- ID:
- ivo://CDS.VizieR/J/A+A/644/A85
- Title:
- Sub-milliarcsecond imaging of 3C111
- Short Name:
- J/A+A/644/A85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Flares in radio-loud active galactic nuclei (AGNs) are thought to be associated with the injection of fresh plasma into the compact jet base. Such flares are usually strongest and appear earlier at shorter radio wavelengths. Hence, very long baseline interferometry (VLBI) at millimeter (mm)-wavelengths is the best-suited technique for studying the earliest structural changes of compact jets associated with emission flares. Aims. We study the morphological changes of the parsec-scale jet in the nearby (z=0.049) gamma-ray bright radio galaxy 3C 111 following a flare that developed into a major radio outburst in 2007. We analyse three successive observations of 3C 111 at 86 GHz with the Global mm-VLBI Array (GMVA) between 2007 and 2008 which yield a very high angular resolution of ~45 muas. In addition, we make use of single-dish radio flux density measurements from the F-GAMMA and POLAMI programmes, archival single-dish and VLBI data. We resolve the flare into multiple plasma components with a distinct morphology resembling a bend in an otherwise remarkably straight jet. The flare-associated features move with apparent velocities of ~4.0c to ~4.5c and can be traced also at lower frequencies in later epochs. Near the base of the jet, we find two bright features with high brightness temperatures up to ~10^11^K, which we associate with the core and a stationary feature in the jet. The flare led to multiple new jet components indicative of a dynamic modulation during the ejection. We interpret the bend-like feature as a direct result of the outburst which makes it possible to trace the transverse structure of the jet. In this scenario, the components follow different paths in the jet stream consistent with expectations for a spine-sheath structure, which is not seen during intermediate levels of activity. The possibility of coordinated multiwavelength observations during a future bright radio flare in 3C 111 makes this source an excellent target for probing the radio-gamma-ray connection.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/543/A161
- Title:
- Submillimetre obs. of 323 HRS nearby galaxies
- Short Name:
- J/A+A/543/A161
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Herschel Reference Survey (HRS) is a guaranteed time Herschel key project aimed at studying the physical properties of the interstellar medium in galaxies of the nearby universe. This volume limited, K-band selected sample is composed of galaxies spanning the whole range of morphological types (from ellipticals to late-type spirals) and environments (from the field to the centre of the Virgo Cluster). We present flux density measurements of the whole sample of 323 galaxies of the HRS in the three bands of the Spectral and Photometric Imaging Receiver (SPIRE), at 250um, 350um and 500um. Aperture photometry is performed on extended galaxies and point spread function (PSF) fitting on timeline data for unresolved objects; we carefully estimate errors and upper limits. The flux densities are found to be in good agreement with those of the HeViCS and KINGFISH key projects in all SPIRE bands, and of the Planck consortium at 350um and 550um, for the galaxies in common. This submillimetre catalogue of nearby galaxies is a benchmark for the study of the dust properties in the local universe, giving the zero redshift reference for any cosmological survey.
- ID:
- ivo://CDS.VizieR/J/MNRAS/411/505
- Title:
- Sub-mm observations in Extended Chandra DFS
- Short Name:
- J/MNRAS/411/505
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a joint analysis of the overlapping Balloon-borne Large Aperture Submillimetre Telescope (BLAST) 250, 350, 500um, and LABOCA 870um observations [from the LABOCA ECDFS Submm Survey (LESS) survey] of the Extended Chandra Deep Field-South. Out to z~3, the BLAST filters sample near the peak wavelength of thermal far-infrared (FIR) emission from galaxies (rest-frame wavelengths ~60-200um), primarily produced by dust heated through absorption in star-forming clouds. However, identifying counterparts to individual BLAST peaks is very challenging, given the large beams [full-width at half-maximum (FWHM) 36-60 arcsec]. In contrast, the ground-based 870um observations have a significantly smaller 19 arcsec FWHM beam, and are sensitive to higher redshifts (z~1-5, and potentially beyond) due to the more favourable negative K-correction. We use the LESS data, as well as deep Spitzer and VLA imaging, to identify 118 individual sources that produce significant emission in the BLAST bands.
- ID:
- ivo://CDS.VizieR/J/A+A/579/A115
- Title:
- SUDARE-VOICE variability-selection of AGN
- Short Name:
- J/A+A/579/A115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- One of the most peculiar characteristics of active galactic nuclei (AGNs) is their variability over all wavelengths. This property has been used in the past to select AGN samples and is foreseen to be one of the detection techniques applied in future multi-epoch surveys, complementing photometric and spectroscopic methods. In this paper, we aim to construct and characterise an AGN sample using a multi-epoch dataset in the r band from the SUDARE-VOICE survey. Our work makes use of the VST monitoring programme of an area surrounding the Chandra Deep Field South to select variable sources. We use data spanning a six-month period over an area of 2 square degrees, to identify AGN based on their photometric variability. The selected sample includes 175 AGN candidates with magnitude r<23mag. We distinguish different classes of variable sources through their lightcurves, as well as X-ray, spectroscopic, SED, optical, and IR information overlapping with our survey. We find that 12% of the sample (21/175) is represented by supernovae (SN). Of the remaining sources, 4% (6/154) are stars, while 66% (102/154) are likely AGNs based on the available diagnostics. We estimate an upper limit to the contamination of the variability selected AGN sample =~34%, but we point out that restricting the analysis to the sources with available multi-wavelength ancillary information, the purity of our sample is close to 80% (102 AGN out of 128 non-SN sources with multi-wavelength diagnostics). Our work thus confirms the efficiency of the variability selection method, in agreement with our previous work on the COSMOS field. In addition we show that the variability approach is roughly consistent with the infrared selection.
- ID:
- ivo://CDS.VizieR/J/A+A/580/A129
- Title:
- Sulphur in the Sculptor dSph
- Short Name:
- J/A+A/580/A129
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In Galactic halo stars, sulphur has been shown to behave like other {alpha}-elements, but until now, no comprehensive studies have been done on this element in stars of other galaxies. Here, we use high-resolution ESO VLT/FLAMES/GIRAFFE spectra to determine sulphur abundances for 85 stars in the Sculptor dwarf spheroidal galaxy, covering the metallicity range -2.5<=[Fe/H]<=-0.8. The abundances are derived from the SI triplet at 9213, 9228, and 9238{AA}. These lines have been shown to be sensitive to departure from local thermodynamic equilibrium, i.e. NLTE effects. Therefore, we present new NLTE corrections for a grid of stellar parameters covering those of the target stars. The NLTE-corrected sulphur abundances in Sculptor show the same behaviour as other {alpha}-elements in that galaxy (such as Mg, Si, and Ca). At lower metallicities ([Fe/H]<~-2) the abundances are consistent with a plateau at [S/Fe]=~+0.16, similar to what is observed in the Galactic halo, [S/Fe]=~+0.2. With increasing [Fe/H], the [S/Fe] ratio declines, reaching negative values at [Fe/H]>-1.5. The sample also shows an increase in [S/Mg] with [Fe/H], most probably because of enrichment from Type Ia supernovae.
3656. SUMaC I
- ID:
- ivo://CDS.VizieR/J/MNRAS/466/4540
- Title:
- SUMaC I
- Short Name:
- J/MNRAS/466/4540
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first results from the Swift Ultraviolet Survey of the Magellanic Clouds, the highest resolution ultraviolet (UV) survey of the Magellanic Clouds yet completed. In this paper, we focus on the Small Magellanic Cloud (SMC). When combined with multiwavelength optical and infrared observations, the three near-UV filters on the Swift Ultraviolet/Optical Telescope are conducive to measuring the shape of the dust extinction curve and the strength of the 2175{AA} dust bump. We divide the SMC into UV-detected star-forming regions and large 200-arcsec (58pc) pixels and then model the spectral energy distributions using a Markov-chain Monte Carlo method to constrain the ages, masses, and dust curve properties. We find that the majority of the SMC has a 2175{AA} dust bump, which is larger to the north-east and smaller to the south-west, and that the extinction curve is predominantly steeper than the Galactic curve. We also derive a star formation history and find evidence for peaks in the star formation rate at 6-10, 30-80, and 400Myr, the latter two of which are consistent with previous work.
- ID:
- ivo://CDS.VizieR/J/AJ/122/2222
- Title:
- Superclusters of Abell and X-ray clusters
- Short Name:
- J/AJ/122/2222
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new catalog of superclusters of Abell clusters out to a redshift of z_lim_=0.13, a catalog of X-ray clusters located in superclusters determined by Abell clusters, and a list of additional superclusters of X-ray clusters. We investigate the distribution of X-ray selected clusters of galaxies with respect to superclusters determined by Abell clusters of galaxies and show that the distribution of X-ray clusters follows the supercluster-void network determined by Abell clusters. We find that X-ray clusters are more strongly clustered than other clusters: the fraction of X-ray clusters is higher in rich superclusters, and the fraction of isolated X-ray clusters is lower than the fraction of isolated Abell clusters. Poor, non-Abell X-ray clusters follow the supercluster-void network as well: these clusters are embedded in superclusters determined by Abell clusters and populate filaments between them. This catalogue supersedes J/A+AS/123/119
- ID:
- ivo://CDS.VizieR/J/ApJ/853/172
- Title:
- "Super-deblended" dust emission in galaxies. I.
- Short Name:
- J/ApJ/853/172
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new technique to measure multi-wavelength "super-deblended" photometry from highly confused images, which we apply to Herschel and ground-based far-infrared (FIR) and (sub-)millimeter (mm) data in the northern field of the Great Observatories Origins Deep Survey (GOODS-N). There are two key novelties. First, starting with a large database of deep Spitzer 24{mu}m and VLA 20cm detections that are used to define prior positions for fitting the FIR/submm data, we perform an active selection of useful priors independently at each frequency band, moving from less to more confused bands. Exploiting knowledge of redshift and all available photometry, we identify hopelessly faint priors that we remove from the fitting pool. This approach significantly reduces blending degeneracies and allows reliable photometry to be obtained for galaxies in FIR+mm bands. Second, we obtain well-behaved, nearly Gaussian flux density uncertainties, individually tailored to all fitted priors for each band. This is done by exploiting extensive simulations that allow us to calibrate the conversion of formal fitting uncertainties to realistic uncertainties, depending on directly measurable quantities. We achieve deeper detection limits with high fidelity measurements and uncertainties at FIR+mm bands. As an illustration of the utility of these measurements, we identify 70 galaxies with z>=3 and reliable FIR+mm detections. We present new constraints on the cosmic star formation rate density at 3<z<6, finding a significant contribution from z>=3 dusty galaxies that are missed by optical-to-near-infrared color selection. Photometric measurements for 3306 priors, including more than 1000 FIR+mm detections, are released publicly with our catalog.
- ID:
- ivo://CDS.VizieR/J/ApJS/75/241
- Title:
- Supergalactic plane redshift survey
- Short Name:
- J/ApJS/75/241
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Redshift measurements, about 1000 of which are new, are presented for 1314 galaxies in a survey toward the apex of the large-scale streaming flow for ellipticals.
- ID:
- ivo://CDS.VizieR/J/ApJ/599/1049
- Title:
- Supergiant molecular complexes in the Antennae
- Short Name:
- J/ApJ/599/1049
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used previously published observations of the CO emission from the Antennae (NGC 4038/4039) to study the detailed properties of the supergiant molecular complexes with the goal of understanding the formation of young massive star clusters.
