- ID:
- ivo://CDS.VizieR/J/MNRAS/385/1656
- Title:
- Extragalactic radio-sources at 95GHz
- Short Name:
- J/MNRAS/385/1656
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used the Australia Telescope Compact Array (ATCA) at 95GHz to carry out continuum observations of 130 extragalactic radio sources selected from the Australia Telescope 20GHz (AT20G) survey. We use a triple-correlation method to measure simultaneous 20- and 95-GHz flux densities for these objects, and over 90 per cent of our target sources are detected at 95GHz. We demonstrate that the ATCA can robustly measure 95-GHz flux densities with an accuracy of ~10 per cent in a few minutes for sources stronger than about 50mJy. We measure the distribution of radio spectral indices in a flux-limited sample of extragalactic sources, and show that the median 20-95GHz spectral index does not vary significantly with flux density for S_20_>150mJy . This finding allows us to estimate the extragalactic radio source counts at 95GHz by combining our observed 20-95GHz spectral-index distribution with the accurate 20-GHz source counts measured in the AT20G survey.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+AS/120/201
- Title:
- Extragalactic radio sources optical positions
- Short Name:
- J/A+AS/120/201
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Based on 28 individual catalogues, in which the positions of optical counterparts of extragalactic radio sources are listed, we compiled a combined catalogue by means of a weighted least squares adjustment. The catalogue is in the system of FK5/J2000.0. It consists of about five hundred sources, among which there are 56 primary sources with position uncertainties as 0.09". Comparisons show that the orientation differences between optical and radio frames are A1=-0.013"+/-0.012", A2=0.077"+/-0.012", A3=0.005"+/-0.009". Local relative deformations are not obvious within the precision of ground-based optical observations.
- ID:
- ivo://CDS.VizieR/J/A+AS/135/571
- Title:
- Extragalactic radio sources polarization
- Short Name:
- J/A+AS/135/571
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present linear polarization measurements of 154 extragalactic radio sources at {lambda}6.3cm, as part of a continuing effort to expand and improve our Faraday rotation determinations of radio galaxies and quasars. The excellent telescope optics of the Effelsberg 100 m telescope at this wavelength, combined with a matrix method we applied for calibrating out all components of the instrumental polarization enables us to achieve better than average accuracy in the determinations of linear polarization degree and position angle. In the absence of thermal noise errors, these are repeatable to better than 0.2% and 0.1{deg} respectively, for the prime calibrator, 3C 286.
- ID:
- ivo://CDS.VizieR/J/A+A/440/409
- Title:
- Extragalactic sources at 22 and 37GHz
- Short Name:
- J/A+A/440/409
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 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.
- ID:
- ivo://CDS.VizieR/J/A+A/427/769
- Title:
- Extragalactic sources at 22, 37 and 87GHz
- Short Name:
- J/A+A/427/769
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 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.
- ID:
- ivo://CDS.VizieR/J/A+AS/132/305
- Title:
- Extragal. radio sources at 22, 37 and 87GHz
- Short Name:
- J/A+AS/132/305
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 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.
- ID:
- ivo://CDS.VizieR/J/AJ/127/2565
- Title:
- Faint FIRST variable radio sources
- Short Name:
- J/AJ/127/2565
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 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).
- ID:
- ivo://CDS.VizieR/J/AJ/130/923
- Title:
- Faint radio sources in the NOAO Bootes field
- Short Name:
- J/AJ/130/923
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As a step toward investigating the parsec-scale properties of faint extragalactic radio sources, the Very Long Baseline Array (VLBA) was used at 5.0GHz to obtain phase-referenced images of 76 sources in the NOAO Bootes field. These 76 sources were selected from the Faint Images of the Radio Sky at Twenty cm (FIRST) catalog to have peak flux densities above 10mJy at 5" resolution and deconvolved major diameters of less than 3" at 1.4GHz. Of these faint radio sources, 57 were identified with accretion-powered radio galaxies and quasars brighter than 25.5mag in the optical I band. On Very Large Array (VLA) scales at 1.4GHz, a measure of the compactness of the faint sources (the ratio of the peak flux density from FIRST to the integrated flux density from the NRAO VLA Sky Survey catalog) spans the full range of possibilities arising from source-resolution effects.
- ID:
- ivo://CDS.VizieR/J/ApJ/795/63
- Title:
- Faraday rotation from magnesium II absorbers
- Short Name:
- J/ApJ/795/63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Strong singly ionized magnesium (Mg II) absorption lines in quasar spectra typically serve as a proxy for intervening galaxies along the line of sight. Previous studies have found a correlation between the number of these Mg II absorbers and the Faraday rotation measure (RM) at ~5 GHz. We cross-match a sample of 35752 optically identified non-intrinsic Mg II absorption systems with 25649 polarized background radio sources for which we have measurements of both the spectral index and RM at 1.4 GHz. We use the spectral index to split the resulting sample of 599 sources into flat-spectrum and steep-spectrum subsamples. We find that our flat-spectrum sample shows significant (~3.5{sigma}) evidence for a correlation between Mg II absorption and RM at 1.4 GHz, while our steep-spectrum sample shows no such correlation. We argue that such an effect cannot be explained by either luminosity or other observational effects, by evolution in another confounding variable, by wavelength-dependent polarization structure in an active galactic nucleus, by the Galactic foreground, by cosmological expansion, or by partial coverage models. We conclude that our data are most consistent with intervenors directly contributing to the Faraday rotation along the line of sight, and that the intervening systems must therefore have coherent magnetic fields of substantial strength (B{bar}=1.8+/-0.4{mu}G). Nevertheless, the weak nature of the correlation will require future high-resolution and broadband radio observations in order to place it on a much firmer statistical footing.
- ID:
- ivo://CDS.VizieR/J/ApJ/707/114
- Title:
- Faraday rotation in Cen A
- Short Name:
- J/ApJ/707/114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of an Australia Telescope Compact Array 1.4GHz spectropolarimetric aperture synthesis survey of 34deg^2^ centered on Centaurus A-NGC 5128. A catalog of 1005 extragalactic compact radio sources in the field to a continuum flux density of 3mJy/beam is provided along with a table of Faraday rotation measures (RMs) and linear polarized intensities for the 28% of sources with high signal to noise in linear polarization. We use the ensemble of 281 background polarized sources as line-of-sight probes of the structure of the giant radio lobes of Centaurus A. This is the first time such a method has been applied to radio galaxy lobes and we explain how it differs from the conventional methods that are often complicated by depth and beam depolarization effects. Assuming a magnetic field strength in the lobes of 1.3B1uG, where B1=1 is implied by equipartition between magnetic fields and relativistic particles, the upper limit we derive on the maximum possible difference between the average RM of 121 sources behind Centaurus A and the average RM of the 160 sources along sightlines outside Centaurus A implies an upper limit on the volume-averaged thermal plasma density in the giant radio lobes of <ne><5x10^-5^B1^-1^cm^-3^. We use an RM structure function analysis and report the detection of a turbulent RM signal, with rms=17rad/m^2^ and scale size 0.3deg, associated with the southern giant lobe. We cannot verify whether this signal arises from turbulent structure throughout the lobe or only in a thin skin (or sheath) around the edge, although we favor the latter. The RM signal is modeled as possibly arising from a thin skin with a thermal plasma density equivalent to the Centaurus intragroup medium density and a coherent magnetic field that reverses its sign on a spatial scale of 20kpc. For a thermal density of n1 10^-3^cm^-3^, the skin magnetic field strength is 0.8n1^-1^uG.
