- ID:
- ivo://CDS.VizieR/J/AJ/130/1418
- Title:
- AGN jet kinematics
- Short Name:
- J/AJ/130/1418
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present total and polarized intensity images of 15 active galactic nuclei obtained with the Very Long Baseline Array at 7mm (43GHz) wavelength at 17 epochs from 1998 March to 2001 April. At some epochs the images are accompanied by nearly simultaneous polarization measurements at 3mm (86GHz) with the Berkeley-Illinois-Maryland Association (BIMA) array (Hat Creek, California), 1.35/0.85mm (230/350GHz) with the James Clerk Maxwell Telescope (JCMT; using SCUBA and its polarimeter, and at the Steward Observatory 1.5m telescope (Mount Lemmon, Arizona) with the Two-Holer Polarimeter/Photometer over an effective wavelength range of ~6000-7000{AA}. Here we analyze the 7mm images to define the properties of the jets of two radio galaxies, five BL Lac objects, and eight quasars on angular scales >~0.1mas. We determine the apparent velocities of 106 features in the jets.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AZh/93/605
- Title:
- AGN long-term variability
- Short Name:
- J/AZh/93/605
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Abstract-A complete sample of 104 bright active galactic nuclei (AGNs) from the "Planck" catalog (early results) were observed at 36.8GHz with the 22-m radio telescope of the Crimean Astrophysical Observatory (CrAO).Variability indices of the sources at this frequency were determined based on data from theWMAP space observatory, theMetsahovi RadioObservatory (Finland), and the CrimeanAstrophysical Observatory. New observational results confirm that the variability of these AGNs is stronger in the millimeter than at other radio wavelengths. The variability indices probably change as a result of the systematic decrease in the AGN flux densities in the transition to the infrared. Some radio sources demonstrate significant flux-density variations, including decreases, which sometimes cause them to fall out of the analysed sample. The change of the variability index in the millimeter is consistent with the suggestion that this variability is due to intrinsic processes in binary supermassive black holes at an evolutionary stage close to coalescence. All 104 of the sources studied are well known objects that are included in various radio catalogs and have flux densities exceeding 1Jy at 36.8GHz.
- ID:
- ivo://CDS.VizieR/J/other/APh/26.282
- Title:
- AGN neutrino source candidates
- Short Name:
- J/other/APh/26.2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The sensitivity of a search for sources of TeV neutrinos can be improved by grouping potential sources together into generic classes in a procedure that is known as source stacking. In this paper, we define catalogs of Active Galactic Nuclei (AGN) and use them to perform a source stacking analysis. The grouping of AGN into classes is done in two steps: first, AGN classes are defined, then, sources to be stacked are selected assuming that a potential neutrino flux is linearly correlated with the photon luminosity in a certain energy band (radio, IR, optical, keV, GeV, TeV). Lacking any secure detailed knowledge on neutrino production in AGN, this correlation is motivated by hadronic AGN models, as briefly reviewed in this paper. The source stacking search for neutrinos from generic AGN classes is illustrated using the data collected by the AMANDA-II high-energy neutrino detector during the year 2000. No significant excess for any of the suggested groups was found.
- ID:
- ivo://CDS.VizieR/J/ApJS/171/61
- Title:
- All-Sky Survey of Flat-Spectrum Radio Sources
- Short Name:
- J/ApJS/171/61
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have assembled an 8.4GHz survey of bright, flat-spectrum ({alpha}>-0.5) radio sources with nearly uniform extragalactic (|b|>10{deg}) coverage for sources brighter than S_4.8GHz_=65mJy. The catalog is assembled from existing observations (especially CLASS and the Wright et al., Cat VIII/38, PMN-CA survey), augmented by reprocessing of archival VLA and ATCA data and by new observations to fill in coverage gaps. We refer to this program as CRATES, the Combined Radio All-Sky Targeted Eight GHz Survey. The resulting catalog provides precise positions, subarcsecond structures, and spectral indices for some 11000 sources. We describe the morphology and spectral index distribution of the sample and comment on the survey's power to select several classes of interesting sources, especially high-energy blazars. Comparison of CRATES with other high-frequency surveys also provides unique opportunities for identification of high-power radio sources.
- ID:
- ivo://CDS.VizieR/J/MNRAS/473/4937
- Title:
- AllWISE ctp to ROSAT/2RXS & XMMSLEW2 catalogs
- Short Name:
- J/MNRAS/473/4937
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We release the AllWISE counterparts and Gaia matches to 106573 and 17665 X-ray sources detected in the ROSAT 2RXS and XMMSL2 surveys with |b|>15{deg}. These are the brightest X-ray sources in the sky, but their position uncertainties and the sparse multi-wavelength coverage until now rendered the identification of their counterparts a demanding task with uncertain results. New all-sky multi-wavelength surveys of sufficient depth, like AllWISE and Gaia, and a new Bayesian statistics based algorithm, NWAY, allow us, for the first time, to provide reliable counterpart associations. NWAY extends previous distance and sky density based association methods and, using one or more priors (e.g. colours, magnitudes), weights the probability that sources from two or more catalogues are simultaneously associated on the basis of their observable characteristics. Here, counterparts have been determined using a Wide-field Infrared Survey Explorer (WISE) colour-magnitude prior. A reference sample of 4524 XMM/Chandra and Swift X-ray sources demonstrates a reliability of 94.7 per cent (2RXS) and 97.4 per cent (XMMSL2). Combining our results with Chandra-COSMOS data, we propose a new separation between stars and AGN in the X-ray/WISE flux-magnitude plane, valid over six orders of magnitude. We also release the NWAY code and its user manual. NWAY was extensively tested with XMM-COSMOS data. Using two different sets of priors, we find an agreement of 96 per cent and 99 per cent with published Likelihood Ratio methods. Our results were achieved faster and without any follow-up visual inspection. With the advent of deep and wide area surveys in X-rays (e.g. SRG/eROSITA, Athena/WFI) and radio (ASKAP/EMU, LOFAR, APERTIF, etc.) NWAY will provide a powerful and reliable counterpart identification tool. See for all the options the Nway manual at https://github.com/JohannesBuchner/nway/raw/master/doc/nway-manual.pdf
- ID:
- ivo://CDS.VizieR/J/A+A/630/A59
- Title:
- ALMA continuum-subtracted datacubes for 48 QSOs
- Short Name:
- J/A+A/630/A59
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the stacking analysis of a sample of 48 quasi-stellar objects (QSOs) at 4.5<z<7.1 detected by the Atacama Large Millimetre Array (ALMA) in the [CII] {lambda}158um emission line to investigate the presence and the properties of massive, cold outflows associated with broad wings in the [CII] profile. The high sensitivity reached through this analysis allows us to reveal very broad [CII] wings tracing the presence of outflows with velocities in excess of 1000km/s. We find that the luminosity of the broad [CII] emission increases with LAGN, while it does not significantly depend on the star formation rate of the host galaxy, indicating that the central active galactic nucleus (AGN) is the main driving mechanism of the [CII] outflows in these powerful, distant QSOs. From the stack of the ALMA cubes, we derive an average outflow spatial extent of ~3.5kpc. The average atomic neutral mass outflow rate inferred from the stack of the whole sample is dM_out_/dt~100M_{sun}_/yr, while for the most luminous systems it increases to ~200M_{sun}_/yr. The associated outflow kinetic power is about 0.1% of L_AGN_, while the outflow momentum rate is ~L_AGN_/c or lower, suggesting that these outflows are either driven by radiation pressure onto dusty clouds or, alternatively, are driven by the nuclear wind and energy conserving but with low coupling with the interstellar medium. We discuss the implications of the resulting feedback effect on galaxy evolution in the early Universe.
- ID:
- ivo://CDS.VizieR/J/A+A/641/A97
- Title:
- ALMA Magellanic Bridge A molecular clouds
- Short Name:
- J/A+A/641/A97
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Magellanic Bridge is a tidal feature located between both Magellanic Clouds, containing young stars formed in situ. Its proximity allows high-resolution studies of molecular gas, dust and star formation in a tidal, low metallicity environment. Our goal is to characterize gas and dust emission in Magellanic Bridge A, the source with the highest 870um excess of emission found in single dish surveys. Using the ALMA telescope including the Morita Array, we mapped with sub-parsec resolution a 3arcmin, field of view centered on the Magellanic Bridge A molecular cloud, in 1.3mm continuum emission and ^12^CO(2-1 line emission. This region was also mapped in continuum at 870um and in ^12^CO(2-1) line emission at ~6pc resolution with the APEX telescope. To study its dust properties, we also use archival Herschel and Spitzer data. We combine the ALMA and APEX ^12^CO(2-1) line cubes to study the molecular gas emission. Magallanic Bridge A breaks up into two distinct molecular clouds in dust and ^12^CO(2-1) emission, which we call North and South. Dust emission in the North source, according to our best parameters from fitting the far-infrared fluxes, is ~3K colder than in the South source in correspondence to its less developed star formation. Both dust sources present large submillimeter excesses in LABOCA data: according to our best fits the excess over the modified blackbody (MBB) fit to the Spitzer/Herschel continuum is E(870um)~7 and E(870um)~3 for the North and South sources respectively. Nonetheless, we do not detect the corresponding 1.3mm continuum with ALMA. Our limits are compatible with the extrapolation of the MBB fits and therefore we cannot independently confirm the excess at this longer wavelength. The ^12^CO(2-1) emission is concentrated in two parsec-sized clouds with virial masses around 400 and 700M_{sun}_ each. Their bulk volume densities are n(H_2_)~0.7-2.6x10^3^cm^-3^, larger than typical bulk densities of Galactic molecular clouds. The ^12^CO luminosity to H_2_ mass conversion factor {alpha}_CO_ is 6.5 and 15.3M_{sun}_/(K.(km/s)pc^2^) for the North and South clouds, calculated using their respective virial masses and ^12^CO(2-1) luminosities. Gas mass estimates from our MBB fits to dust emission yields masses M~1.3x10^3^M_{sun}_ and 2.9x10^3^M_{sun}_ for North and South respectively, a factor of ~4 larger than the virial masses we infer from ^12^CO.
- ID:
- ivo://CDS.VizieR/J/ApJ/839/58
- Title:
- ALMA submm galaxies multi-wavelength data
- Short Name:
- J/ApJ/839/58
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a multi-wavelength analysis of 52 submillimeter galaxies (SMGs), identified using ALMA 870{mu}m continuum imaging in a pilot program to precisely locate bright SCUBA-2-selected submillimeter sources in the UKIDSS Ultra Deep Survey (UDS) field. Using the available deep (especially near-infrared) panoramic imaging of the UDS field at optical-to-radio wavelengths we characterize key properties of the SMG population. The median photometric redshift of the bright ALMA/SCUBA-2 UDS (AS2UDS) SMGs that are detected in a sufficient number of wavebands to derive a robust photometric redshift is z=2.65+/-0.13. However, similar to previous studies, 27% of the SMGs are too faint at optical-to-near-infrared wavelengths to derive a reliable photometric redshift. Assuming that these SMGs lie at z>~3 raises the median redshift of the full sample to z=2.9+/-0.2. A subset of 23 unlensed, bright AS2UDS SMGs have sizes measured from resolved imaging of their rest- frame far-infrared emission. We show that the extent and luminosity of the far-infrared emission are consistent with the dust emission arising from regions that are, on average, optically thick at a wavelength of {lambda}_0_>=75{mu}m (1{sigma} dispersion of 55-90{mu}m). Using the dust masses derived from our optically thick spectral energy distribution models, we determine that these galaxies have a median hydrogen column density of N_H_=9.8_-0.7_^+1.4^x10^23^cm^-2^, or a corresponding median V-band obscuration of Av=540_-40_^+80^mag, averaged along the line of sight to the source of their rest-frame ~200{mu}m emission. We discuss the implications of this extreme attenuation by dust for the multi-wavelength study of dusty starbursts and reddening-sensitive tracers of star formation.
- ID:
- ivo://CDS.VizieR/J/A+A/641/L2
- Title:
- ALMA third image of lensed quasar PKS 1830-211
- Short Name:
- J/A+A/641/L2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Strong gravitational lensing distorts our view of sources at cosmological distances but brings invaluable constraints on the mass content of foreground objects and on the geometry and properties of the Universe. We report the detection of a third continuum source toward the strongly lensed quasar PKS 1830-211 in ALMA multi-frequency observations of high dynamic range and high angular resolution. This third source is point-like and located slightly to the north of the diagonal joining the two main lensed images, A and B, 0.3" away from image B. It has a flux density that is 140 times weaker than images A and B and a similar spectral index, compatible with synchrotron emission. We conclude that this source is most likely the expected highly de-magnified third lensed image of the quasar. In addition, we detect, for the first time at millimeter wavelengths, weak and asymmetrical extensions departing from images A and B that correspond to the brightest regions of the Einstein ring seen at centimeter wavelengths. Their spectral index is steeper than that of compact images A, B, and C, which suggests that they arise from a different component of the quasar. Using the GravLens code, we explore the implications of our findings on the lensing model and propose a simple model that accurately reproduces our ALMA data and previous VLA observations. With a more precise and accurate measurement of the time delay between images A and B, the system PKS 1830-211 could help to constrain the Hubble constant to a precision of a few percent.
- ID:
- ivo://CDS.VizieR/J/A+A/659/A20
- Title:
- 2A0335+096 LOFAR images
- Short Name:
- J/A+A/659/A20
- Date:
- 04 Mar 2022 06:16:07
- Publisher:
- CDS
- Description:
- Radio observations represent a powerful probe of the physics occurring in the intracluster medium (ICM) because they trace the relativistic cosmic rays in the cluster magnetic fields, or within galaxies themselves. By probing the low-energy cosmic rays, low-frequency radio observations are especially interesting because they unveil emission powered by low-efficiency particle acceleration processes, which are believed to play a crucial role in the origin of diffuse radio emission. We investigate the origin of the radio mini-halo at the center of the galaxy cluster 2A0335+096 and its connection to the central galaxy and the sloshing cool core. We also study the properties of the head-tail galaxy GB6 B0335+096 hosted in the cluster to explore the lifecycle of the relativistic electrons in its radio tails. We use new LOw Frequency ARray (LOFAR) observations from the LOFAR Two-meter Sky Survey at 144MHz to map the low-frequency emission with a high level of detail. The new data were combined with archival Giant Metrewave Radio Telescope and Chandra observations to carry out a multi-wavelength study. We have made the first measurement of the spectral index of the mini-halo ({alpha}=-1.2+/-0.1 between 144MHz and 1.4GHz) and the lobes of the central source ({alpha}=~-1.5+/-0.1 between 144 and 610MHz). Based on the low-frequency radio emission morphology with respect to the thermal ICM, we propose that the origin of the diffuse radio emission is linked to the sloshing of the cool core. The new data revealed the presence of a Mpc-long radio tail associated with GB6 B0335+096. The observed projected length is a factor 3 longer than the expected cooling length, with evidence of flattening in the spectral index trend along the tail. Therefore, we suggest that the electrons toward the end of the tail are kept alive by the ICM gentle re-acceleration.
