- ID:
- ivo://CDS.VizieR/J/A+A/425/99
- Title:
- VLBI and VLA obs. of Seyfert galaxies
- Short Name:
- J/A+A/425/99
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained mas-scale resolution very long baseline interferometry (VLBI) images of a sample of Seyfert 1 and Seyfert 2 galaxies at 5GHz (wavelength, {lambda}=6cm). The Seyferts of the two types were chosen to be matched in several orientation-independent properties, primarily in order to rigorously test predictions of the unified scheme. We detected all the 15 objects that we observed. In this paper we describe the observations and data reduction procedures, and present the VLBI radio images as well as simultaneous Very Large Array images that we obtained for these 15 Seyferts.
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- ID:
- ivo://CDS.VizieR/J/ApJS/155/33
- Title:
- VSOP 5 GHz AGN Survey. III
- Short Name:
- J/ApJS/155/33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The VLBI Space Observatory Programme (VSOP) mission is a Japanese-led project to study radio sources with sub-milliarcsec resolution using an orbiting 8m telescope, HALCA, along with global arrays of Earth-based telescopes. Approximately 25% of the observing time is devoted to a survey of compact active galactic nuclei (AGNs) that are stronger than 1Jy at 5GHz - the VSOP AGN Survey. This paper, the third in the series, presents the results from the analysis of the first 102 Survey sources.
- ID:
- ivo://CDS.VizieR/J/ApJ/616/110
- Title:
- VSOP 5GHz AGN Survey. IV
- Short Name:
- J/ApJ/616/110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The VLBI Space Observatory Programme (VSOP) mission is a Japanese-led project to study radio sources with submilliarcsecond angular resolution, using an orbiting 8m telescope on board the satellite HALCA with a global Earth-based array of telescopes. A major program is the 5GHz VSOP Survey Program, which we supplement here with Very Long Baseline Array observations to produce a complete and flux density-limited sample. Using statistical methods of analysis of the observed visibility amplitude versus projected (u, v) spacing, we have determined the angular size and brightness temperature distribution of bright radio emission from active galactic nuclei.
- ID:
- ivo://CDS.VizieR/J/ApJS/175/314
- Title:
- VSOP 5GHz AGN survey V.
- Short Name:
- J/ApJS/175/314
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In 1997 February, the Japanese radio astronomy satellite HALCA was launched to provide the space-bourne element for the VLBI Space Observatory Program (VSOP) mission. Approximately 25% of the mission time was dedicated to the VSOP survey of bright compact active galactic nuclei (AGNs) at 5GHz. This paper, the fifth in the series, presents images and models for the remaining 140 sources not included in the third paper in the series, which contained 102 sources. For most sources, the plots of the (u,v) coverage, the visibility amplitude versus (u,v) distance, and the high-resolution image are presented. Model fit parameters to the major radio components are determined, and the brightness temperature of the core component for each source is calculated. The brightness temperature distributions for all of the sources in the VSOP AGN survey are discussed.
- ID:
- ivo://CDS.VizieR/J/ApJ/766/114
- Title:
- Water and methanol masers in G75.78+0.34
- Short Name:
- J/ApJ/766/114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present subarcsecond observations toward the massive star-forming region G75.78+0.34. We used the Very Large Array to study the centimeter continuum and H_2_O and CH_3_OH maser emission, and the Owens Valley Radio Observatory and Submillimeter Array to study the millimeter continuum and recombination lines (H40{alpha} and H30{alpha}). We found radio continuum emission at all wavelengths, coming from three components: (1) a cometary ultracompact (UC) H II region with an electron density ~3.7x10^4^/cm3, excited by a B0 type star, and with no associated dust emission; (2) an almost unresolved UCH II region (EAST), located ~6" to the east of the cometary UCH II region, with an electron density ~1.3x10^5^/cm3, and associated with a compact dust clump detected at millimeter and mid-infrared wavelengths; and (3) a compact source (CORE), located ~2" to the southwest of the cometary arc, with a flux density increasing with frequency, and embedded in a dust condensation of 30M_{sun}_. The CORE source is resolved into two compact and unresolved sources which can be well fit by two homogeneous hypercompact H II regions each one photoionized by a B0.5 zero-age main sequence star, or by free-free radiation from shock-ionized gas resulting from the interaction of a jet/outflow system with the surrounding environment. The spatial distribution and kinematics of water masers close to the CORE-N and S sources, together with excess emission at 4.5{mu}m and the detected dust emission, suggest that the CORE source is a massive protostar driving a jet/outflow.
- ID:
- ivo://CDS.VizieR/J/ApJ/707/1
- Title:
- Water and Methanol masers in NGC 6334I(N)
- Short Name:
- J/ApJ/707/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a high-resolution, multi-wavelength study of the massive protostellar cluster NGC 6334 I(N) that combines new spectral line data from the Submillimeter Array (SMA) and VLA with a re-analysis of archival VLA continuum data, Two Micron All Sky Survey and Spitzer images. As shown previously, the brightest 1.3mm source SMA1 contains substructure at subarcsecond resolution, and we report the first detection of SMA1b at 3.6cm along with a new spatial component at 7mm (SMA1d). We find SMA1 (aggregate of sources a, b, c, and d) and SMA4 to be comprised of free-free and dust components, while SMA6 shows only dust emission. Our 1.5" resolution 1.3mm molecular line images reveal substantial hot-core line emission toward SMA1 and to a lesser degree SMA2. We find CH_3_OH rotation temperatures of 165+/-9K and 145+/-12K for SMA1 and SMA2, respectively. We estimate a diameter of 1400AU for the SMA1 hot-core emission, encompassing both SMA1b and SMA1d, and speculate that these sources comprise a >~800AU separation binary that may explain the previously suggested precession of the outflow emanating from the SMA1 region. Compact line emission from SMA4 is weak, and none is seen toward SMA6. The LSR velocities of SMA1, SMA2, and SMA4 all differ by 1-2km/s. Outflow activity from SMA1, SMA2, SMA4, and SMA6 is observed in several molecules including SiO(5-4) and IRAC 4.5um emission; 24um emission from SMA4 is also detected. Eleven water maser groups are detected, eight of which coincide with SMA1, SMA2, SMA4, and SMA6, while two others are associated with the Sandell source SM2. We also detect a total of 83 Class I CH_3_OH 44GHz maser spots which likely result from the combined activity of many outflows. Our observations paint the portrait of multiple young hot cores in a protocluster prior to the stage where its members become visible in the near-infrared.
- ID:
- ivo://CDS.VizieR/J/A+A/632/A38
- Title:
- Westerlund 1 reduced images of radio emission
- Short Name:
- J/A+A/632/A38
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Massive stars and their stellar winds are important for a number of feedback processes. The mass lost in the stellar wind can help determine the end-point of the star as a neutron star (NS) or a black hole (BH). However, the impact of mass loss on the post-main sequence evolutionary stage of massive stars is not well understood. Westerlund 1 is an ideal astrophysical laboratory in which to study massive stars and their winds in great detail over a large range of different evolutionary phases. We aim to study the radio emission from Westerlund 1, in order to measure radio fluxes from the population of massive stars, and determine the mass-loss rates and spectral indices where possible. Observations were carried out in 2015 and 2016 with the Australia Telescope Compact Array (ATCA) at 5.5 and 9GHz using multiple configurations, with maximum baselines ranging from 750m to 6km. Thirty stars are detected in the radio from the fully concatenated dataset, ten of which are Wolf Rayet stars (WRs) (predominantly late type WN stars), five yellow hypergiants (YHGs), four red supergiants (RSGs), one luminous blue variable (LBV), the sgB[e] star W9, and several OB supergiants. New source detections in the radio are found for the WR stars, and five OB supergiants. These detections lead to evidence for three new OB supergiant binary candidates, which is inferred from derived spectral index limits. Spectral indices and index limits were determined for massive stars in Westerlund 1. For cluster members found to have partially optically thick emission, mass-loss rates were calculated. Under the approximation of a thermally emitting stellar wind and a steady mass-loss rate, clumping ratios were then estimated for eight WRs. Diffuse radio emission was detected throughout the cluster. Detections of knots of radio emission with no known counterparts indicate the highly clumped structure of this intra-cluster medium, likely shaped by a dense cluster wind.
- ID:
- ivo://CDS.VizieR/J/ApJS/180/283
- Title:
- WMAP five-year source catalog
- Short Name:
- J/ApJS/180/283
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the list of point sources found in the Wilkinson Microwave Anisotropy Probe (WMAP) five-year maps. The technique used in the first-year and three-year analyses now finds 390 point sources, and the five-year source catalog is complete for regions of the sky away from the Galactic plane to a 2Jy limit, with SNR>4.7 in all bands in the least covered parts of the sky. The noise at high frequencies is still mainly radiometer noise, but at low frequencies the cosmic microwave background (CMB) anisotropy is the largest uncertainty. A separate search of CMB-free V-W maps finds 99 sources of which all but one can be identified with known radio sources. The sources seen by WMAP are not strongly polarized. Many of the WMAP sources show significant variability from year to year, with more than a 2:1 range between the minimum and maximum fluxes.
- ID:
- ivo://CDS.VizieR/J/A+A/567/L5
- Title:
- W3(OH) high angular resolution 7mm images
- Short Name:
- J/A+A/567/L5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recent high angular resolution radio observations of the ultracompact Hii region W3(OH) confirm the presence of an extremely compact (0.05"), time-variable source near its center. We use new, sensitive high angular resolution observations of radio continuum and recombination lines to study the compact source in W3(OH) and the ultracompact HII region itself. We reduced and analyzed extensive Jansky Very Large Array observations of W3(OH) in the continuum at 41.0GHz and in the H54{alpha} and He54{alpha} lines.
- ID:
- ivo://CDS.VizieR/J/ApJ/779/133
- Title:
- X-ray & radio fluxes of unassociated 2FGL sources
- Short Name:
- J/ApJ/779/133
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Fermi Gamma-Ray Space Telescope has been detecting a wealth of sources where the multiwavelength counterpart is either inconclusive or missing altogether. We present a combination of factors that can be used to identify multiwavelength counterparts to these Fermi unassociated sources. This approach was used to select and investigate seven bright, high-latitude unassociated sources with radio, UV, X-ray, and {gamma}-ray observations. As a result, four of these sources are candidates to be active galactic nuclei, and one to be a pulsar, while two do not fit easily into these known categories of sources. The latter pair of extraordinary sources might reveal a new category subclass or a new type of {gamma}-ray emitter. These results altogether demonstrate the power of a multiwavelength approach to illuminate the nature of unassociated Fermi sources.
