- ID:
- ivo://CDS.VizieR/J/ApJS/123/219
- Title:
- Planetary Nebulae in NRAO VLA Sky Survey
- Short Name:
- J/ApJS/123/219
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In order to construct a sample of planetary nebulae (PNe) unbiased by dust extinction, we first selected the 1358 sources in the IRAS Point Source Catalog north of J2000 declination DE=-40{deg} having measured S(25{mu}m)>=1 Jy and colors characteristic of PNe: detections or upper limits consistent with both S(12{mu}m)<=0.35S(25{mu}m) and S(25{mu}m)>=0.35S(60{mu}m). The majority are radio-quiet contaminating sources such as asymptotic giant branch stars. Free-free emission from genuine PNe should make them radio sources. The 1.4 GHz NRAO VLA Sky Survey (NVSS) images and source catalog were used to reject radio-quiet mid-infrared sources. We identified 454 IRAS sources with radio sources brighter than S~2.5 mJy/beam (equivalent to T~0.8K in the 45" FHWM NVSS beam) by positional coincidence. They comprise 332 known PNe in the Strasbourg-ESO Catalogue of Galactic Planetary Nebulae and 122 candidate PNe, most of which lie at very low Galactic latitudes. Exploratory optical spectroscopic observations suggest that most of these candidates are indeed PNe optically dimmed by dust extinction, although some contamination remains from H II regions, Seyfert galaxies, etc. Furthermore, the NVSS failed to detect only 4% of the known PNe in our infrared sample. Thus it appears that radio selection can greatly improve the reliability of PN candidate samples without sacrificing completeness.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/548/A106
- Title:
- PMN J0948+0022 radio-to-gamma-ray monitoring
- Short Name:
- J/A+A/548/A106
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present more than three years of observations at different frequencies, from radio to high-energy gamma-rays, of the Narrow-Line Seyfert 1 (NLS1) Galaxy PMN J0948+0022 (z=0.585). This source is the first NLS1 detected at energies above 100 MeV and therefore can be considered the prototype of this emerging new class of gamma-ray emitting active galactic nuclei (AGN). The observations performed from 2008 August 1 to 2011 December 31 confirmed that PMN J0948+0022 generates a powerful relativistic jet, able to develop an isotropic luminosity at gamma-rays of the order of 10^48^erg/s, at the level of powerful quasars. The evolution of the radiation emission of this source in 2009 and 2010 followed the canonical expectations of relativistic jets, with correlated multiwavelength variability (gamma-rays followed by radio emission after a few months), but it was difficult to retrieve a similar pattern in the light curves of 2011. The comparison of gamma-ray spectra before and including 2011 data suggested that there was a softening of the high-energy spectral slope. We selected five specific epochs to be studied by modelling the broad-band spectrum, characterised by an outburst at gamma-rays or very low/high flux at other wavelengths. The observed variability can largely be explained either by changes in the injected power, the bulk Lorentz factor of the jet or the electron spectrum. The characteristic time scale of doubling/halving flux ranges from a few days to a few months, depending on the frequency and the sampling rate. The shortest doubling time scale at gamma-rays is 2.3+/-0.5days. These small values underline the need of highly-sampled multiwavelength campaigns to better understand the physics of these sources.
- ID:
- ivo://CDS.VizieR/J/ApJS/90/173
- Title:
- PMN map catalog of radiosources
- Short Name:
- J/ApJS/90/173
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Parkes-MIT-NRAO (PMN) southern survey was made with the NRAO 4.85GHz seven-beam receiver on the Parkes 64 m telescope during 1990 June, and maps covering the Omega = 2.5 sr declination band -88{deg}<Dec.<-37{deg} were constructed from the survey scans. We present a catalog of 15,045 discrete sources with angular sizes phi<~15arcmin and stronger than S~25mJy derived from these maps. Machine-readable versions of the catalog with either B1950 or J2000 positions, and a printed catalog with B1950 positions only, are available. The 4.85GHz weighted source counts S^(5/2)^n(S) between 30mJy and 10Jy were obtained and agree well with previous results.
- ID:
- ivo://CDS.VizieR/J/A+A/631/A74
- Title:
- POETS luminous YSOs 13 or 22GHz images
- Short Name:
- J/A+A/631/A74
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Although recent observations and theoretical simulations have pointed out that accretion disks and jets can be essential for the formation of stars with a mass of up to at least 20M_{sun}_, the processes regulating mass accretion and ejection are still uncertain. The goal of the Protostellar Outflows at the EarliesT Stages (POETS) survey is to image the disk-outflow interface on scales of 10-100au in a statistically significant sample (36) of luminous young stellar objects (YSO), targeting both the molecular and ionized components of the outflows. The outflow kinematics is studied at milliarcsecond scales through very long baseline interferometry (VLBI) observations of the 22GHz water masers, which are ideal test particles to measure the three-dimensional (3D) motion of shocks owing to the interaction of winds and jets with ambient gas. We employed the Jansky Very Large Array (JVLA) at 6, 13, and 22GHz in the Aand B-Array configurations to determine the spatial structure and the spectral index of the radio continuum emission, and address its nature. In about half of the targets, the water masers observed at separation <=1000au from the YSOs trace either or both of these kinematic structures: 1) a spatially elongated distribution oriented at close angle with the direction of collimation of the maser proper motions (PM), and 2) a linear local standard of rest (LSR) velocity (VLSR) gradient across the YSO position. The kinematic structure (1) is readily interpreted in terms of a protostellar jet, as confirmed in some targets via the comparison with independent observations of the YSO jets, in thermal (continuum and line) emissions, reported in the literature. The kinematic structure (2) is interpreted in terms of a disk-wind (DW) seen almost edge-on on the basis of several pieces of evidence: first, it is invariably directed perpendicular to the YSO jet; second, it agrees in orientation and polarity with the VLSR gradient in thermal emissions (when reported in the literature) identifying the YSO disk at scales of <=1000au; third, the PMs of the masers delineating the VLSR gradients hint at flow motions at a speed of 10-20km/s directed at large angles with the disk midplane. In the remaining targets, the maser PMs are not collimated but rather tend to align along two almost perpendicular directions. To explain this peculiar PM distribution, and in light of the observational bias strongly favoring masers moving close to the plane of sky, we propose that, in these sources, the maser emission could originate in DW-jet systems slightly inclined (<=30{deg}) with respect to edge-on. Magneto-centrifugally driven DWs could in general account for the observed velocity patterns of water masers.
- ID:
- ivo://CDS.VizieR/J/other/Ser/189.15
- Title:
- Point source catalogue of M31. DR2
- Short Name:
- J/other/Ser/189.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Data Release 2 of the Point Source Catalogue created from a series of previously constructed radio-continuum images of M31 at lambda=20cm (nu=1.4GHz) from archived VLA observations. In total, we identify a collection of 916 unique discrete radio sources across the field of M31. Comparing these detected sources to those listed by Gelfand et al. (<A HREF="http://simbad.cds.unistra.fr/simbad/sim-ref?bibcode=2004ApJS..155...89G%202004ApJS..155...89G">2004ApJS..155...89G 2004ApJS..155...89G</A>, Cat. <A HREF="http://cdsarc.u-strasbg.fr/cgi-bin/Cat?J/ApJS/155/89">J/ApJS/155/89</A>) at lambda=92cm, the spectral index of 98 sources has been derived. The majority (73%) of these sources exhibit a spectral index of α←0.6, indicating that their emission is predominantly non-thermal in nature, which is typical for background objects and Supernova Remnants (SNRs).
- ID:
- ivo://CDS.VizieR/J/MNRAS/474/4629
- Title:
- Polarimetry of 600 pulsars from 1.4GHz obs.
- Short Name:
- J/MNRAS/474/4629
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Over the past 13yr, the Parkes radio telescope has observed a large number of pulsars using digital filter bank backends with high time and frequency resolution and the capability for Stokes recording. Here, we use archival data to present polarimetry data at an observing frequency of 1.4GHz for 600 pulsars with spin-periods ranging from 0.036 to 8.5s. We comment briefly on some of the statistical implications from the data and highlight the differences between pulsars with high and low spin-down energy. The data set, images and table of properties for all 600 pulsars are made available in a public data archive maintained by the CSIRO.
- ID:
- ivo://CDS.VizieR/J/MNRAS/376/371
- Title:
- Polarisation of flat-spectrum radio sources
- Short Name:
- J/MNRAS/376/371
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used the very large JVAS/CLASS 8.4GHz surveys of flat-spectrum radio sources to obtain a large, uniformly observed and calibrated, sample of radio source polarizations. These are useful for many investigations of the properties of radio sources and the interstellar medium. We discuss comparisons with polarization measurements from this survey and from other large-scale surveys of polarization in flat-spectrum sources.
- ID:
- ivo://CDS.VizieR/J/AJ/87/859
- Title:
- Polarisation of 404 radio sources at 6 and 20cm
- Short Name:
- J/AJ/87/859
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Accurate positions of 404 compact radio sources used as calibrators by the VLA are presented. In addition, the structure and polarization of each source at both 4885 and 1465MHz are given. Eighty-five percent of the sources have spectral indices flatter than 0.5; all of these are dominated by an unresolved core. Half of these flat-spectrum sources contain nearby, associated diffuse structure at a level exceeding approximately 0.4% of the core brightness at 20cm.
- ID:
- ivo://CDS.VizieR/J/MNRAS/360/1305
- Title:
- Polarization of extragalactic sources
- Short Name:
- J/MNRAS/360/1305
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have observed a sample of 64 small-diameter sources towards the central -6<l<6, -2<b<2 of the Galaxy with the aim of studying the Faraday rotation measure near the Galactic Centre region. All the sources were observed at 6- and 3.6-cm wavelengths using the ATCA and the VLA. 59 of these sources are inferred to be extragalactic. The observations presented here constitute the first systematic study of the radio polarization properties of the background sources towards this direction and increase the number of known extragalactic radio sources in this part of the sky by almost an order of magnitude. Based on the morphology, spectral indices and lack of polarized emission, we identify four Galactic HII regions in the sample.
- ID:
- ivo://CDS.VizieR/J/ApJS/212/15
- Title:
- Polarized NVSS sources SEDs
- Short Name:
- J/ApJS/212/15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An understanding of cosmic magnetism requires converting the polarization properties of extragalactic radio sources into the rest-frame in which the corresponding polarized emission or Faraday rotation is produced. Motivated by this requirement, we present a catalog of multiwavelength linear polarization and total intensity radio data for polarized sources from the NRAO VLA Sky Survey. We cross-match these sources with a number of complementary measurements --combining data from major radio polarization and total intensity surveys such as AT20G, B3-VLA, GB6, NORTH6CM, Texas, and WENSS, together with other polarization data published over the last 50 years. For 951 sources, we present spectral energy distributions (SEDs) in both fractional polarization and total intensity, each containing between 3 and 56 independent measurements from 400MHz to 100GHz. We physically model these SEDs, and where available provide the redshift of the optical counterpart. For a superset of 25649 sources we provide the total intensity spectral index, {alpha}. Objects with steep versus flat {alpha} generally have different polarization SEDs: steep-spectrum sources exhibit depolarization, while flat-spectrum sources maintain constant polarized fractions over large ranges in wavelength. This suggests the run of polarized fraction with wavelength is predominantly affected by the local source environment, rather than by unrelated foreground magnetoionic material. In addition, a significant fraction (21%) of sources exhibit "repolarization," which further suggests that polarized SEDs are affected by different emitting regions within the source, rather than by a particular depolarization law. This has implications for the physical interpretation of future broadband polarimetric surveys.
