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.
We discuss the X-ray properties of the radio sources detected in a deep 1.4 and 5GHz VLA Radio survey of the Extended Chandra Deep Field-South (E-CDFS). Among the 266 radio sources detected, we find 89 sources (1/3 of the total) with X-ray counterparts in the catalog of the 1Ms exposure of the central 0.08deg^2^ or in the catalog of the 250ks exposure of the 0.3deg^2^ E-CDFS field. For 76 (85%) of these sources, we have spectroscopic or photometric redshifts, and therefore we are able to derive their intrinsic properties from X-ray spectral analysis, namely intrinsic absorption and total X-ray luminosities. We find that the population of submillijansky radio sources with X-ray counterparts is composed of a mix of roughly 1/3 star-forming galaxies and 2/3 active galactic nuclei (AGNs).
This table contains some of the results from 20 and 6 cm VLA deep observations of the Chandra Deep Field-South (CDF-S), including the Extended CDF-S (E-CDF-S). In the reference paper, the authors discuss the radio properties of 266 cataloged radio sources, of which 198 are above a 20-cm completeness level reaching down to 43 microJanskies (µJy) at the center of the field. Survey observations made at 6 cm over a more limited region cover the original CDF-S to a comparable level of sensitivity as the 20-cm 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 1 Ms exposure. Using a wide range of material, the authors 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 20-cm radio flux density at the position of each CDF-S X-ray source detected a further 30 radio sources (not included in this table) above a conservative 3-sigma detection limit. X-ray and sub-millimeter 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. Both of the corresponding gravitational and nuclear fusion-driven energy sources can lead to radio synchrotron emission. AGN and radio galaxies dominate at high flux densities. Although emission from star formation becomes more prominent at the microJansky levels reached by deep radio surveys, even for the weakest sources, an apparent significant contribution from low-luminosity AGN as well as from star formation is still found. Notice that are 319 entries in this table corresponding to the 266 catalogued radio sources, due to the fact that some of these sources have multiple components. In such cases, the composite source as well as each of its components are listed as separate entries, e.g., source 7 which has 3 components (A, B and C) has 4 entries in this table. This table was created by the HEASARC in November 2008 based on the electronic version of Table 1 from the reference paper which was obtained from the ApJ web site. This is a service provided by NASA HEASARC .
This paper presents results from a survey of lambda 21-cm emission from galaxies in the Hercules cluster, A2151 and A2147. Four VLA primary beam areas were covered, a total area of 0.9 square degrees, including some 120 spiral galaxies brighter than 17.5m. The velocity resolution is 44km/s, the angular resolution 25". The detection threshold at field center is 2.6x10^8 h^{-2}M_{sun}_ in H I mass or about 1.8x10^20cm^-2^ in column density. There are 61 galaxies detected in H I, of which about 25 had been previously detected at lambda 21-cm. About ten of the detections correspond to galaxies that are very faint in the optical, m_E_>=18 or M>=-17mag-5logh. Some of these low surface brightness galaxies have very extended H I disks, with r>=15kpc. The abundance of H I is a strong function of position in the cluster, with galaxies in the south and west showing hardly any gas, and galaxies in the north and east of A2151 frequently having massive, extended gas disks. The morphology of the remnants of gas in galaxies in the south and west suggests that the intracluster medium is responsible for their H I deficiency, but there are also several dramatic galaxy mergers in progress. (c) 1997 American Astronomical Society.
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.
This survey is a deep, high resolution radio survey of a relatively small region that has particularly deep coverage
in the Sloan Digital Sky Survey. As described in the reference abstract:
This is a high-resolution radio survey of the Sloan Digital Sky Survey (SDSS) Southern Equatorial
Stripe, a.k.a., Stripe 82. This 1.4 GHz survey was conducted from 2007 to 2009 with the Very Large Array primarily in the A-configuration,
with supplemental B-configuration data to increase sensitivity to extended structure.
The survey has an angular resolution of 1.8" and achieves a median rms noise of 53 microJy/beam over 92 square degrees.
This is the deepest 1.4 GHz survey to achieve this large of an area filling in the
phase space between small&deep and large&shallow surveys.
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The astrometric accuracy of the data is excellent with errors in observed sources of 0.10" in both RA and declination.
A comparison with the SDSS DR7 Quasar Catalog confirms that the astrometry is well tied to the optical reference
frame with mean offsets of 0.02+/-0.01" in RA and 0.01+/-0.02 in declination. Provenance: TBD. This is a service of NASA HEASARC.
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.
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 .
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 .
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.
