- ID:
- ivo://CDS.VizieR/J/MNRAS/430/1961
- Title:
- 93.2GHz observations of 9C sources
- Short Name:
- J/MNRAS/430/1961
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from follow-up observations of a sample of 80 radio sources, originally detected as part of the 15.2-GHz Ninth Cambridge (9C) survey. The observations were carried out, close to simultaneously, at two frequencies: 15.7GHz, using the Arcminute Microkelvin Imager (AMI) Large Array, and 93.2GHz, using the Combined Array for Research in Millimeter-wave Astronomy (CARMA). There is currently little direct information on the 90-GHz-band source count for S<~1Jy. However, we have used the measured 15.7-to-93.2-GHz spectral-index distribution and 9C source count to predict the differential source count at 93.2GHz as 26+/-4(S/Jy)^-2.15^Jy^-1^sr^-1^; our projection is estimated to be most accurate for 10<~S<~100mJy. Our estimated differential count is more than twice the 90-GHz prediction made by Waldram et al. (2007, Cat. J/MNRAS/379/1442); we believe that this discrepancy is because the measured 43-GHz flux densities used in making their prediction were too low. Similarly, our prediction is significantly higher than that of Sadler et al. (2008, Cat. J/MNRAS/385/1656) at 95GHz. Since our spectral-index distribution is similar to the 20-to-95-GHz distribution measured by Sadler et al. and used in making their prediction, we believe that the difference is almost entirely attributable to the dissimilarity in the lower frequency counts used in making the estimates.
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- ID:
- ivo://CDS.VizieR/J/AJ/142/3
- Title:
- 1.4GHz observations of Stripe 82
- Short Name:
- J/AJ/142/3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a high-resolution radio survey of the Sloan Digital Sky Survey (SDSS) Southern Equatorial Stripe, a.k.a. Stripe 82. This 1.4GHz survey was conducted with the Very Large Array primarily in the A-configuration, with supplemental B-configuration data to increase sensitivity to extended structure. The survey has an angular resolution of 1.8" and achieves a median rms noise of 52{mu}Jy/beam over 92deg^2^. This is the deepest 1.4GHz survey to achieve this large of an area, filling a gap in the phase space between small, deep and large, shallow surveys. It also serves as a pilot project for a larger high-resolution survey with the Expanded Very Large Array. We discuss the technical design of the survey and details of the observations, and we outline our method for data reduction. We present a catalog of 17969 isolated radio components, for an overall source density of ~195sources/deg^2^. The astrometric accuracy of the data is excellent, with an internal check utilizing multiply observed sources yielding an rms scatter of 0.19" in both right ascension and declination. A comparison to the SDSS-DR7 Quasar Catalog further confirms that the astrometry is well tied to the optical reference frame, with mean offsets of 0.02+/-0.01" in right ascension, and 0.01+/-0.02" in declination. A check of our photometry reveals a small, negative CLEAN-like bias on the level of 35{mu}Jy. We report on the catalog completeness, finding that 97% of FIRST-detected quasars are recovered in the new Stripe 82 radio catalog, while faint, extended sources are more likely to be resolved out by the resolution bias. We conclude with a discussion of the optical counterparts to the catalog sources, including 76 newly detected radio quasars.
- ID:
- ivo://CDS.VizieR/J/ApJ/614/607
- Title:
- 8.4GHz obs. of scintillating sources
- Short Name:
- J/ApJ/614/607
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We compare the milliarcsecond-scale morphology of scintillating and nonscintillating sources. The scintillating sources are drawn from those flat-spectrum extragalactic radio sources discovered, by the Micro-Arcsecond Scintillation-Induced Variability Survey (MASIV, Lovell et al, 2003AJ....126.1699L), to have flux density variability at 5GHz on timescales from hours to days. Intrinsic source structure information is obtained from previously published and/or publicly available 8.4GHz Very Long Baseline Array images. A sample of low flux density (S_{nu}=5GHz_<0.3Jy) scintillating sources was compared with a sample of high flux density (S_{nu}=5GHz_~1Jy) scintillators, as well as a sample of high flux density nonscintillators.
- ID:
- ivo://CDS.VizieR/J/A+A/482/483
- Title:
- GHz-peaked spectrum (GPS) sources
- Short Name:
- J/A+A/482/483
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Gigahertz-peaked spectrum (GPS) sources and high frequency peakers (HFPs) are among the smallest of active galactic nuclei currently believed to represent the earliest phases in the evolution of extragalactic radio sources. Recently there has been evidence of contamination by other types of radio sources among the GPS and HFP samples, but the confirmed GPS sources or HFPs also seem to form a very heterogeneous population. We study the statistical clustering of the GPS sources and the HFPs by taking as many source parameters as possible to find homogeneous groups among the sources. We expect the clustering to give us insight into the physical parameters that play a role in different source populations. We have collected a sample of 206 GPS sources and HFPs from the literature and gathered a massive database of various source properties, such as the redshift, the size, the polarization, the magnitudes, and the properties of the radio continuum. To visualize and to cluster these multidimensional data we used self-organising maps (SOM), which are neural networks trained by an unsupervised algorithm. We have classified the sources with an auxiliary classification to trace the locations of different types of radio continuum spectra on the map.
- ID:
- ivo://CDS.VizieR/J/A+AS/131/303
- Title:
- GHz-Peaked-Spectrum radio sources
- Short Name:
- J/A+AS/131/303
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We define a complete sample of thirty-three GHz-Peaked-Spectrum (GPS) radio sources based on their spectral properties. We present measurements of the radio spectra and polarization of the complete sample and a list of additional GPS sources which fail one or more criteria to be included in the complete sample. The majority of the data have been obtained from quasi-simultaneous multi-frequency observations at the Very Large Array (VLA) during 3 observing sessions. Low frequency data from the Westerbork Synthesis Radio Telescope (WSRT) and from the literature have been combined with the VLA data in order to better define the spectral shape. The objects presented here show a rather wide range of spectral indices at high and low frequencies, including a few cases where the spectral index below the turnover is close to the theoretical value of 2.5 typical of self-absorbed incoherent synchrotron emission. Faint and diffuse extended emission is found in about 10% of the sources. In the majority of the GPS sources, the fractional polarization is found to be very low, consistent with the residual instrumental polarization of 0.3%.
- ID:
- ivo://CDS.VizieR/J/MNRAS/380/1449
- Title:
- 1.4GHz radio sources in Lynx and Hercules fields
- Short Name:
- J/MNRAS/380/1449
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- With the goal of identifying high-redshift radio galaxies with Fanaroff-Riley class I (FR I) classification, here are presented high-resolution, wide-field radio observations, near-infrared and optical imaging and multi-object spectroscopy of two fields of the Leiden-Berkeley Deep Survey. These fields, Hercules.1 and Lynx.2, contain a complete sample of 81 radio sources with S(1.4GHz)>0.5mJy within 0.6deg^2^. This sample will form the basis for a study of the population and cosmic evolution of high-redshift, low-power, FR I radio sources which will be presented in Paper II. Currently, the host galaxy identification fraction is 86 per cent with 11 sources remaining unidentified at a level of r'>=25.2mag (Hercules; 4 sources) or r'>=24.4mag (Lynx; 7 sources) or K>=20mag. Spectroscopic redshifts have been determined for 49 per cent of the sample and photometric redshift estimates are presented for the remainder of the sample.
- ID:
- ivo://CDS.VizieR/J/ApJ/716/521
- Title:
- 31GHz sky survey with the SZA
- Short Name:
- J/ApJ/716/521
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first sample of 31GHz selected sources to flux levels of 1mJy. From late 2005 to mid-2007, the Sunyaev-Zel'dovich Array observed 7.7deg^2^ of the sky at 31GHz to a median rms of 0.18mJy/beam. We identify 209 sources at greater than 5{sigma} significance in the 31GHz maps, ranging in flux from 0.7mJy to ~200mJy. Archival NVSS data at 1.4GHz and observations at 5GHz with the Very Large Array are used to characterize the sources. We determine the maximum-likelihood integrated source count to be N(>S)=(27.2+/-2.5)deg^-2^x(S_mJy_)^-1.18+/-0.12^ over the flux range 0.7-15mJy. This result is significantly higher than predictions based on 1.4GHz selected samples, a discrepancy which can be explained by a small shift in the spectral index distribution for faint 1.4GHz sources. From comparison with previous measurements of sources within the central arcminute of massive clusters, we derive an overdensity of 6.8+/-4.4, relative to field sources.
- ID:
- ivo://CDS.VizieR/J/AJ/99/1071
- Title:
- 1.4 GHz source survey
- Short Name:
- J/AJ/99/1071
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on 1.4GHz continuum observations for 56 contiguous VLA fields, using the D configuration, in a region devoid of nearby, rich galaxy clusters (at z<0.4). 354 continuum sources are tabulated, with fluxes down to about 1.5mJy, in an area of about 12degres^+2^. Only about seven of the 354 radio sources are associated with known rich galaxy clusters at z>0.4 (tabulated by Gunn, Hoessel, and Oke, 1986ApJ...306...30G). We compare source positions with those from an optical catalog (generated from a POSS plate with the use of the Minnesota Automated Plate Scanner) and find mild correlations on angular scales of order 1arcmin. This suggests some association of radio sources with galaxy groups (sizes of order 200 kpc) at redshifts of order z~0.1, even though there are no rich galaxy clusters in this redshift range.
- ID:
- ivo://CDS.VizieR/J/A+AS/139/545
- Title:
- 1-22 GHz spectra survey
- Short Name:
- J/A+AS/139/545
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present observational results for extragalactic radio sources with milliarcsecond components, obtained with the 600 meter ring radio telescope RATAN-600 from 1st to 22nd December, 1997. For each source, a six frequency broad band radio spectrum was obtained by observing simultaneously with an accuracy up to a minute at 1.4, 2.7, 3.9, 7.7, 13 and 31 cm. The observed list is selected from Preston et al. (1985AJ.....90.1599P) VLBI survey and contains all the sources in the declinations between -30 and +43 degrees with a correlated flux density exceeding 0.1 Jy at 13 cm. The sample includes the majority of sources to be studied in the current VSOP survey and the future RadioAstron Space VLBI mission.
- ID:
- ivo://CDS.VizieR/J/A+AS/41/421
- Title:
- 1.4GHz survey in the Virgo region
- Short Name:
- J/A+AS/41/421
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Radio continuum observations made with the Westerbork Synthesis Radio Telescope at 1.4GHz are presented for 274 galaxies in the Virgo Cluster region. The observations are partly full syntheses and partly east-west strip distributions. For the 55 detected galaxies the emission is separated into central and extended components. A brief summary of the analysis is also given.
