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- 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/640/A109
- Title:
- VLA and XMM-EPIX maps of M83
- Short Name:
- J/A+A/640/A109
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Reconnection heating has been considered as a potential source of the heating of the interstellar medium. In some galaxies, significant polarised radio emission has been found between the spiral arms. This emission has a form of 'magnetic arms' that resembles the spiral structure of the galaxy. Reconnection effects could convert some of the energy of the turbulent magnetic field into the thermal energy of the surrounding medium, leaving more ordered magnetic fields, as is observed in the magnetic arms. Sensitive radio and X-ray data for the grand-design spiral galaxy M 83 are used for a detailed analysis of the possible interactions of magnetic fields with hot gas, including a search for signatures of gas heating by magnetic reconnection effects. Magnetic field strengths and energies derived from the radio emission are compared with the parameters of the hot gas calculated from the model fits to sensitive X-ray spectra of the hot gas emission. The available X-ray data allowed us to distinguish two thermal components in the halo of M 83. We found slightly higher average temperatures of the hot gas in the interarm regions, which results in higher energies per particle and is accompanied by a decrease in the energy density of the magnetic fields. The observed differences in the energy budget between the spiral arms and the interarm regions suggest that, similar to the case of another spiral galaxy NGC 6946, we may be observing hints for gas heating by magnetic reconnection effects in the interarm regions. These effects, which act more efficiently on the turbulent component of the magnetic field, are expected to be stronger in the spiral arms. However, with the present data it is only possible to trace them in the interarm regions, where the star formation and the resulting turbulence is low.
- ID:
- ivo://CDS.VizieR/J/ApJS/188/178
- Title:
- VLA 1.4GHz observations of GOODS-North field
- Short Name:
- J/ApJS/188/178
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe deep, new, wide-field radio continuum observations of the Great Observatories Origins Deep Survey-North field. The resulting map has a synthesized beam size of ~1.7" and an rms noise level of ~3.9uJy/beam near its center and ~8uJy/beam at 15' from phase center. We have cataloged 1230 discrete radio emitters, within a 40'x40' region, above a 5{sigma} detection threshold of ~20uJy at the field center. New techniques, pioneered by Owen & Morrison, have enabled us to achieve a dynamic range of 6800:1 in a field that has significantly strong confusing sources. We compare the 1.4GHz (20cm) source counts with those from other published radio surveys. Our differential counts are nearly Euclidean below 100uJy with a median source diameter of ~1.2". This adds to the evidence presented by Owen & Morrison that the natural confusion limit may lie near 1uJy. If the Euclidean slope of the counts continues down to the natural confusion limit as an extrapolation of our logN-logS, this indicates that the cutoff must be fairly sharp below 1uJy else the cosmic microwave background temperature would increase above 2.7K at 1.4GHz.
- 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/ApJS/179/114
- Title:
- VLA 1.4GHz survey of E-CDF-S
- Short Name:
- J/ApJS/179/114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have observed the Extended Chandra Deep Field-South (E-CDF-S) using a mosaic of six deep Very Large Array (VLA) pointings at 1.4GHz. In this paper, we present the survey strategy, description of the observations, and the first data release. The observations were performed during June through September of 2007 and included from 15 to 17 "classic" VLA antennas and 6 to 11 that had been retrofitted for the Expanded VLA (EVLA). The first data release consists of a 34.1'x34.1' image and the attendant source catalog. The image achieves an rms sensitivity of 6.4{mu}Jy per 2.8"x1.6" beam in its deepest regions, with a typical sensitivity of 8uJy. The catalog is conservative in that it only lists sources with peak flux densities greater than seven times the local rms noise, yet it still contains 464 sources. Nineteen of these are complex sources consisting of multiple components. Cross matching of the catalog to prior surveys of the E-CDF-S confirms the linearity of the flux density calibration, albeit with a slight possible offset (a few percent) in scale. Improvements to the data reduction and source catalog are ongoing, and we intend to produce a second data release in 2009 January.
- ID:
- ivo://CDS.VizieR/J/ApJS/205/13
- Title:
- VLA 1.4GHz survey of ECDF-S (DR2)
- Short Name:
- J/ApJS/205/13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Deep radio observations at 1.4GHz for the Extended Chandra Deep Field South were performed in 2007 June through September and presented in a first data release. The survey was made using six separate pointings of the Very Large Array with over 40hr of observation per pointing. In the current paper, we improve on the data reduction to produce a second data release (DR2) mosaic image. This DR2 image covers an area of about a third of a square degree, reaches a best rms sensitivity of 6uJy, and has a typical sensitivity of 7.4uJy per 2.8" by 1.6" beam. We also present a more comprehensive catalog, including sources down to peak flux densities of five or more times the local rms noise along with information on source sizes and relevant pointing data. We discuss in some detail the consideration of whether sources are resolved under the complication of a radio image created as a mosaic of separate pointings each suffering some degree of bandwidth smearing, and the accurate evaluation of the flux densities of such sources. Finally, the radio morphologies and optical/near-IR counterpart identifications are used to identify 17 likely multiple-component sources and arrive at a catalog of 883 radio sources, which is roughly double the number of sources contained in the first data release.
- ID:
- ivo://CDS.VizieR/J/ApJS/124/285
- Title:
- VLA Images of Extragalactic Objects
- Short Name:
- J/ApJS/124/285
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Maps of 212 extragalactic radio sources at 4.9 GHz are shown in Stokes I along with linear polarization vectors. The objects have a declination range of 0 degrees to -35 degrees and were chosen from the Hewitt & Burbidge quasar catalog with a spectral index less than -0.5 and the NVSS survey with a minimum 1.4 GHz flux density greater than 300 mJy. The observations were made with the Very Large Array in its B configuration, and the images have a typical resolution of 2 arcseconds. One hundred ninety-five objects were resolved; 108 of the sources are quasars, and another 51 have been identified as galaxies.
- 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.
