- ID:
- ivo://CDS.VizieR/J/AJ/125/465
- Title:
- Phoenix Deep Survey 1.4-GHz microJy Catalog
- Short Name:
- J/AJ/125/465
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The initial Phoenix Deep Survey (PDS) observations with the Australia Telescope Compact Array have been supplemented by additional 1.4 GHz observations over the past few years. Here we present details of the construction of a new mosaic image covering an area of 4.56 deg2, an investigation of the reliability of the source measurements, and the 1.4 GHz source counts for the compiled radio catalog. The mosaic achieves a 1-sigma rms noise of 12 microJy at its most sensitive, and a homogeneous radio-selected catalog of over 2000 sources reaching flux densities as faint as 60 microJy has been compiled. The source parameter measurements are found to be consistent with the expected uncertainties from the image noise levels and the Gaussian source fitting procedure. A radio-selected sample avoids the complications of obscuration associated with optically selected samples, and by utilizing complementary PDS observations, including multicolor optical, near-infrared, and spectroscopic data, this radio catalog will be used in a detailed investigation of the evolution in star formation spanning the redshift range 0 < z < 1. The homogeneity of the catalog ensures a consistent picture of galaxy evolution can be developed over the full cosmologically significant redshift range of interest.
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- ID:
- ivo://CDS.VizieR/J/A+A/632/A66
- Title:
- PKS 1549-79 ALMA data cubes & continuum images
- Short Name:
- J/A+A/632/A66
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present CO(1-0) and CO(3-2) Atacama Large Millimeter/submillimeter Array observations of the molecular gas in PKS 1549-79, as well as mm and very long baseline interferometry 2.3-GHz continuum observations of its radio jet. PKS 1549-79 is one of the closest young, radio-loud quasars caught in an on-going merger in which the active galactic nucleus (AGN) is in the first phases of its evolution. We detect three structures tracing the accretion and the outflow of molecular gas: kpc-scale tails of gas accreting onto PKS1549-79 from a merger, a circumnuclear disc in the inner few hundred parsec, and a very broad (>2300km/s) component detected in CO(1-0) at the position of the AGN. Thus, in PKS 1549-79 we see the co-existence of accretion and the ejection of gas. The line ratio CO(3-2)/CO(1-0) suggests that the gas in the circumnuclear-disc has both high densities and high kinetic temperatures. We estimate a mass outflow rate of at least 650M_{sun}_/yr. This massive outflow is confined to the inner region (r<120pc) of the galaxy, which suggests that the AGN drives the outflow. Considering the amount of molecular gas available in the central nuclear disc and the observed outflow rate, we estimate a time scale of 10^5^yr over which the AGN would be able to destroy the circumnuclear disc, although gas from the merger may come in from larger radii, rebuilding this disc at the same time. The AGN appears to self-regulate gas accretion to the centre and onto the super-massive black hole. Surprisingly, from a comparison with Hubble Space Telescope data, we find that the ionised gas outflow is more extended. Nevertheless, the warm outflow is about two orders of magnitude less massive than the molecular outflow. PKS 1549-79 does not seem to follow the scaling relation between bolometric luminosity and the relative importance of warm ionised and molecular outflows claimed to exist for other AGN. We argue that, although PKS 1549-79 hosts a powerful quasar nucleus and an ultra-fast outflow, the radio jet plays a significant role in producing the outflow, which creates a cocoon of disturbed gas that expands into the circumnuclear disc.
- ID:
- ivo://CDS.VizieR/J/A+A/634/A9
- Title:
- PKS 1549-79 ALMA data cubes & continuum images
- Short Name:
- J/A+A/634/A9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new observations of Fornax A taken at ~1GHz with the MeerKAT telescope and at ~6GHz with the Sardinia Radio Telescope (SRT). The sensitive (noise ~16uJy/beam), high-resolution (<10'') MeerKAT images show that the lobes of Fornax A have a double-shell morphology, where dense filaments are embedded in a diffuse and extended cocoon. We study the spectral properties of these components by combining the MeerKAT and SRT observations with archival data between 84MHz and 217GHz. For the first time, we show that multiple episodes of nuclear activity must have formed the extended radio lobes. The modelling of the radio spectrum suggests that the last episode of injection of relativistic particles into the lobes started ~24Myr ago and stopped 12Myr ago. More recently (~3Myr ago), a less powerful and short (<1Myr) phase of nuclear activity generated the central jets. Currently, the core may be in a new active phase. It appears that Fornax A is rapidly flickering. The dense environment around Fornax A has lead to a complex recent merger history for this galaxy, including mergers spanning a range of gas contents and mass ratios, as shown by the analysis of the galaxy's stellar- and cold-gas phases. This complex recent history may be the cause of the rapid, recurrent nuclear activity of Fornax A.
- ID:
- ivo://CDS.VizieR/J/ApJ/733/69
- Title:
- Polarized DRAO sources
- Short Name:
- J/ApJ/733/69
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Dominion Radio Astrophysical Observatory Deep Field polarization study has been matched with the Spitzer Wide-Area Infrared Extragalactic Survey of the European Large Area Infrared Space Observatory Survey North 1 field. We have used Very Large Array observations with a total intensity rms of 87uJy/beam to match SWIRE counterparts to the radio sources. Infrared color analysis of our radio sample shows that the majority of polarized sources are elliptical galaxies with an embedded active galactic nucleus. Using available redshift catalogs, we found 429 radio sources of which 69 are polarized with redshifts in the range of 0.04<z<3.2. We find no correlation between redshift and percentage polarization for our sample. However, for polarized radio sources, we find a weak correlation between increasing percentage polarization and decreasing luminosity.
- ID:
- ivo://CDS.VizieR/J/A+A/418/1
- Title:
- Radio continuum spectra in Virgo cluster region
- Short Name:
- J/A+A/418/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New radio continuum observations of galaxies in the Virgo cluster region at 4.85, 8.6, and 10.55GHz are presented. These observations are combined with existing measurements at 1.4 and 0.6GHz. The sample includes 81 galaxies where spectra with more than two frequencies could be derived. Galaxies that show a radio-FIR excess exhibit central activity (HII, LINER,AGN). The four Virgo galaxies with the highest absolute radio excess are found within 2 degrees of the center of the cluster. Galaxies showing flat radio spectra also host active centers. There is no clear trend between the spectral index and the galaxy's distance to the cluster center.
- ID:
- ivo://CDS.VizieR/J/A+A/472/785
- Title:
- Radio continuum survey of M33
- Short Name:
- J/A+A/472/785
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the exponential scale length of total radio emission, the spectral index distribution, and the linear radio polarization in the Scd galaxy M33. Observations were carried out using the 3.6cm dual channel and the 6.2cm four-channel receivers of the 100-m Effelsberg telescope along with the L-band VLA D-array at 20cm. High spatial resolution and sensitivity in both total and linearly polarized radio continuum emission from M33 were achieved. We found considerable extended emission, not only from the main arms IS and IN, but also from the weaker arms. The large-scale magnetic field exhibits well-ordered spiral structure with almost the same orientation as that of the optical spiral arms; however, it does not show a clear structural correlation or anti-correlation with the optical arms. There is a north-south asymmetry in polarization that is frequency-dependent. We found that the ring mean spectral index versus radius increases faster beyond R=4kpc. At each wavelength, the exponential scale length is larger inside than outside R=4kpc. From the larger scale lengths at R<4kpc, we conclude that star-forming regions are mainly spread over the region R<4kpc without a dominant nuclear concentration. Furthermore, at R>4kpc, a spatial correlation between cosmic rays and star-forming regions may exist. From the behavior of the mean spectral indices obtained from different pairs of the radio continuum data at 3.6, 6.2, and 20cm, we confirm that a decrease in the thermal fraction causes an increase in the spectral index.
- ID:
- ivo://CDS.VizieR/J/A+A/574/A4
- Title:
- Radio image of Luminous Infrared Galaxies
- Short Name:
- J/A+A/574/A4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Luminous Infrared Galaxies (LIRGs) are systems enshrouded in dust, which absorbs most of their optical/UV emission and radiates it again in the mid- and far-infrared. Radio observations are largely unaffected by dust obscuration, enabling us to study the central regions of LIRGs in an unbiased manner. The main goal of this project is to examine how the radio properties of local LIRGs relate to their infrared spectral characteristics. Here we present an analysis of the radio continuum properties of a subset of the Great Observatories All-sky LIRG Survey (GOALS), which consists of 202 nearby systems (z<0.088). Our radio sample consists of 35 systems, containing 46 individual galaxies, that were observed at both 1.49 and 8.44GHz with the VLA with a resolution of about 1-arcsec (FWHM). The aim of the project is to use the radio imagery to probe the central kpc of these LIRGs in search of Active Galactic Nuclei (AGN). We used the archival data at 1.49 and 8.44GHz to create radio-spectral-index maps using the standard relation between flux density S{nu} and frequency {nu}, S{nu}~{nu}^-{alpha}^, where {alpha} is the radio spectral index. By studying the spatial variations in {alpha}, we classified the objects as radio-AGN, radio-SB, and AGN/SB (a mixture). We identified the presence of an active nucleus using the radio morphology, deviations from the radio/infrared correlation, and spatially resolved spectral index maps, and then correlated this to the usual mid-infrared ([NeV]/[NeII] and [OIV]/[NeII] line ratios and equivalent width of the 6.2um PAH feature) and optical (BPT diagram) AGN diagnostics. We find that 21 out of the 46 objects in our sample (~45%) are radio-AGN, 9 out of the 46 (~20%) are classified as starbursts (SB) based on the radio analysis, and 16 (~35%) are AGN/SB. After comparing to other AGN diagnostics we find 3 objects out of the 46 (~7%) that are identified as AGN based on the radio analysis, but are not classified as such based on the mid-infrared and optical AGN diagnostics presented in this study.
- ID:
- ivo://CDS.VizieR/J/A+A/575/A55
- Title:
- Radio jet emission from GeV-emitting NLSy1
- Short Name:
- J/A+A/575/A55
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- With the current study we aim at gaining understanding on the properties of radio emission and the assumed jet from four radio loud and {gamma}-ray loud Narrow Line Seyfert 1 galaxies i.e. Seyfert 1 galaxies with emission lines at the low-end of the FWHM distribution. The ultimate goal is twofold; first, the investigation whether a relativistic jet is operating at the source giving out the radio output observed and second, the quantification of the jet characteristics in order to understand possible similarities and differences with the jets found in typical blazars. The current study relies on the most systematic monitoring of radio loud and {gamma}-ray detected Narrow Line Seyfert 1 galaxies in the cm and mm radio bands conducted with the Effelsberg 100-m and IRAM 30-m telescopes. It covers the longest time baselines and the most radio frequencies, to date. This dataset of multi- wavelength, long-term radio light curves is analysed from a number of perspectives. A novel algorithm is introduced in order to extract sensible variability parameters (mainly amplitudes and timescales) which are then used for the computation of variability brightness temperatures and the corresponding Doppler factors. The jet powers are computed from the light curves to estimate the energy output and compare it with typical blazars. The dynamics of radio Spectra Energy Distributions are examined for understanding the mechanism causing the variability. The length of the available light curves for 3 of the 4 sources in the sample allowed a firm understanding of the general behaviour of the sources. They all display intensive variability which seems to be happening at a pace rather faster than what is generally seen in blazars. The flaring events become progressively more prominent as the frequency increases and show intensive spectral evolution indicative of shock evolution. The variability brightness temperatures and the associated Doppler factors are rather moderate implying a mildly relativistic jet. The computed jet powers show very energetic flows. The radio polarisation in one case, clearly implies the presence of a quiescent jet underlying recursive flaring activity. Finally, in one case, the sudden disappearance of a {gamma}-ray flare below some critical frequency in our band, urges for further investigation of the possible mechanism causing the evolution of broadband events. Despite the generally lower flux densities the sources appear to show all typical characteristics seen in blazars powered by relativistic jets. Intensive variability, spectral evolution across the different bands following evolutionary paths explained by traveling shocks, Doppler factors indicating mildly relativistic speeds.
- ID:
- ivo://CDS.VizieR/J/A+A/520/A62
- Title:
- Radio-optical scrutiny of compact AGN
- Short Name:
- J/A+A/520/A62
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the correlations between the VLBA (Very Long Baseline Array) radio emission at 15GHz, extended emission at 151MHz, and optical nuclear emission at 5100{AA} for a complete sample of 135 compact jets. We use the partial Kendall's tau correlation analysis to check the link between radio properties of parsec-scale jets and optical nuclear luminosities of host active galactic nuclei (AGN).
- ID:
- ivo://CDS.VizieR/J/AJ/102/1663
- Title:
- Radio properties of extragal. IRAS sources
- Short Name:
- J/AJ/102/1663
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog presents radio and optical identifications of extragalactic IRAS sources from the IRAS Faint Source Catalog |b| > 50{deg} (Moshir et al., 1989 Cat. <II/156>). Sources with flux density > 0.2 at 60 microns and with S_60_ > S_12_ were identified by position coincidence with radio sources stronger than 25 mJy and lying north of declination = 5{deg} on the Green Bank 4.85 GHz sky map. Published VLA maps, new 4.86 GHz VLA maps made with 15 arcsec resolution, and accurate optical positions were used to confirm 122 candidate identifications. This catalog contains a merged version of tables 1 and 2 from the paper.