam, and 847 sources were detected over an area of 15.3 square degrees. At 325 MHz, a region of diffuse radio emission which is a cluster halo or relic candidate was detected. The observations were conducted using the VLA in July 2003 in the A-configuration (most extended) and in June 2002 in the B-configuration. This table contains the VLA 74-MHz source list, comprising 617 single sources and 108 components of 51 multiple sources, for a total of 725 entries. (Notice that, in Section 4.3 of the reference paper, somewhat different numbers are given, i.e., the authors quote 615 single sources). For the multiple sources, each component (A, B, etc.) is listed separately, in order of decreasing brightness. This table was created by the HEASARC in March 2012 based on &lt;a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/456/791"&gt;CDS Catalog J/A+A/456/791&lt;/a&gt; file tablea2.dat. This is a service provided by NASA HEASARC .
17100. VLBA astrometry combined with Gaia DR1 epoch
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.

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