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17021. VLA & Chandra obs. of IRAS20126+4104 region
ID:
ivo://CDS.VizieR/J/ApJS/219/41
Title:
VLA & Chandra obs. of IRAS20126+4104 region
Short Name:
J/ApJS/219/41
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present results from Chandra ACIS-I and Karl G. Jansky Very Large Array 6cm continuum observations of the IRAS 20126+4104 massive star-forming region. We detect 150 X-ray sources within the 17'x17' ACIS-I field, and a total of 13 radio sources within the 9.2' primary beam at 4.9GHz. Among these observations are the first 6cm detections of the central sources reported by Hofner et al. (2007A&A...465..197H), namely, I20N1, I20S, and I20var. A new variable radio source is also reported. Searching the 2MASS archive, we identified 88 near-infrared (NIR) counterparts to the X-ray sources. Only four of the X-ray sources had 6cm counterparts. Based on an NIR color-color analysis and on the Besancon simulation of Galactic stellar populations, we estimate that approximately 80 X-ray sources are associated with this massive star-forming region. We detect an increasing surface density of X-ray sources toward the massive protostar and infer the presence of a cluster of at least 43 young stellar objects within a distance of 1.2pc from the massive protostar.
17022. VLA Coma Cluster of Galaxies 1.4-GHz Source Catalog
ID:
ivo://nasa.heasarc/vlacomacat
Title:
VLA Coma Cluster of Galaxies 1.4-GHz Source Catalog
Short Name:
VLACOMACAT
Date:
01 Nov 2024
Publisher:
NASA/GSFC HEASARC
Description:
This table contains results from deep 1.4-GHz Very Large Array (VLA) radio continuum observations of two ~0.5 deg<sup>2</sup> fields in the Coma cluster of galaxies. The two fields, "Coma 1" and "Coma 3", correspond to the cluster core and the southwest infall region, and were selected on account of abundant pre-existing multiwavelength data. In their most sensitive regions, the radio data reach 0.022 mJy (22 µJy) rms per 4.4" beam, sufficient to detect (at 5-sigma) Coma member galaxies with L<sub>1.4GHz</sub> = 1.3 x 10<sup>20</sup> W Hz<sup>-1</sup> (1.3 x 10<sup>27</sup> erg s<sup>-1</sup> Hz<sup>-1</sup>). The full catalog of radio detections at and above a 4.5-sigma significance threshold is presented herein; there are 1030 of these sources which are detected at >= 5 sigma, 628 of which are within the combined Coma 1 and Coma 3 area. The authors also provide optical identifications of the radio sources using data from the Sloan Digital Sky Survey (SDSS). The depth of the radio observations allows them to detect active galactic nuclei in cluster elliptical galaxies with M<sub>r</sub> < -20.5 (AB magnitudes), including radio detections for all cluster ellipticals with M<sub>r</sub> < -21.8. At fainter optical magnitudes (-20.5 < M<sub>r</sub> <~ -19), the radio sources are associated with star-forming galaxies with star formation rates as low as 0.1M_{sun}_ yr<sup>-1</sup>. The VLA observations were performed over five days in 2006 June as program code AM868. On each of the five days, the scheduled time was centered on the transit of Coma. This table was created by the HEASARC in December 2011 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/AJ/137/4436">CDS catalog J/AJ/137/4436</a> files table2.dat ('The Radio Source Catalog') and table3.dat ('Optical Counterparts to the Radio Sources'). It does not include table4.dat ('Rejected Optical Counterparts to the Radio Sources'). This is a service provided by NASA HEASARC .
17023. VLA-COSMOS 3 GHz Large Project
ID:
ivo://CDS.VizieR/J/A+A/602/A1
Title:
VLA-COSMOS 3 GHz Large Project
Short Name:
J/A+A/602/A1
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the VLA-COSMOS 3GHz Large Project based on 384 hours of observations with the Karl G. Jansky Very Large Array (VLA) at 3GHz (10cm) toward the two square degree Cosmic Evolution Survey (COSMOS) field. The final mosaic reaches a median rms of 2.3 uJy/beam over the two square degrees at an angular resolution of 0.75". To fully account for the spectral shape and resolution variations across the broad (2GHz) band, we image all data with a multiscale, multifrequency synthesis algorithm. We present a catalog of 10,830 radio sources down to 5{sigma}, out of which 67 are combined from multiple components. Comparing the positions of our 3GHz sources with those from the Very Long Baseline Array (VLBA)-COSMOS survey, we estimate that the astrometry is accurate to 0.01" at the bright end (signal-to-noise ratio, S/N_3GHz_>20). Survival analysis on our data combined with the VLA-COSMOS 1.4GHz Joint Project catalog yields an expected median radio spectral index of {alpha}=-0.7. We compute completeness corrections via Monte Carlo simulations to derive the corrected 3GHz source counts. Our counts are in agreement with previously derived 3GHz counts based on single-pointing (0.087 square degrees) VLA data. In summary, the VLA-COSMOS 3GHz Large Project simultaneously provides the largest and deepest radio continuum survey at high (0.75") angular resolution to date, bridging the gap between last-generation and next-generation surveys.
17024. VLA-COSMOS 3 GHz Large Project. II.
ID:
ivo://CDS.VizieR/J/A+A/602/A2
Title:
VLA-COSMOS 3 GHz Large Project. II.
Short Name:
J/A+A/602/A2
Date:
21 Oct 2021
Publisher:
CDS
Description:
We study the composition of the faint radio population selected from the VLA-COSMOS 3GHz Large Project, a radio continuum survey performed at 10 cm wavelength. The survey covers a 2.6 square degree area with a mean rms of ~2.3uJy/beam, cataloging 10,830 sources above 5sigma, and enclosing the full 2 square degree COSMOS field. By combining these radio data with optical, near-infrared (UltraVISTA), and mid-infrared (Spitzer/IRAC) data, as well as X-ray data (Chandra), we find counterparts to radio sources for ~93% of the total radio sample (in the unmasked areas of the COSMOS field, i.e., those not affected by saturated or bright sources in the optical to NIR bands), reaching out to z~6. We further classify the sources as star forming galaxies or AGN based on various criteria, such as X-ray luminosity, observed MIR color, UV-FIR spectral-energy distribution, rest-frame NUV-optical color corrected for dust extinction, and radio-excess relative to that expected from the hosts' star-formation rate. We separate the AGN into sub-samples dominated by low-to-moderate and moderate-to-high radiative luminosity AGN, candidates for high- redshift analogues to local low- and high-excitation emission line AGN, respectively. We study the fractional contributions of these sub-populations down to radio flux levels of ~11uJy at 3GHz (or ~20uJy at 1.4GHz assuming a spectral index of -0.7). We find that the dominant fraction at 1.4GHz flux densities above ~200uJy is constituted of low-to-moderate radiative luminosity AGN. Below densities of ~100uJy the fraction of star-forming galaxies increases to ~60%, followed by the moderate-to-high radiative luminosity AGN (~20%), and low-to-moderate radiative luminosity AGN (~20%). Based on this observational evidence, we extrapolate the fractions down to sensitivities of the Square Kilometer Array (SKA). Our estimates suggest that at the faint flux limits to be reached by the (Wide, Deep, and UltraDeep) SKA1 surveys, a selection based only on radio flux limits can provide a simple tool to efficiently identify samples highly (>75%) dominated by star-forming galaxies.
17025. VLA-COSMOS 3-GHz Large Project Multiwavelength Counterparts Catalog
ID:
ivo://nasa.heasarc/vlacosxoid
Title:
VLA-COSMOS 3-GHz Large Project Multiwavelength Counterparts Catalog
Short Name:
VLACOSXOID
Date:
01 Nov 2024
Publisher:
NASA/GSFC HEASARC
Description:
In the reference paper, the authors study the composition of the faint radio population selected from the VLA-COSMOS 3-GHz Large Project, a radio continuum survey performed at 10-cm wavelength. The survey covers a 2.6 square degree area with a mean rms of ~2.3 µJy/beam (µJy/beam), cataloguing 10,830 sources above 5 sigma, and enclosing the full 2 square degree COSMOS field. By combining these radio data with optical, near-infrared (UltraVISTA), and mid-infrared (Spitzer/IRAC) data, as well as X-ray data (Chandra), the authors find counterparts to radio sources for ~93% of the total radio sample in the unmasked areas of the COSMOS field, i.e., those not affected by saturated or bright sources in the optical to near-IR (NIR) bands, reaching out to z ~ 6. They further classify the sources as star-forming galaxies or AGN based on various criteria, such as X-ray luminosity, observed mid-infrare (MIR) color, UV-far-infrared (FIR) spectral-energy distribution (SED), rest-frame near-ultraviolet (NUV)-optical color corrected for dust extinction, and radio-excess relative to that expected from the the hosts' star-formation rate. The authors separate the AGN into sub-samples dominated by low-to-moderate and moderate-to-high radiative luminosity AGN, i.e., candidates for high-redshift analogs to local low- and high-excitation emission line AGN, respectively. They study the fractional contributions of these sub-populations down to radio flux levels of ~11 uJy at 3 GHz (or ~20 uJy at 1.4 GHz assuming a spectral index of -0.7), and find that the dominant fraction at 1.4 GHz flux densities above ~200 uJy is constituted of low-to-moderate radiative luminosity AGN MLAGN). Below densities of ~100 uJy the fraction of star-forming galaxies (SFG) increases to ~60%, followed by the moderate-to-high radiative luminosity AGN (HLAGN) with ~20%, and MLAGN with ~20%. Based on this observational evidence, the authors extrapolate the fractions down to sensitivities of the Square Kilometer Array (SKA). Their estimates suggest that at the faint flux limits to be reached by the (Wide, Deep, and UltraDeep) SKA1 surveys, a selection based only on radio flux limits can provide a simple tool to efficiently identify samples highly (>75%) dominated by star-forming galaxies. This table contains the full list of 9,161 optical-MIR counterparts collected over the largest unmasked area accessible to each catalog, being 1.77, 1.73, and 2.35 square degrees for COSMOS2015, i-band, and IRAC catalogs, respectively. The catalog lists the counterpart IDs, properties, as well as the individual criteria used in this work to classify these radio sources. The authors note that complete, non-overlapping samples within a well defined, effective area of 1.77 square degrees (COSMOS2015 masked area flag_C15 = 0, can be formed by combining (i) HLAGN, MLAGN, and clean SFG samples, or, alternatively, (ii) the radio-excess and no-radio-excess samples. This table was created by the HEASARC in July 2017 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/602/A2">CDS Catalog J/A+A/602/A2</a> file table1.dat, the VLA-COSMOS 3-GHz Large Project multiwavelength counterpart catalog. This is a service provided by NASA HEASARC .
17026. VLA-COSMOS 3-GHz Large Project Source Catalog
ID:
ivo://nasa.heasarc/vlacos3ghz
Title:
VLA-COSMOS 3-GHz Large Project Source Catalog
Short Name:
VLACOS3GHZ
Date:
01 Nov 2024
Publisher:
NASA/GSFC HEASARC
Description:
This table contains some of the results from the VLA-COSMOS 3-GHz Large Project based on 384 hours of observations with the Karl G. Jansky Very Large Array (VLA) at 3 GHz (10 cm) toward the 2 square degree Cosmic Evolution Survey (COSMOS) field. The final mosaic reaches a median rms of 2.3 µJy (µJy) beam<sup>-1</sup> over the 2 square degrees at an angular resolution of 0.75 arcseconds. To fully account for the spectral shape and resolution variations across the broad (2-GHz) band, the authors imaged all the data with a multiscale, multifrequency synthesis algorithm. In this table, the catalog of 10,830 radio sources down to 5 sigma is presented, out of which 67 are combined from multiple components. Comparing the positions of these 3-GHz sources with those from the Very Long Baseline Array (VLBA)-COSMOS survey, the authors estimate that the astrometry is accurate to 0.01 arcseconds at the bright end (signal-to-noise ratio, S/N<sub>3GHz</sub> > 20). Survival analysis on these data combined with the VLA-COSMOS 1.4-GHz Joint Project catalog yields an expected median radio spectral index alpha = -0.7. The authors compute completeness corrections via Monte Carlo simulations to derive the corrected 3-GHz source counts. Their counts are in agreement with previously derived 3-GHz counts based on single-pointing (0.087 square degrees) VLA data. In summary, the VLA-COSMOS 3-GHz Large Project simultaneously provides the largest and deepest radio continuum survey at high (0.75") angular resolution to date, bridging the gap between last-generation and next-generation surveys. The catalog contains sources selected down to a 5-sigma (where sigma ~2.3 µJy/beam) threshold. This catalog can be used for statistical analyses, accompanied with the corrections given in the data & catalog release paper. All completeness and bias corrections and source counts presented in the paper were calculated using this sample. The total fraction of spurious sources in the COSMOS 2 sq.deg. field is below 2.7% within this catalog. However, an increase of spurious sources up to 24% at 5.0 < S/N < 5.5 is present (for details see Sec. 5.2., Fig. 17 and Table 3 of the reference paper). A subsample with a minimal spurious source fraction can be selected by requiring an additional cutoff S/N >= 5.5 for single component sources (MULTI=0). The total fraction of spurious sources in the COSMOS 2 sq.deg. field within such a selected sample is below 0.4%, and the fraction of spurious sources is below 3% even at the lowest S/N of 5.5. This table was created by the HEASARC in June 2017 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/602/A1">CDS Catalog J/A+A/602/A1</a> file table1.dat, the VLA-COSMOS 3-GHz radio source catalog. This is a service provided by NASA HEASARC .
17027. VLA-COSMOS 3GHz sources average radio SED
ID:
ivo://CDS.VizieR/J/A+A/621/A139
Title:
VLA-COSMOS 3GHz sources average radio SED
Short Name:
J/A+A/621/A139
Date:
21 Oct 2021
Publisher:
CDS
Description:
We construct the average radio spectral energy distribution (SED) of highly star-forming galaxies (HSFGs) up to z~4. Infrared and radio luminosities are bound by a tight correlation that is defined by the so-called q parameter. This infrared-radio correlation provides the basis for the use of radio luminosity as a star-formation tracer. Recent stacking and survival analysis studies find q to be decreasing with increasing redshift. It was pointed out that a possible cause of the redshift trend could be the computation of rest-frame radio luminosity via a single power-law assumption of the star-forming galaxies' (SFGs) SED. To test this, we constrained the shape of the radio SED of a sample of HSFGs. To achieve a broad rest-frame frequency range, we combined previously published Very Large Array observations of the COSMOS field at 1.4GHz and 3GHz with unpublished Giant Meterwave Radio Telescope (GMRT) observations at 325MHz and 610MHz by employing survival analysis to account for non-detections in the GMRT maps. We selected a sample of HSFGs in a broad redshift range (z{in}[0.3,4], SFR>=100M_{sun}_/yr) and constructed the average radio SED. By fitting a broken power-law, we find that the spectral index changes from {sigma}_1_=0.42+/-0.06 below a rest-frame frequency of 4.3GHz to {sigma}_2_=0.94+/-0.06 above 4.3GHz. Our results are in line with previous low-redshift studies of HSFGs (SFR>10M_{sun}_/yr) that show the SED of HSFGs to differ from the SED found for normal SFGs (SFR<10M_{sun}}/yr). The difference is mainly in a steeper spectrum around 10GHz, which could indicate a smaller fraction of thermal free-free emission. Finally, we also discuss the impact of applying this broken power-law SED in place of a simple power-law in K-corrections of HSFGs and a typical radio SED for normal SFGs drawn from the literature. We find that the shape of the radio SED is unlikely to be the root cause of the q-z trend in SFGs.
17028. VLA-COSMOS Large Project 1.4-GHz Source Catalog
ID:
ivo://nasa.heasarc/vlacosmos
Title:
VLA-COSMOS Large Project 1.4-GHz Source Catalog
Short Name:
VLACOSMOS
Date:
01 Nov 2024
Publisher:
NASA/GSFC HEASARC
Description:
The international COSMOS (Cosmic Evolution) survey (Scoville et al. 2007, ApJS, 172, 1) is a panchromatic imaging and spectroscopic survey of a 1.4 degree by 1.4 degree field designed to probe galaxy and SMBH (supermassive black hole) evolution as a function of cosmic environment. One major aspect of the COSMOS survey is the Hubble Space Telescope (HST) Treasury Project (Scoville et al. 2007, ApJS, 172, 38), entailing the largest ever allocation of HST telescope time. The equatorial location of the COSMOS field offers the critical advantage of allowing major observatories from both hemispheres to join forces in this endeavor. State-of-the-art imaging data at all wavelengths (X-ray to centimeter, plus large optical spectroscopic campaigns using the VLT VIMOS and the Magellan IMACS instruments (Lilly et al. 2007; Impey et al. 2007; Trump et al. 2007) have been or are currently being obtained for the COSMOS field. These make the COSMOS field an excellent resource for observational cosmology and galaxy evolution in the important redshift range z ~ 0.5 - 3, a time span covering ~ 75% of the lifetime of the universe. The VLA-COSMOS Large Project produced a catalog of 3643 radio sources found in the 2 square degrees COSMOS field at 1.4 GHz with a signal-to-noise threshold S/N &gt;= 4.5. The observations in the VLA A and C configurations resulted in a resolution of 1.5&quot; by 1.4&quot; and a mean rms noise of ~ 10.5 &micro;Jy (&micro;Jy) beam&lt;sup&gt;-1&lt;/sup&gt; in the central 1 deg&lt;sup&gt;2&lt;/sup&gt;, and of 15 uJy in the 2 deg&lt;sup&gt;2&lt;/sup&gt; field. Eighty radio sources are clearly extended consisting of multiple components, and most of them appear to be double-lobed radio galaxies. The astrometry of the catalog has been thoroughly tested, and the uncertainty in the relative and absolute astrometry are 130 and &lt; 55 mas, respectively. This table was created by the HEASARC in September 2007 based on the electronic version of Table 3 from the reference paper which was obtained from the ApJ web site. This is a service provided by NASA HEASARC .
17029. VLA-COSMOS Project 1.4-GHz Joint Source Catalog
ID:
ivo://nasa.heasarc/vlacosmjsc
Title:
VLA-COSMOS Project 1.4-GHz Joint Source Catalog
Short Name:
VLACOSMJSC
Date:
01 Nov 2024
Publisher:
NASA/GSFC HEASARC
Description:
In the context of the VLA-COSMOS Deep project, additional VLA A array observations at 1.4 GHz were obtained for the central degree of the COSMOS field and combined with the existing data from the VLA-COSMOS Large project. A newly constructed Deep mosaic with a resolution of 2.5 arcseconds was used to search for sources down to 4 sigma with 1 sigma ~ 12 &micro;Jy beam&lt;sup&gt;-1&lt;/sup&gt; in the central 50&#39; x 50&#39;. This new catalog is combined with the catalog from the Large project (obtained at 1.5&quot; x 1.4&quot; resolution) to construct a new Joint catalog. All sources listed in the new Joint catalog have peak flux densities of &gt;= 5 sigma at 1.5&quot; and/or 2.5&quot; resolution to account for the fact that a significant fraction of sources at these low flux levels are expected to be slightly resolved at 1.5&quot; resolution. All properties listed in the Joint catalog, such as peak flux density, integrated flux density, and source size, are determined in the 2.5&quot; resolution Deep image. In addition, the Joint catalog contains 43 newly identified multi-component sources. This table was created by the HEASARC in June 2010 based on the electronic version of Table 3 from the reference paper which was obtained from the ApJ web site. This is a service provided by NASA HEASARC .
17030. VLA-COSMOS survey. II.
ID:
ivo://CDS.VizieR/J/ApJS/172/46
Title:
VLA-COSMOS survey. II.
Short Name:
J/ApJS/172/46
Date:
21 Oct 2021
Publisher:
CDS
Description:
The VLA-COSMOS Large Project is described and its scientific objective is discussed. We present a catalog of 3600 radio sources found in the 2deg^2^ COSMOS field at 1.4GHz. The observations in the VLA A and C configuration resulted in a resolution of 1.5"x1.4" and a mean rms noise of ~10.5(15)uJy/beam in the central 1(2)deg^2^. Eighty radio sources are clearly extended consisting of multiple components, and most of them appear to be double-lobed radio galaxies. The astrometry of the catalog has been thoroughly tested, and the uncertainty in the relative and absolute astrometry are 130 and <55mas, respectively.

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