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841. 1.5Jy MOJAVE AGN sample and 3FGL data
ID:
ivo://CDS.VizieR/J/ApJ/810/L9
Title:
1.5Jy MOJAVE AGN sample and 3FGL data
Short Name:
J/ApJ/810/L9
Date:
21 Oct 2021
Publisher:
CDS
Description:
We use the complete MOJAVE 1.5Jy sample of active galactic nuclei (AGNs) to examine the gamma-ray detection statistics of the brightest radio-loud blazars in the northern sky. We find that 23% of these AGNs were not detected above 0.1GeV by the Fermi-LAT during the four-year 3FGL catalog period partly because of an instrumental selection effect and partly due to their lower Doppler boosting factors. Blazars with synchrotron peaks in their spectral energy distributions located below 10^13.4^Hz also tend to have high-energy peaks that lie below the 0.1GeV threshold of the LAT, and are thus less likely to be detected by Fermi. The non-detected AGNs in the 1.5Jy sample also have significantly lower 15GHz radio modulation indices and apparent jet speeds, indicating that they have lower than average Doppler factors. Since the effective amount of relativistic Doppler boosting is enhanced in gamma-rays (particularly in the case of external inverse-Compton scattering), this makes them less likely to appear in the 3FGL catalog. Based on their observed properties, we have identified several bright radio-selected blazars that are strong candidates for future detection by Fermi.
842. 1Jy northern AGN sample
ID:
ivo://CDS.VizieR/J/A+A/596/A106
Title:
1Jy northern AGN sample
Short Name:
J/A+A/596/A106
Date:
21 Oct 2021
Publisher:
CDS
Description:
Continuum spectra covering centimetre to submillimetre wavelengths are presented for a northern sample of 104 extragalactic radio sources, mainly active galactic nuclei, based on four-epoch Planck data. The nine Planck frequencies, from 30 to 857GHz, are complemented by a set of simultaneous ground-based radio observations between 1.1 and 37GHz. The single-survey Planck data confirm that the flattest high-frequency radio spectral indices are close to zero, indicating that the original accelerated electron energy spectrum is much harder than commonly thought, with power-law index around 1.5 instead of the canonical 2.5. The radio spectra peak at high frequencies and exhibit a variety of shapes. For a small set of low-z sources, we find a spectral upturn at high frequencies, indicating the presence of intrinsic cold dust. Variability can generally be approximated by achromatic variations, while sources with clear signatures of evolving shocks appear to be limited to the strongest outbursts.
843. K-band images of star-forming regions
ID:
ivo://CDS.VizieR/J/other/PASA/26.439
Title:
K-band images of star-forming regions
Short Name:
J/other/PASA/26.
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present deep, wide-field, Ks-band (2.14-micron) images towards 87 southern massive star formation regions traced by methanol maser emission. Using point-spread function fitting, we generate 2.14-micron point source catalogues (PSCs) towards each of the regions. For the regions between 10{deg}<l<350{deg} and |b|<1, we match the 2.14-micron sources with the GLIMPSE point source catalogue to generate a combined 2.14- to 8.0-micron point source catalogue. We provide this data for the astronomical community to utilise in studies of the stellar content of embedded clusters.
844. KCAL VERA 22 GHz calibrator survey
ID:
ivo://CDS.VizieR/J/AJ/143/35
Title:
KCAL VERA 22 GHz calibrator survey
Short Name:
J/AJ/143/35
Date:
21 Oct 2021
Publisher:
CDS
Description:
We observed at 22GHz with the VLBI array VERA a sample of 1536 sources with correlated flux densities brighter than 200mJy at 8GHz. One half of target sources has been detected. The detection limit was around 200mJy. We derived the correlated flux densities of 877 detected sources in three ranges of projected baseline lengths. The objective of these observations was to determine the suitability of given sources as phase calibrators for dual-beam and phase-referencing observations at high frequencies. Preliminary results indicate that the number of compact extragalactic sources at 22GHz brighter than a given correlated flux density level is twice less than at 8GHz.
845. Kepler K2 mission fields 3-5: radio continuum survey
ID:
ivo://CDS.VizieR/J/AJ/158/31
Title:
Kepler K2 mission fields 3-5: radio continuum survey
Short Name:
J/AJ/158/31
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present Murchison Widefield Array (MWA) monitoring of the Kepler K2 mission fields 3, 4, and 5 at frequencies of 155 and 186 MHz, from observations contemporaneous with the K2 observations. This work follows from previous MWA and Giant Metrewave Radio Telescope (GMRT) surveys of field 1, with the current work benefiting from a range of improvements in the data processing and analysis. We continue to build a body of systematic low-frequency blind surveys overlapping with transient/variable survey fields at other wavelengths, providing multiwavelength data for object classes such as flare stars. From the current work, we detect no variable objects at a surface density above 2x10^-4^ per square degree, at flux densities of ~500 mJy, and an observation cadence of days to weeks, representing almost an order of magnitude decrease in the measured upper limits compared to previous results in this part of observational parameter space. This continues to show that radio transients at meter and centimeter wavelengths are rare.
846. KEYSTONE: ammonia structures in Galactic GMCs
ID:
ivo://CDS.VizieR/J/ApJ/884/4
Title:
KEYSTONE: ammonia structures in Galactic GMCs
Short Name:
J/ApJ/884/4
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present initial results from the K-band Focal Plane Array Examinations of Young STellar Object Natal Environments survey (KEYSTONE), a large project on the 100m Green Bank Telescope mapping ammonia emission across 11 giant molecular clouds at distances of 0.9-3.0kpc (Cygnus X North, Cygnus X South, M16, M17, Mon R1, Mon R2, NGC 2264, NGC 7538, Rosette, W3, and W48). This data release includes the NH_3_ (1,1) and (2,2) maps for each cloud, which are modeled to produce maps of kinetic temperature, centroid velocity, velocity dispersion, and ammonia column density. Median cloud kinetic temperatures range from 11.4+/-2.2K in the coldest cloud (Mon R1) to 23.0+/-6.5K in the warmest cloud (M17). Using dendrograms on the NH_3_ (1,1) integrated intensity maps, we identify 856 dense gas clumps across the 11 clouds. Depending on the cloud observed, 40%-100% of the clumps are aligned spatially with filaments identified in H2 column density maps derived from spectral energy distribution fitting of dust continuum emission. A virial analysis reveals that 523 of the 835 clumps (~63%) with mass estimates are bound by gravity alone. We find no significant difference between the virial parameter distributions for clumps aligned with the dust-continuum filaments and those unaligned with filaments. In some clouds, however, hubs or ridges of dense gas with unusually high mass and low virial parameters are located within a single filament or at the intersection of multiple filaments. These hubs and ridges tend to host water maser emission, multiple 70{mu}m detected protostars, and have masses and radii above an empirical threshold for forming massive stars.
847. KGS EoR0 Catalogue
ID:
ivo://CDS.VizieR/J/MNRAS/461/4151
Title:
KGS EoR0 Catalogue
Short Name:
J/MNRAS/461/4151
Date:
21 Oct 2021
Publisher:
CDS
Description:
Detection of the epoch of reionization HI signal requires a precise understanding of the intervening galaxies and AGN, both for instrumental calibration and foreground removal. We present a catalogue of 7394 extragalactic sources at 182MHz detected in the RA=0 field of the Murchison Widefield Array Epoch of Reionization observation programme. Motivated by unprecedented requirements for precision and reliability we develop new methods for source finding and selection. We apply machine learning methods to self-consistently classify the relative reliability of 9490 source candidates. A subset of 7466 are selected based on reliability class and signal-to-noise ratio criteria. These are statistically cross-matched to four other radio surveys using both position and flux density information. We find 7369 sources to have confident matches, including 90 partially resolved sources that split into a total of 192 sub-components. An additional 25 unmatched sources are included as new radio detections. The catalogue sources have a median spectral index of -0.85. Spectral flattening is seen towards lower frequencies with a median of -0.71 predicted at 182MHz. The astrometric error is 7-arcsec compared to a 2.3-arcmin beam FWHM. The resulting catalogue covers ~1400deg^2^ and is complete to approximately 80mJy within half beam power. This provides the most reliable discrete source sky model available to date in the MWA EoR0 field for precision foreground subtraction.
848. Kinematical models for double radio sources
ID:
ivo://CDS.VizieR/J/A+AS/132/31
Title:
Kinematical models for double radio sources
Short Name:
J/A+AS/132/31
Date:
21 Oct 2021
Publisher:
CDS
Description:
These tables contain structural parameters for a large sample of classical FR II (Fanaroff-Riley II, 1974MNRAS.167p..31F) double radio sources obtained from the literature.
849. Kinematic distance ambiguity in HII regions
ID:
ivo://CDS.VizieR/J/ApJ/753/62
Title:
Kinematic distance ambiguity in HII regions
Short Name:
J/ApJ/753/62
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using H I absorption spectra from the International Galactic Plane Survey, a new method is implemented to resolve the kinematic distance ambiguity for 75 H II regions with known systemic velocities from radio recombination lines. A further 40 kinematic distance determinations are made for H II region candidates without known systemic velocities through an investigation of the presence of H I absorption around the terminal velocity. New kinematic distance determinations can be used to further constrain spiral arm parameters and the location and extent of other structures in the Milky Way disk. H I absorption toward continuum sources beyond the solar circle is also investigated. Follow-up studies of H I at higher resolution than the 1' to 2' of existing Galactic Plane Surveys will provide kinematic distances to many more H II regions on the far side of the Galactic center. On the basis of the velocity channel summation technique developed in this paper, a much larger sample of H II regions will be analyzed in a future paper to remove the near-far distance ambiguity.
850. Kinematic distances to GRS molecular clouds
ID:
ivo://CDS.VizieR/J/ApJ/699/1153
Title:
Kinematic distances to GRS molecular clouds
Short Name:
J/ApJ/699/1153
Date:
21 Oct 2021
Publisher:
CDS
Description:
Kinematic distances to 750 molecular clouds identified in the ^13^COJ=1-0 Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey (GRS) are derived assuming the Clemens rotation curve of the Galaxy. The kinematic distance ambiguity is resolved by examining the presence of HI self-absorption toward the ^13^CO emission peak of each cloud using the Very Large Array Galactic Plane Survey. We also identify 21cm continuum sources embedded in the GRS clouds in order to use absorption features in the HI 21cm continuum to distinguish between near and far kinematic distances. The Galactic distribution of GRS clouds is consistent with a four-arm model of the Milky Way. The locations of the Scutum-Crux and Perseus arms traced by GRS clouds match star-count data from the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire star-count data. We conclude that molecular clouds must form in spiral arms and be short-lived (lifetimes <10^7^yr) in order to explain the absence of massive, ^13^CO bright molecular clouds in the interarm space.