- ID:
- ivo://CDS.VizieR/J/MNRAS/502/4779
- Title:
- 28-40GHz variability and polarimetry
- Short Name:
- J/MNRAS/502/4779
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We observed 51 sources in the Q-U-I JOint TEnerife (QUIJOTE) cosmological fields which were brighter than 1Jy at 30GHz in the Planck Point Source Catalogue (version 1), with the Very Large Array at 28-40GHz, in order to characterise their high-radio-frequency variability and polarization properties. We find a roughly log-normal distribution of polarization fractions with a median of 2%, in agreement with previous studies, and a median rotation measure (RM) of ~1110rad/m^2^ with one outlier up to ~64000rad/m^2^ which is among the highest RMs measured in quasar cores. We find hints of a correlation between the total intensity flux density and median polarization fraction. We find 59% of sources are variable in total intensity, and 100% in polarization at 3{sigma} level, with no apparent correlation between total intensity variability and polarization variability. This indicates that it will be difficult to model these sources without simultaneous polarimetric monitoring observations and they will need to be masked for cosmological analysis.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/438/3058
- Title:
- 15GHz variability of {gamma}-ray blazars
- Short Name:
- J/MNRAS/438/3058
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from four years of twice-weekly 15GHz radio monitoring of about 1500 blazars with the Owens Valley Radio Observatory 40m telescope. Using the intrinsic modulation index to measure variability amplitude, we find that, with >6{sigma} significance, the radio variability of radio-selected {gamma}-ray-loud blazars is stronger than that of {gamma}-ray-quiet blazars. Our extended data set also includes at least 21 months of data for all AGN with 'clean' associations in the Fermi Large Area Telescope First AGN Catalog, 1LAC. With these additional data, we examine the radio variability properties of a {gamma}-ray-selected blazar sample. Within this sample, we find no evidence for a connection between radio variability amplitude and optical classification. In contrast, for our radio-selected sample we find that the BL Lac object subpopulation is more variable than the flat-spectrum radio quasar (FSRQ) subpopulation. Radio variability is found to correlate with the synchrotron peak frequency, with low- and intermediate-synchrotron-peaked blazars varying more than high-synchrotron-peaked ones. We find evidence for a significant negative correlation between redshift and radio variability among bright FSRQs.
- ID:
- ivo://CDS.VizieR/J/AJ/128/1570
- Title:
- 8.4GHz VLBA observations of scintillating sources
- Short Name:
- J/AJ/128/1570
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 8.4GHz Very Long Baseline Array (VLBA) observations of 75 extragalactic radio sources drawn from the scintillating sources discovered in the Microarcsecond Scintillation-induced Variability survey.
- ID:
- ivo://CDS.VizieR/J/A+A/364/391
- Title:
- 86GHz VLBI survey of compact radio sources
- Short Name:
- J/A+A/364/391
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- File table1 contains the list of observed sources, providing the source coordinates (J2000) and redshift, detection status, type, optical magnitude, and brightness temperature of the radio emission. File table4 contains the description of the VLBI data, and provide the observed total and correlated flux densities, the parameters of single gaussian component model fits, and the parameters of hybrid images of the observed sources. File table5 contains multicomponent model fits for the sources with detected extended structures and the brightness temperatures derived from these model fits.
- ID:
- ivo://CDS.VizieR/J/AZh/62/229
- Title:
- Giant H II region Ratan-600 observations
- Short Name:
- J/AZh/62/229
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of observations of a giant H II region, situated at the longitudes 4-10deg, at the wavelength 7.6cm are presented. A catalogue has been compiled containing 63 sources for which the positions, flux densities, and angular dimensions have been determined. Forty-four objects with the fluxes P<1Jy and having small angular sizes have been detected. The radio brightness distribution of the background component of the galactic radio emission has been obtained. A weak background extended by more than 2deg in the galactic latitude has been registered. It is shown that the detected weak objects represent a more high-latitude population than the strong galactic sources and are probably associated with the weak extended background.
- ID:
- ivo://CDS.VizieR/J/other/Galax/9.99
- Title:
- Giant Radio Galaxies in RACS
- Short Name:
- J/other/Galax/9.
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We report the results of a visual inspection of images of the Rapid ASKAP Continuum Survey (RACS) in search of extended radio galaxies (ERG) that reach or exceed linear sizes on the order of one Megaparsec. We searched a contiguous area of 1059deg^2^ from RA=20h20m to 06h20m, and -50{deg}<Dec<-40{deg} which is covered by deep multi-band optical images of the Dark Energy Survey (DES), and in which previously only three ERGs larger than 1Mpc had been reported. For over 1800 radio galaxy candidates inspected, our search in optical and infrared images resulted in hosts for 1440 ERG, for which spectroscopic and photometric redshifts from various references were used to convert their largest angular size (LAS) to projected linear size (LLS). This resulted in 178 newly discovered giant radio sources (GRS) with LLS>1Mpc, of which 18 exceed 2Mpc and the largest one is 3.4Mpc. Their redshifts range from 0.02 to about 2.0, but only 10 of the 178 new GRS have spectroscopic redshifts. For the 146 host galaxies the median r-band magnitude and redshift are 20.9 and 0.64, while for the 32 quasars or candidates these are 19.7 and 0.75. Merging the six most recent large compilations of GRS results in 458 GRS larger than 1Mpc, so we were able to increase this number by about 39 per cent to now 636.
- ID:
- ivo://CDS.VizieR/J/ApJS/253/25
- Title:
- Giant radio quasars from SDSS, FIRST & NVSS
- Short Name:
- J/ApJS/253/25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the largest sample of giant radio quasars (GRQs), which are defined as having a projected linear size greater than 0.7Mpc. The sample consists of 272 GRQs, of which 174 are new objects discovered through cross-matching the NRAO Very Large Array Sky Survey and the Sloan Digital Sky Survey 14th Data Release Quasar Catalog (DR14Q) and confirmed using Faint Images of the Radio Sky at Twenty-Centimeters (FIRST) radio maps. In our analysis we compare the GRQs with 367 smaller, lobe-dominated radio quasars found using our search method, as well as with quasars from the SDSS DR14Q, investigating the parameters characterizing their radio emission (i.e., total and core radio luminosity, radio core prominence), optical properties (black hole masses, accretion rates, distribution in Eigenvector 1 plane) and infrared colors. For the GRQs and smaller radio quasars we find a strong correlation between [OIII] luminosity and radio luminosity at 1.4GHz, indicating a strong connection between radio emission and conditions in the narrow-line region. We spot no significant differences between GRQs and smaller radio quasars, however we show that most extended radio quasars belong to a quasar population of evolved active galactic nuclei with large black hole masses and low accretion rates. We also show that GRQs have bluer W2-W3 colors compared to SDSS quasars with FIRST detections, indicating differences in the structure of the dusty torus.
- ID:
- ivo://CDS.VizieR/VIII/102
- Title:
- GLEAM II. Galactic plane
- Short Name:
- VIII/102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This work makes available a further of the GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey, covering half of the accessible galactic plane, across 20 frequency bands sampling 72-231MHz, with resolution 4-2arcmin. Unlike previous GLEAM data releases, we used multi-scale CLEAN to better deconvolve large-scale galactic structure. For the galactic longitude ranges 345{deg}<l<67{deg}, 180{deg}<l<240{deg}, we provide a compact source catalogue of 22037 components selected from a 60-MHz bandwidth image centred at 200MHz, with RMS noise ~-10-20mJy/beam and position accuracy better than 2-arcsec. The catalogue has a completeness of 50% at ~120mJy, and a reliability of 99.86%. It covers galactic latitudes 1{deg}<=|b|<=10{deg} towards the galactic centre and |b|<=10{deg} for other regions, and is available from Vizier; images covering |b|<=10{deg} for all longitudes are made available on the GLEAM Virtual Observatory (VO).server and SkyView.
- ID:
- ivo://CDS.VizieR/VIII/109
- Title:
- GLEAM III. South Galactic Pole
- Short Name:
- VIII/109
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the South Galactic Pole (SGP) data release from the GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey. These data combine both years of GLEAM observations at 72-231MHz conducted with the Murchison Widefield Array (MWA) and cover an area of 5,113 deg^2^ centred on the SGP at 20h40m<RA<05h04m and -48{deg}<Dec<-2{deg}. At 216MHz, the typical rms noise is ~5mJy/beam and the angular resolution ~2 arcmin. The source catalogue contains a total of 108851 components above 5{sigma}, of which 77 per cent have measured spectral indices between 72 and 231MHz. Improvements to the data reduction in this release include the use of the GLEAM Extragalactic catalogue as a sky model to calibrate the data, a more efficient and automated algorithm to deconvolve the snapshot images, and a more accurate primary beam model to correct the flux scale. This data release enables more sensitive large-scale studies of extragalactic source populations as well as spectral variability studies on a one-year timescale.
- ID:
- ivo://CDS.VizieR/J/other/PASA/38.41
- Title:
- GLEAM 200MHz local radio luminosity function
- Short Name:
- J/other/PASA/38.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) is a radio continuum survey at 76-227MHz of the entire southern sky (Declination <+30{deg}) with an angular resolution of ~2arcmin. In this paper, we combine GLEAM data with optical spectroscopy from the 6dF Galaxy Survey to construct a sample of 1,590 local (median z~0.064) radio sources with S_200MHz_>55mJy across an area of ~16700deg^2^. From the optical spectra, we identify the dominant physical process responsible for the radio emission from each galaxy: 73 per cent are fuelled by an active galactic nucleus (AGN) and 27 per cent by star formation. We present the local radio luminosity function for AGN and star-forming galaxies at 200MHz and characterise the typical radio spectra of these two populations between 76MHz and ~1GHz. For the AGN, the median spectral index between 200MHz and ~1GHz, {alpha}, is -0.600+/-0.010 (where S proportional to {nu}^{alpha}^) and the median spectral index within the GLEAM band, {alpha}_low_, is -0.704+/-0.011. For the star-forming galaxies, the median value of {alpha}_high_ is -0.650+/-0.010 and the median value of {alpha}_low_ is -0.596+/-0.015. Among the AGN population, flat-spectrum sources are more common at lower radio luminosity, suggesting the existence of a significant population of weak radio AGN that remain core-dominated even at low frequencies. However, around 4 per cent of local radio AGN have ultra-steep radio spectra at low frequencies ({alpha}_low_<-1.2). These ultra-steep-spectrum sources span a wide range in radio luminosity, and further work is needed to clarify their nature.
