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1861. VSOP 5 GHz AGN Survey. III
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.
1862. VSOP 5GHz AGN Survey. IV
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.
1863. VSOP 5GHz AGN survey V.
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.
1864. VVDS-VLA Deep Field: 610 MHz catalog
ID:
ivo://CDS.VizieR/J/A+A/463/519
Title:
VVDS-VLA Deep Field: 610 MHz catalog
Short Name:
J/A+A/463/519
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the 5 sigma catalogue at 610MHz of the VVDS-VLA deep field obtained from GMRT observations. The field is located at 02:26:00-04:30:00 (J2000) and covers a 1 square degree area. The GMRT observations imaged the whole 1 square degree field with an angular resolution of 6 arcsec and an average sensitivity of about 50 microJy. The catalogue lists 514 radio sources 17 of which are fitted with multiple components.
1865. Warm dust near methanol masers
ID:
ivo://CDS.VizieR/J/A+A/410/597
Title:
Warm dust near methanol masers
Short Name:
J/A+A/410/597
Date:
21 Oct 2021
Publisher:
CDS
Description:
Continuum emission at 450 and 850{mu}m from warm dust has been mapped in the fields of 71 methanol masers. Within these fields lie 30 centimetre-wave radio continuum sources and an additional 13 methanol maser sites. Sub-mm emission is detected at all but one of the maser sites, confirming the association of methanol maser emission with deeply embedded objects. Measured bolometric luminosities confirm that methanol maser emission is an excellent signpost of high-mass star formation. Examples of nearby isolated maserless dust cores may be harbouring massive protostars at an earlier evolutionary stage.
1866. Water and methanol masers in G75.78+0.34
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.
1867. Water and Methanol masers in NGC 6334I(N)
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.
1868. Water maser and NH_3_ survey of GLIMPSE EGOs
ID:
ivo://CDS.VizieR/J/ApJ/764/61
Title:
Water maser and NH_3_ survey of GLIMPSE EGOs
Short Name:
J/ApJ/764/61
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of a Nobeyama 45m H_2_O maser and NH_3_ survey of all 94 northern GLIMPSE extended green objects (EGOs), a sample of massive young stellar objects (MYSOs) identified based on their extended 4.5{mu}m emission. We observed the NH_3_(1,1), (2,2), and (3,3) inversion lines, and detected emission toward 97%, 63%, and 46% of our sample, respectively (median rms~50mK). The H_2_O maser detection rate is 68% (median rms~0.11Jy). The derived H_2_O maser and clump-scale gas properties are consistent with the identification of EGOs as young MYSOs. To explore the degree of variation among EGOs, we analyze subsamples defined based on mid-infrared (MIR) properties or maser associations. H_2_O masers and warm dense gas, as indicated by emission in the higher-excitation NH_3_ transitions, are most frequently detected toward EGOs also associated with both Class I and II CH_3_OH masers. Ninety-five percent (81%) of such EGOs are detected in H_2_O (NH_3_(3,3)), compared to only 33% (7%) of EGOs without either CH_3_OH maser type. As populations, EGOs associated with Class I and/or II CH_3_OH masers have significantly higher NH_3_ line widths, column densities, and kinetic temperatures than EGOs undetected in CH_3_OH maser surveys. However, we find no evidence for statistically significant differences in H_2_O maser properties (such as maser luminosity) among any EGO subsamples. Combining our data with the 1.1mm continuum Bolocam Galactic Plane Survey, we find no correlation between isotropic H_2_O maser luminosity and clump number density. H_2_O maser luminosity is weakly correlated with clump (gas) temperature and clump mass.
1869. Water maser data of 380 galaxies
ID:
ivo://CDS.VizieR/J/A+A/641/A162
Title:
Water maser data of 380 galaxies
Short Name:
J/A+A/641/A162
Date:
21 Oct 2021
Publisher:
CDS
Description:
Water megamaser emission at 22GHz has proven to be a powerful tool for astrophysical studies of active galactic nuclei (AGN) because it allows an accurate determination of the mass of the central black hole and of the accretion disc geometry and dynamics. However, after searches among thousands of galaxies, only ~200 of them have shown such spectroscopic features, most of them of uncertain classification. In addition, the physical and geometrical conditions under which a maser activates are still unknown. We characterize the occurrence of water maser emission in an unbiased sample of AGN by investigating the relation with the X-ray properties and the possible favourable geometry that is required to detect water maser. We searched for 22GHz maser emission in a hard X-ray selected sample of AGN, taken from the INTEGRAL/IBIS survey above 20keV. Only half of the 380 sources in the sample have water maser data. We also considered a volume-limited sub-sample of 87 sources, for which we obtained new observations with the Green Bank and Effelsberg telescopes (for 35 sources). We detected one new maser and increased its radio coverage to 75%. The detection rate of water maser emission in the total sample is 15+/-3%. This fraction increases to 19+/-5% for the complete sub-sample, especially when we consider type 2 (22+/-5% and 31+/-10% for the total and complete samples, respectively) and Compton-thick AGN (56+/-18% and 50+/-35% for the total and complete samples, respectively). No correlation is found between water maser and X-ray luminosity. We note that all types of masers (disc and jet) are associated with hard X-ray selected AGN. These results demonstrate that the hard X--ray selection may significantly enhance the maser detection efficiency over comparably large optical or infrared surveys. A possible decline in detection fraction with increasing luminosity might suggest that an extremely luminous nuclear environment does not favour maser emission. The large fraction of CT AGN with water maser emission could be explained in terms of geometrical effects. The maser medium would then be the very edge-on portion of the obscuring medium.
1870. Water maser emission in five AGNs
ID:
ivo://CDS.VizieR/J/ApJ/652/136
Title:
Water maser emission in five AGNs
Short Name:
J/ApJ/652/136
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the discovery of water maser emission in five active galactic nuclei (AGNs) with the 100m Green Bank Telescope (GBT). The positions of the newly discovered masers, measured with the VLA, are consistent with the optical positions of the host nuclei to within 1{sigma} (0.3" radio and 1.3" optical) and most likely mark the locations of the embedded central engines. The spectra of three sources, 2MASX J08362280+3327383, NGC 6264, and UGC 09618 NED02 (PGC 053432), display the characteristic spectral signature of emission from an edge-on accretion disk with maximum orbital velocity of ~700, ~800, and ~1300km/s, respectively. We also present a GBT spectrum of a previously known source, Mrk 0034, and interpret the narrow Doppler components reported here as indirect evidence that the emission originates in an edge-on accretion disk with orbital velocity of ~500km/s .