- ID:
- ivo://CDS.VizieR/II/348
- Title:
- VISTA Variable in the Via Lactea Survey DR2
- Short Name:
- II/348
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The VVV Survey data delivered in this part of ESO Data Release 2 (DR2) are based on the VISTA/VIRCAM images that were acquired up to September 30, 2011, and processed by the Cambridge Astronomical Survey Unit (CASU). This "VVV_CAT" data release contains the single-epoch band-merged (Z, Y, J, H, Ks) catalogues associated with the VVV tile images that have already been released in the part of DR2 identified as Batch 2 of the "VVV' collection in the ESO archive. VVV_CAT contains 348 tile catalogues.
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- ID:
- ivo://CDS.VizieR/II/337
- Title:
- VISTA Variables in the Via Lactea Survey DR1
- Short Name:
- II/337
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The VVV survey targets the galactic bulge and a piece of the adjacent plane in Z, Y, J, H, and Ks. The total area of this survey is 520 square degrees and contains 355 open and 33 globular clusters. The VVV is multi-epoch in nature in order to detect a large number of variable objects and will provide > 100 carefully spaced observations for each tile. 5-sigma detection limits are Z=21.9, Y=21.2, J=20.2, H=18.2, Ks=18.1. These will be used to create a 3-dimensional map of the Bulge from well-understood distance indicators such as RR Lyrae stars. Other science drivers include the ages of stellar populations, globular cluster evolution, as well as the stellar initial mass function. The VVV Survey data delivered in this part of ESO Data Release 1 (DR1) includes the VISTA/VIRCAM paw-print and tile images that were acquired until September 30, 2010, and processed by the Cambridge Astronomical Survey Unit (CASU). This VVV_CAT data release contains the single-epoch band-merged (Z,Y,J,H,Ks) catalogues associated with the VVV tile images that have already been released in the part of DR1 identified as VVV in the ESO archive. VVV_CAT contains 269 tile catalogues.
- ID:
- ivo://CDS.VizieR/J/A+A/453/911
- Title:
- VLA and IR observations of the S235A-B region
- Short Name:
- J/A+A/453/911
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on new aspects of the star-forming region S235AB revealed through high-resolution observations at radio and mid-infrared wavelengths. Using the Very Large Array, we carried out sensitive observations of S235AB in the cm continuum (6, 3.6, 1.3, and 0.7) and in the 22GHz water maser line. These were complemented with Spitzer Space Telescope Infrared Array Camera archive data to clarify the correspondence between radio and IR sources. We made also use of newly presented data from the Medicina water maser patrol, started in 1987, to study the variability of the water masers found in the region.
- 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.
- ID:
- ivo://CDS.VizieR/J/ApJS/253/23
- Title:
- VLA 9GHz obs. of HII region candidates
- Short Name:
- J/ApJS/253/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Milky Way contains thousands of HII region candidates identified by their characteristic mid-infrared morphology, but lacking detections of ionized gas tracers such as radio continuum or radio recombination line emission. These targets thus remain unconfirmed as HII regions. With only ~2500 confirmed HII regions in the Milky Way, Galactic surveys are deficient by several thousand nebulae when compared to external galaxies with similar star formation rates. Using sensitive 9 GHz radio continuum observations with the Karl G. Jansky Very Large Array, we explore a sample of HII region candidates in order to set observational limits on the actual total population of Galactic HII regions. We target all infrared-identified "radio-quiet" sources from the Wide-field Infrared Survey Explorer Catalog of Galactic HII regions between 245{deg}>=l>=90{deg} with infrared diameters less than 80". We detect radio continuum emission from 50% of the targeted HII region candidates, providing strong evidence that most of the radio-quiet candidates are bona fide HII regions. We measure the peak and integrated radio flux densities and compare the inferred Lyman continuum fluxes using models of OB stars. We conclude that stars of approximately spectral type B2 and earlier are able to create HII regions with similar infrared and radio continuum morphologies as the more luminous HII regions created by O stars. From our 50% detection rate of "radio-quiet" sources, we set a lower limit of ~7000 for the HII region population of the Galaxy. Thus the vast majority of the Milky Way's HII regions remain to be discovered.
- ID:
- ivo://CDS.VizieR/J/ApJS/234/24
- Title:
- VLA 33GHz obs. of star-forming regions
- Short Name:
- J/ApJS/234/24
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 33GHz imaging for 112 pointings toward galaxy nuclei and extranuclear star-forming regions at ~2" resolution using the Karl G. Jansky Very Large Array (VLA) as part of the Star Formation in Radio Survey. A comparison with 33GHz Robert C. Byrd Green Bank Telescope single-dish observations indicates that the interferometric VLA observations recover 78%+/-4% of the total flux density over 25" regions (~kpc scales) among all fields. On these scales, the emission being resolved out is most likely diffuse non-thermal synchrotron emission. Consequently, on the ~30-300pc scales sampled by our VLA observations, the bulk of the 33GHz emission is recovered and primarily powered by free-free emission from discrete HII regions, making it an excellent tracer of massive star formation. Of the 225 discrete regions used for aperture photometry, 162 are extranuclear (i.e., having galactocentric radii rG>=250pc) and detected at >3{sigma} significance at 33GHz and in H{alpha}. Assuming a typical 33GHz thermal fraction of 90%, the ratio of optically-thin 33GHz to uncorrected H{alpha} star formation rates indicates a median extinction value on ~30-300pc scales of A_H{alpha}_~1.26+/-0.09mag, with an associated median absolute deviation of 0.87mag. We find that 10% of these sources are "highly embedded" (i.e., A_H{alpha}_>~3.3mag), suggesting that on average, HII regions remain embedded for <~1Myr. Finally, we find the median 33GHz continuum-to-H{alpha} line flux ratio to be statistically larger within rG<250pc relative to the outer disk regions by a factor of 1.82+/-0.39, while the ratio of 33GHz to 24{mu}m flux densities is lower by a factor of 0.45+/-0.08, which may suggest increased extinction in the central regions.
- ID:
- ivo://CDS.VizieR/J/ApJ/856/67
- Title:
- VLA 3GHz radio source catalog in the Lockman Hole
- Short Name:
- J/ApJ/856/67
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We made two new sensitive (rms noise {sigma}_n_~1{mu}Jy/beam) high-resolution ({theta}=3.0" and {theta}=0.66" FWHM) S-band (2<{nu}<4GHz) images covering a single JVLA primary beam (FWHM~14') centered on RAJ2000=10:46,DEJ2000=+59:01 in the Lockman Hole. These images yielded a catalog of 792 radio sources, 97.7+/-0.8% of which have infrared counterparts stronger than S~2{mu}Jy at {lambda}=4.5{mu}m. About 91% of the radio sources found in our previously published, comparably sensitive low-resolution ({theta}=8" FWHM) image covering the same area were also detected at 0.66" resolution, so most radio sources with S(3GHz)>~5{mu}Jy have angular structure {phi}<~0.66". The ratios of peak brightness in the 0.66" and 3" images have a distribution indicating that most {mu}Jy radio sources are quite compact, with a median Gaussian angular diameter <{phi}>=0.3"+/-0.1" FWHM and an rms scatter {sigma}_{phi}_<~0.3" of individual sizes. Most of our {mu}Jy radio sources obey the tight far-infrared/radio correlation, indicating that they are powered by star formation. The median effective angular radius enclosing half the light emitted by an exponential disk is <{rho}_e_>~<{phi}>/2.43~0.12", so the median effective radius of star-forming galaxies at redshifts z~1 is <r_e_>~1.0kpc.
- ID:
- ivo://CDS.VizieR/J/A+A/409/115
- Title:
- VLA imaging of IRAS 1 Jy ULIRG sample
- Short Name:
- J/A+A/409/115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper presents the results of a high resolution radio imaging survey of 83 of the 118 ultraluminous infrared galaxies (ULIRGs) in the IRAS 1Jy ULIRG sample (Kim & Sanders, 1998ApJS..119...41K, Veilleux et al., 2002, Cat. <J/ApJS/143/315>). We have observed these ULIRGs at 15-GHz with the Very Large Array (VLA). We find that ~75% of Seyferts (both type 1 and 2) and LINERs have radio nuclei which are compact at our 150mas resolution. The detection rate of HII nuclei is significantly lower (32%); the detections among these are preferentially HII+LINER/Seyfert composite nuclei. Among ULIRGs with multiple optical or near-IR nuclei our observations detected only one (or no) nucleus; in these the radio detection is typically towards the brightest near-IR nucleus. The compactness of the radio sources, the higher detection rates in AGN-type nuclei than HII nuclei, the preferential detection of nuclei with unresolved point sources in the near-IR, the low soft X-ray to nuclear radio luminosity ratio (arguing against thermal emission powering the radio nuclei), and the lack of correlation between radio power and H{alpha} luminosity, all support an origin of the detected radio nuclei in AGN related activity. This result is especially interesting for LINER ULIRGs for which signatures of AGNs have often been ambiguous in other wavebands. Such a high incidence of AGN would provide, for the first time, a large sample in which to study the interplay between AGN, starbursts, and galaxy mergers.
- ID:
- ivo://CDS.VizieR/J/ApJ/896/18
- Title:
- VLA imaging of obscured WISE+NVSS QSOs
- Short Name:
- J/ApJ/896/18
- Date:
- 07 Mar 2022 07:27:35
- Publisher:
- CDS
- Description:
- We present new subarcsecond-resolution Karl G. Jansky Very Large Array (VLA) imaging at 10GHz of 155 ultraluminous (Lbol~10^11.7^-10^14.2^L_{sun}_) and heavily obscured quasars with redshifts z~0.4-3. The sample was selected to have extremely red mid-infrared-optical color ratios based on data from the Wide-Field Infrared Survey Explorer (WISE) along with a detection of bright, unresolved radio emission from the NRAO VLA Sky Survey (NVSS) or Faint Images of the Radio Sky at Twenty cm Survey. Our high-resolution VLA observations have revealed that the majority of the sources in our sample (93 out of 155) are compact on angular scales <0.2 (<=1.7kpc at z~2). The radio luminosities, linear extents, and lobe pressures of our sources are similar to young radio active galactic nuclei (e.g., gigahertz-peaked spectrum [GPS] and compact steep-spectrum [CSS] sources), but their space density is considerably lower. Application of a simple adiabatic lobe expansion model suggests relatively young dynamical ages (~10^4-7yr^), relatively high ambient ISM densities (~1-10^4^cm^-3^), and modest lobe expansion speeds (~30-10000km/s). Thus, we find our sources to be consistent with a population of newly triggered, young jets caught in a unique evolutionary stage in which they still reside within the dense gas reservoirs of their hosts. Based on their radio luminosity function and dynamical ages, we estimate that only ~20% of classical large-scale FR I/II radio galaxies could have evolved directly from these objects. We speculate that the WISE-NVSS sources might first become GPS or CSS sources, of which some might ultimately evolve into larger radio galaxies.
- ID:
- ivo://CDS.VizieR/J/A+A/461/197
- Title:
- VLA NH3 observations of 5 IRAS sources
- Short Name:
- J/A+A/461/197
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The high angular resolution images with the Very Large Array (VLA) allow us to explore the general properties of protostellar cores in massive star forming regions at large distances. We observed the NH3 (J, K)=(1, 1) and (2, 2) lines toward five massive protostar candidates (IRAS 18196-1331, IRAS 18352-0148, IRAS 18361-0627, IRAS 18414-0339 and IRAS 19474+2637) with the VLA D configuration.
