Long term monitoring results from 2001 to mid 2004 of quasar observations at 22 and 37GHz done at the Metsahovi radio observatory are presented. Approximately 10000 observations are published here.
Long term monitoring results from mid 1995 to the end of 2000 of quasar observations at 22, 37 and 87GHz done at the Metsahovi radio observatory are presented. Approximately 15700 observations are published here.
One hundred and four radio sources from the 3C and 4C catalogues have been mapped with a resolution of 2arcsec in RA and 2cosec{delta}arcsec in DE. The results are presented here as contour maps and in tabular form, with accurate measurements of the positions of optical objects in the fields.
We report on the detection of optically thick free-free radio sources in the galaxies M33, NGC 253, and NGC 6946 using data in the literature. We interpret these sources as being young embedded star birth regions that are likely to be clusters of ultracompact H II regions. All 35 of the sources presented in this article have positive radio spectral indices ({alpha}>0 for S_{nu}_){prop.to}{nu}^{alpha}^), suggesting an optically thick thermal bremsstrahlung origin from the H II region surrounding the hot stars.
Over 13500 continuum observations of extragalactic sources are presented. These observations of 157 sources at 22, 37 and 87GHz more than doubles the millimeter observations of these sources. The data are between 1990.5 and 1995.5, and combined with our earlier published data form a 15 year database.
The rotation measures of 555 extragalactic radio sources are calculated as a result of a large number of new linear polarization measurements carried out by us at several wavelengths between 1.59 and 10.5GHz. A summary of references for previous polarization measurements is included, and the procedure for optimizing the number of unambiguous rotation measures is described.
We carried out VLA observations in A configuration at 74-MHz of a new sample of faint Compact Steep-Spectrum (CSS) radio sources as part of a comprehensive project to study the nature and evolution of peaked-spectrum radio sources. In conjunction with higher frequency spectral information this has enabled us to determine the peak frequency and peak flux density of the spectral turnover for 35 faint CSS radio sources. Spectra are presented. An analysis is given of the quality of the images and their suitability for integrated intensity measurements of the CSS radio sources.
A sample of 123 radio sources that exhibit significant variations at 1.4GHz on a 7 year baseline has been created using FIRST VLA B-configuration data from 1995 and 2002 on a strip at {delta}=0 near the south Galactic cap. This sample spans the range of radio flux densities from ~2 to 1000mJy. It presents both in size and radio flux density range a unique starting point for variability studies of galaxies and quasars harboring lower luminosity active galactic nuclei (AGNs).
We have used the Australia Telescope Compact Array (ATCA) to search for faint radio sources in a ~3deg^2^ region of sky covered by the 2dF Galaxy Redshift Survey (2dFGRS, Cat. <VII/226>). Over the region surveyed, the 1{sigma} noise level at 1.4GHz ranges from 20Jy to 1mJy. The survey region includes 365 2dFGRS galaxies, of which 316 have good-quality spectra (176 early-type galaxies or active galactic nuclei, and 140 star-forming galaxies). The fraction of 2dFGRS galaxies detected as radio sources in our survey rises from ~4% at a 3{sigma} detection limit of 0.3mJy to 12% at 75{mu}Jy, with roughly equal numbers of star-forming galaxies and active galactic nuclei (AGNs) being detected.
A complete, flux density limited sample of 96 faint (>0.5mJy) radio sources is selected from the 10C survey at 15.7GHz in the Lockman Hole. We have matched this sample to a range of multi-wavelength catalogues, including Spitzer Extragalactic Representative Volume Survey, Spitzer Wide-area Infrared Extragalactic survey, United Kingdom Infrared Telescope Infrared Deep Sky Survey and optical data; multi-wavelength counterparts are found for 80 of the 96 sources and spectroscopic redshifts are available for 24 sources. Photometric redshifts are estimated for the sources with multi-wavelength data available; the median redshift of the sample is 0.91 with an interquartile range of 0.84. Radio-to-optical ratios show that at least 94 per cent of the sample are radio loud, indicating that the 10C sample is dominated by radio galaxies. This is in contrast to samples selected at lower frequencies, where radio-quiet AGN and star-forming galaxies are present in significant numbers at these flux density levels. All six radio-quiet sources have rising radio spectra, suggesting that they are dominated by AGN emission. These results confirm the conclusions of that the faint, flat-spectrum sources which are found to dominate the 10C sample below ~1mJy are the cores of radio galaxies. The properties of the 10C sample are compared to the Square Kilometre Array Design Studies Simulated Skies; a population of low-redshift star-forming galaxies predicted by the simulation is not found in the observed sample.