- ID:
- ivo://CDS.VizieR/J/A+A/569/A115
- Title:
- TANAMI monitoring of Centaurus A.
- Short Name:
- J/A+A/569/A115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Centaurus A (Cen A) is the closest radio-loud active galactic nucleus. Very Long Baseline Interferometry (VLBI) enables us to study the spectral and kinematic behavior of the radio jet-counterjet system on milliarcsecond scales, providing essential information for jet emission and propagation models. In the framework of the TANAMI monitoring, we investigate the kinematics and complex structure of Cen A on subparsec scales. We have been studying the evolution of the central parsec jet structure of Cen A for over 3.5-years. The proper motion analysis of individual jet components allows us to constrain jet formation and propagation and to test the proposed correlation of increased high-energy flux with jet ejection events. Cen A is an exceptional laboratory for such a detailed study because its proximity translates to unrivaled linear resolution, where one milliarcsecond corresponds to 0.018pc. As a target of the southern-hemisphere VLBI monitoring program TANAMI, observations of Cen A are done approximately every six months at 8.4GHz with the Australian Long Baseline Array (LBA) and associated telescopes in Antarctica, Chile, New Zealand, and South Africa, complemented by quasi-simultaneous 22.3GHz observations. The first seven epochs of high-resolution TANAMI VLBI observations at 8.4GHz of Cen A are presented, resolving the jet on (sub-)milliarcsecond scales. They show a differential motion of the subparsec scale jet with significantly higher component speeds farther downstream where the jet becomes optically thin. We determined apparent component speeds within a range of 0.1c to 0.3c and identified long-term stable features. In combination with the jet-to-counterjet ratio, we can constrain the angle to the line of sight to {theta}~12{deg}-45{deg}. The high-resolution kinematics are best explained by a spine-sheath structure supported by the downstream acceleration occurring where the jet becomes optically thin. On top of the underlying, continuous flow, TANAMI observations clearly resolve individual jet features. The flow appears to be interrupted by an obstacle causing a local decrease in surface brightness and circumfluent jet behavior. We propose a jet-star interaction scenario to explain this appearance. The comparison of jet ejection times to high X-ray flux phases yields a partial overlap of the onset of the X-ray emission and increasing jet activity, but the limited data do not support a robust correlation.
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- ID:
- ivo://CDS.VizieR/J/A+A/627/A148
- Title:
- TANAMI radio galaxies I
- Short Name:
- J/A+A/627/A148
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the framework of the TANAMI multi-wavelength and VLBI monitoring, we study the evolution of the parsec-scale radio emission in radio galaxies in the southern hemisphere and their relationship to the gamma-ray properties of the sources. Our study investigates systematically, for the first time, the relationship between the two energy regimes in radio galaxies. In this first paper, we focus on Fermi-LAT-detected sources. The TANAMI program monitors a large sample of radio-loud AGN at 8.4GHz and 22.3GHz with the Australian Long Baseline Array(LBA) and associated telescopes in Antarctica, Chile, New Zealand and South Africa. We perform a kinematic analysis for five gamma-ray detected radio galaxies using multi-epoch 8.4 GHz VLBI images, deriving limits on intrinsic jet parameters such as speed and viewing angle. We analyzed103 months of Fermi-LAT data in order to study possible connections between the gamma-ray properties and the pc-scale jets of Fermi-LAT-detected radio galaxies, both in terms of variability and average properties. We discuss the individual source results and draw preliminary conclusions on sample properties including published VLBI results from the MOJAVE survey, with a total of fifteen sources. We find that the first gamma-ray detection of Pictor A might be associated with the passage of a new VLBI component through the radio core, which appears to be a defining feature of high-energy emitting Fanaroff-Riley type II radio galaxies. For the peculiar AGN PKS 0521-36, we detect subluminal parsec-scale jet motions, and we confirm the presence of fast gamma-ray variability in the source down to timescales of 6 hours, which is not accompanied by variations in the VLBI jet. We robustly confirm the presence of significant superluminal motion, up to {beta}_app_~3, in the jet of the TeV radio galaxy PKS 0625-35. Our VLBI results constrain the jet viewing angle to be {theta}<53{deg}, allowing for the possibility of a closely aligned jet. Finally, by analyzing the first pc-scale multi-epoch images of the prototypical Compact Symmetric Object (CSO) PKS 1718-649, we place an upper limit on the separation speed between the two mini-lobes, which in turn allows us to derive a lower limit on the age of the source.Conclusions.We can draw some preliminary conclusions on the relationship between pc-scale jets and gamma-ray emission in radio galaxies, basedonFermi-LAT-detected sources with available multi-epoch VLBI measurements. We find that the VLBI core flux density correlates with the gamma-ray flux, as seen in blazars. On the other hand, the gamma-ray luminosity does not show any dependence on the core brightness temperature and core dominance, two common indicators of jet Doppler boosting. This seems to indicate that gamma-ray emission in radio galaxies is not driven by orientation-dependent effects, as in blazars, which is consistent with the unified model of jetted AGN.
- ID:
- ivo://CDS.VizieR/J/A+A/641/A152
- Title:
- TANAMI radio galaxies II
- Short Name:
- J/A+A/641/A152
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the second paper in our series studying the evolution of parsec-scale radio emission in radio galaxies in the southern hemisphere. Following our study of the radio and high-energy properties of gamma-ray-emitting sources, here we investigate the kinematic and spectral properties of the parsec-scale jets of radio galaxies that have not yet been detected by the Fermi Large Area Telescope (Fermi-LAT) instrument on board NASA's Fermi Gamma-ray Space Telescope. For many sources, these results represent the first milliarcsecond resolution information in the literature. These studies were conducted within the framework of the Tracking Active Nuclei with Austral Milliarcsecond Interferometry (TANAMI) monitoring program and in the context of high-energy gamma-ray observations from Fermi-LAT. We take advantage of the regular 8.4GHz and 22.3GHz Very Long Baseline Interferometry (VLBI) observations provided by the TANAMI monitoring program, and explore the kinematic properties of six gamma-ray-faint radio galaxies. We complement this with ~8.5 years of Fermi-LAT data, deriving updated upper limits on the gamma-ray emission from this subsample of TANAMI radio galaxies. We include publicly available VLBI kinematics of gamma-ray-quiet radio galaxies monitored by the MOJAVE program and perform a consistent Fermi-LAT analysis. We combine these results with those from our previous paper to construct the largest sample of radio galaxies with combined VLBI and gamma-ray measurements to date. The connection between parsec-scale jet emission and high-energy properties in the misaligned jets of radio galaxies is explored. We report for the first time evidence of superluminal motion up to beta_app_=3.6 in the jet of the gamma-ray-faint radio galaxy PKS 2153-69. We find a clear trend of higher apparent speed as a function of distance from the jet core, which indicates that the jet is still being accelerated on scales of tens of parsecs, or ~10^5^R_{sun}_, corresponding to the end of the collimation and acceleration zone in nearby radio galaxies. We find evidence of subluminal apparent motion in the jets of PKS 1258-321 and IC 4296, and no measurable apparent motion for PKS 1549-79, PKS 1733-565 and PKS 2027-308. For all these sources, TANAMI provides the first multi-epoch kinematic analysis on parsec scales. We then compare the VLBI properties of gamma-ray-detected and undetected radio galaxies, and find that the two populations show a significantly different distribution of median core flux density, and, possibly, of median core brightness temperature. In terms of correlation between VLBI and gamma-ray properties, we find a significant correlation between median core flux density and gamma-ray flux, but no correlation with typical Doppler boosting indicators such as median core brightness temperature and core dominance. Our study suggests that high-energy emission from radio galaxies is related to parsec-scale radio emission from the inner jet, but is not driven by Doppler boosting effects, in contrast to the situation in their blazar counterparts. This implies that gamma-ray loudness does not necessarily reflect a higher prevalence of boosting effects.
- ID:
- ivo://CDS.VizieR/J/MNRAS/357/1231
- Title:
- Texas-Oxford NVSS (TONS) radio galaxies
- Short Name:
- J/MNRAS/357/1231
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a clustering analysis of the Texas-Oxford NVSS Structure (TONS) radio galaxy redshift survey. This complete flux-limited survey consists of 268 radio galaxies with spectroscopic redshifts in three separate regions of the sky covering a total of 165{deg}^2^. By going to faint radio flux densities (S_1.4_>=3mJy) but imposing relatively bright optical limits (E~R~19.5), the TONS sample is optimized for looking at the clustering properties of low-luminosity radio galaxies in a region of moderate (0<=z<=0.5) redshifts. Description:
- ID:
- ivo://CDS.VizieR/J/MNRAS/485/1188
- Title:
- The ALMA Calibrator Catalogue
- Short Name:
- J/MNRAS/485/1188
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new catalogue of ALMA observations, the ALMA Calibrator Catalogue (ACC), collecting 3361 bright, compact radio sources, mostly blazars, used as calibrators. These sources were observed between 2011 May and 2018 July, for a total of 47115 pointings in different bands and epochs. A search in the online data bases yielded redshift measurements for 2245 sources.
- ID:
- ivo://CDS.VizieR/J/AJ/157/81
- Title:
- The Arecibo PPS Survey. I. Harvesting ALFALFA
- Short Name:
- J/AJ/157/81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report a multi-objective campaign of targeted 21 cm H I line observations of sources selected from the Arecibo Legacy Fast Arecibo L-band Feed Array (ALFALFA) survey and galaxies identified by their morphological and photometric properties in the Sloan Digital Sky Survey. The aims of this program have been (1) to confirm the reality of some ALFALFA sources whose enigmatic nature suggest additional multiwavelength observations; (2) to probe the low signal-to-noise ratio (S/N) regime, below the ALFALFA reliability limit; and (3) to explore the feasibility of using optical morphology, color, and surface brightness to identify gas-rich objects in the region of the Pisces-Perseus Supercluster (PPS) whose H I fluxes are below the ALFALFA sensitivity limit at that distance. As expected, the reliability of ALFALFA detections depends strongly on the S/N of the H I line signal and its coincidence with a probable stellar counterpart identified by its optical properties, suggestive of ongoing star formation. The identification of low-mass, star-forming populations enables targeted H I line observations to detect galaxies with H I line fluxes below the ALFALFA sensitivity limits in fixed local volumes (D<100 Mpc). The method explored here serves as the basis for extending the sample of gas-bearing objects as part of the ongoing Arecibo Pisces-Perseus Supercluster Survey (APPSS).
- ID:
- ivo://CDS.VizieR/J/ApJS/199/27
- Title:
- The ATLBS Extended Source Sample
- Short Name:
- J/ApJS/199/27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Based on the Australia Telescope Low Brightness Survey (ATLBS) we present a sample of extended radio sources and derive morphological properties of faint radio sources. One hundred nineteen radio galaxies form the ATLBS Extended Source Sample (ATLBS-ESS) consisting of all sources exceeding 30" in extent and integrated flux densities exceeding 1mJy. We give structural details along with information on galaxy identifications and source classifications. The ATLBS-ESS, unlike samples with higher flux-density limits, has almost equal fractions of FR-I and FR-II radio galaxies, with a large fraction of the FR-I population exhibiting 3C31-type structures. Significant asymmetry in lobe extents appears to be a common occurrence in the ATLBS-ESS FR-I sources compared with FR-II sources. We present a sample of 22 FR-Is at z>0.5 with good structural information. The detection of several giant radio sources, with size exceeding 0.7Mpc, at z>1 suggests that giant radio sources are not less common at high redshifts. The ESS also includes a sample of 28 restarted radio galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJ/714/1305
- Title:
- The Deep SWIRE Field (DSF) IV.
- Short Name:
- J/ApJ/714/1305
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of a 20cm selected sample in the Deep Spitzer Wide-area InfraRed Extragalactic Legacy Survey Very Large Array Field, reaching a 5{sigma} limiting flux density at the image center of S_1.4GHz_~13.5uJy. In a 0.6x0.6deg^2^ field, we are able to assign an optical/IR counterpart to 97% of the radio sources. Up to 11 passbands from the NUV to 4.5um are then used to sample the spectral energy distribution (SED) of these counterparts in order to investigate the nature of the host galaxies. By means of an SED template library and stellar population synthesis models, we estimate photometric redshifts, stellar masses, and stellar population properties, dividing the sample into three sub-classes of quiescent, intermediate, and star-forming galaxies. We focus on the radio sample in the redshift range 0.3<z<1.3 where we estimate to have a redshift completeness higher than 90% and study the properties and redshift evolution of these sub-populations.
- ID:
- ivo://CDS.VizieR/J/ApJS/126/133
- Title:
- The FIRST bright quasar survey. II.
- Short Name:
- J/ApJS/126/133
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used the Very Large Array (VLA) FIRST survey and the Automated Plate Measuring Facility (APM) catalog of the Palomar Observatory Sky Survey I (POSS-I) plates as the basis for constructing a new radio-selected sample of optically bright quasars. This is the first radio-selected sample that is competitive in size with current optically selected quasar surveys. Using only two basic criteria, radio-optical positional coincidence and optical morphology, quasars and BL Lac objects can be identified with 60% selection efficiency; the efficiency increases to 70% for objects fainter than 17 mag. We show that a more sophisticated selection scheme can predict with better than 85% reliability which candidates will turn out to be quasars. This paper presents the second installment of the FIRST Bright Quasar Survey (FBQS), with a catalog of 636 quasars distributed over 2682 deg^2^. The quasar sample is characterized and all spectra are displayed.
- ID:
- ivo://CDS.VizieR/J/ApJS/135/227
- Title:
- The FIRST bright quasar survey. III.
- Short Name:
- J/ApJS/135/227
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of an extension of the FIRST Bright Quasar Survey (FBQS) to the South Galactic cap, and to a fainter optical magnitude limit. Radio source counterparts with SERC R magnitudes brighter than 18.9 which meet the other FBQS criteria are included. We supplement this list with a modest number of additional objects to test our completeness for quasars with extended radio morphologies. The survey covers 589deg^2^ in two equatorial strips in the southern cap. We have obtained spectra for 86% of the 522 candidates and find 321 radio-selected quasars of which 264 are reported here for the first time. A comparison of this fainter sample with the FBQS sample shows the two to be generally similar. Fourteen new broad absorption line (BAL) quasars are included in this sample. When combined with the previously identified BAL quasars in our earlier papers, we can discern a break in the frequency of BAL quasars with radio loudness, namely that the relative number of high-ionization BAL quasars drops by a factor of 4 for quasars with a radio-loudness parameter R*>100.
