We present a sample of 74 radio sources with recurrent jet activity. The sample consists of 67 galaxies, 2 quasars and 5 unidentified sources, selected from the published data or are newly recognized. The sample's redshift range is 0.002<z<0.7 and the size of inner and outer structures varies from 0.02 to 4248kpc. We analyse the optical and radio properties of the sample and compare them with the characteristics of ordinary one-off FRII radio sources. With the help of stellar population modelling, we derive black hole masses and stellar masses of host galaxies of 35 restarting radio sources, finding that the black hole masses in restarting radio sources are comparable to those of typical single-cycle FRII radio sources. The obtained median values of log M_BH_ are 8.58 and 8.62M_{sun}_. Unlike the black hole masses, the stellar masses in restarting radio sources tend to be smaller than in the FRII sources. Although the stellar populations of the hosts of recurrent activity sources are dominated by old stars, a significant fraction of young stars can be observed as well. Based on the Sloan Digital Sky Survey photometric observations, we also analyse the morphology of the host galaxies and obtained significantly smaller concentration indices for the restarting radio sources when compared to the classical FRII hosts. This effect can be interpreted as a result of frequent merger events in the history of host galaxies of restarting radio sources.
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.
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.
Faint radio sources in GOODS-N and -S. I. VLA 5GHz
Short Name:
J/ApJ/875/80
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the first results from the deep and wide 5GHz radio observations of the Great Observatories Origins Deep Survey (GOODS)-North ({sigma}=3.5{mu}Jy/beam, synthesized beam size {theta}=1.47"x1.42", and 52 sources over 109arcmin^2^) and GOODS-South ({sigma}=3.0{mu}Jy/beam, {theta}=0.98"x0.45", and 88 sources over 190arcmin^2^) fields using the Karl G. Jansky Very Large Array. We derive radio spectral indices {alpha} between 1.4 and 5GHz using the beam-matched images and show that the overall spectral index distribution is broad even when the measured noise and flux bias are considered. We also find a clustering of faint radio sources around {alpha}=0.8, but only within S_5GHz_<150{mu}Jy. We demonstrate that the correct radio spectral index is important for deriving accurate rest-frame radio power and analyzing the radio-FIR correlation, and adopting a single value of {alpha}=0.8 leads to a significant scatter and a strong bias in the analysis of the radio-FIR correlation, resulting from the broad and asymmetric spectral index distribution. When characterized by specific star formation rates, the starburst population (58%) dominates the 5GHz radio source population, and the quiescent galaxy population (30%) follows a distinct trend in spectral index distribution and the radio-FIR correlation. Lastly, we offer suggestions on sensitivity and angular resolution for future ultra-deep surveys designed to trace the cosmic history of star formation and AGN activity using radio continuum as a probe.
