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1511. SCUBA observations of cold cores
ID:
ivo://CDS.VizieR/J/MNRAS/368/1223
Title:
SCUBA observations of cold cores
Short Name:
J/MNRAS/368/1223
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the results of a submillimetre continuum emission survey targeted towards 78 star formation regions, 72 of which are devoid of methanol maser and UC HII regions, identified in the Swedish ESO Submillimetre Telescope (SEST)/SEST IMaging Bolometer Array (SIMBA) millimetre continuum survey of Hill et al. (2005, Cat. <J/MNRAS/363/405>). At least 45 per cent of the latter sources, dubbed 'mm-only', detected in this survey are also devoid of the mid-infrared MSX emission. The 450- and 850-um continuum emission was mapped using the Submillimetre Common User Bolometer Array (SCUBA) instrument on the James Clerk Maxwell Telescope (JCMT). Emission is detected towards 97 per cent of the 78 sources targeted as well as towards 28 other SIMBA sources lying in the SCUBA fields. In total, we have identified 212 cores in this submillimetre survey, including 106 previously known from the SIMBA survey. Of the remaining 106 sources, 53 result from resolving a SIMBA source into multiple submillimetre components, whilst the other 53 sources are submillimetre cores, not seen in the SIMBA. Additionally, we have identified two further mm-only sources in the SIMBA images. Of the total 405 sources identified in the SIMBA survey, 255 are only seen at millimetre wavelengths.
1512. SDSS AGN from ROSAT PSPC
ID:
ivo://CDS.VizieR/J/AJ/132/1475
Title:
SDSS AGN from ROSAT PSPC
Short Name:
J/AJ/132/1475
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a sample of 1744 type 1 active galactic nuclei (AGNs) from the Sloan Digital Sky Survey Data Release 4 (SDSS DR4) spectroscopic catalog with X-ray counterparts in the White-Giommi-Angelini Catalog (WGACAT) of ROSAT PSPC pointed observations. Of 1744 X-ray sources, 1410 (80.9%) are new AGN identifications. Of 4574 SDSS DR4 AGNs for which we found radio matches in the catalog of radio sources from the Faint Images of the Radio Sky at Twenty cm survey, 224 turned up in our sample of SDSS X-ray AGNs. The sample objects are given in a catalog that contains optical and X-ray parameters and supporting data, including redshifts; it also contains radio emission parameters where available. We illustrate the content of our catalog and its potential for AGN science by providing statistical relationships for the catalog data.
1513. SDSS-FIRST quasar sample study
ID:
ivo://CDS.VizieR/J/A+A/630/A110
Title:
SDSS-FIRST quasar sample study
Short Name:
J/A+A/630/A110
Date:
21 Oct 2021
Publisher:
CDS
Description:
When can an active galactic nucleus (AGN) be considered radio-loud? Following the established view of the AGNs inner workings, an AGN is radio-loud if associated with relativistic ejections emitting a radio synchrotron spectrum (i.e., it is a "jetted" AGN). In this paper we exploit the AGN main sequence that offers a powerful tool to contextualize radio properties. If large samples of optically-selected quasars are considered, AGNs are identified as radio-loud if their Kellermann's radio loudness ratio R_K_>10. Our aims are to characterize the optical properties of different classes based on radioloudness within the main sequence and to test whether the condition R_K_>10 is sufficient for the identification of RL AGNs, since the origin of relatively strong radio emission may not be necessarily due to relativistic ejection. A sample of 355 quasars was selected by cross-correlating the FIRST survey with the SDSS DR14 quasar catalog. We classified the optical spectra according to their spectral types along the main sequence of quasars. For each spectral type, we distinguished compact and extended morphology (providing a FIRST-based atlas of radio maps in the latter case), and three classes of radio-loudness: detected (specific flux ratio in the g band and at 1.4GHz, R_K'_<10), intermediate (10R_K'_<70), and radio loud (R_K'_>=70). The analysis revealed systematic differences between radio-detected (i.e., radio-quiet), radio-intermediate, and radio-loud in each spectral type along the main sequence. We show that spectral bins that contain the extreme Population A sources have radio power compatible with emission by mechanisms ultimately due to star formation processes. Radio-loud sources of Population B are characteristically jetted. Their broad H{beta} profiles can be interpreted as due to a binary broad-line region. We suggest that RL Population B sources should be preferential targets for the search of black hole binaries, and present a sample of binary black hole AGN candidates. The validity of the Kellermann's criterion may be dependent on the source location along the quasar main sequence. The consideration of the MS trends allowed to distinguish between sources whose radio emission mechanisms is "jetted" from the ones where the mechanism is likely to be fundamentally different.
1514. SDSS search for binary AGN
ID:
ivo://CDS.VizieR/J/ApJ/716/866
Title:
SDSS search for binary AGN
Short Name:
J/ApJ/716/866
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present active galactic nuclei (AGNs) from the Sloan Digital Sky Survey (SDSS) having double-peaked profiles of [OIII]5007,4959 and other narrow emission lines, motivated by the prospect of finding candidate binary AGNs. These objects were identified by means of a visual examination of 21592 quasars at z<0.7 in SDSS Data Release 7 (DR7). Of the spectra with adequate signal-to-noise, 148 spectra exhibit a double-peaked [OIII] profile. Of these, 86 are Type 1 AGNs and 62 are Type 2 AGNs. Only two give the appearance of possibly being optically resolved double AGNs in the SDSS images, but many show close companions or signs of recent interaction. Radio-detected quasars are three times more likely to exhibit a double-peaked [OIII] profile than quasars with no detected radio flux, suggesting a role for jet interactions in producing the double-peaked profiles. Of the 66 broad-line (Type 1) AGNs that are undetected in the FIRST survey, 0.9% show double-peaked [OIII] profiles.
1515. SDSS Stripe 82 VLA 1-2GHz survey
ID:
ivo://CDS.VizieR/J/MNRAS/460/4433
Title:
SDSS Stripe 82 VLA 1-2GHz survey
Short Name:
J/MNRAS/460/4433
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have used the Karl G. Jansky Very Large Array to image ~100deg^2^ of SDSS Stripe 82 at 1-2GHz. The survey consists of 1026 snapshot observations of 2.5-min duration, using the hybrid CnB configuration. The survey has good sensitivity to diffuse, low surface brightness structures and extended radio emission, making it highly synergistic with existing 1.4GHz radio observations of the region. The principal data products are continuum images, with 16x10 arcsec resolution, and a catalogue containing 11782 point and Gaussian components resulting from fits to the thresholded Stokes-I brightness distribution, forming approximately 8948 unique radio sources. The typical effective 1{sigma} noise level is 88{mu}Jy/beam. Spectral index estimates are included, as derived from the 1GHz of instantaneous bandwidth. Astrometric and photometric accuracy are in excellent agreement with existing narrowband observations. A large-scale simulation is used to investigate clean bias, which we extend into the spectral domain. Clean bias remains an issue for snapshot surveys with the VLA, affecting our total intensity measurements at the ~1{sigma} level. Statistical spectral index measurements are in good agreement with existing measurements derived from matching separate surveys at two frequencies. At flux densities below ~35{sigma} the median in-band spectral index measurements begin to exhibit a bias towards flatness that is dependent on both flux density and the intrinsic spectral index. In-band spectral curvature measurements are likely to be unreliable for all but the very brightest components. Image products and catalogues are publicly available via an FTP server (ftp://ftp.atnf.csiro.au/pub/people/hey036/Stripe82).
1516. SDSS/3XMM X-ray-selected LINERs
ID:
ivo://CDS.VizieR/J/MNRAS/455/2551
Title:
SDSS/3XMM X-ray-selected LINERs
Short Name:
J/MNRAS/455/2551
Date:
21 Oct 2021
Publisher:
CDS
Description:
A sample of 576 X-ray-selected LINERs was constructed by combining data from the 3XMM-DR4 and SDSS-DR7 catalogues. The sample was used to investigate the fraction of galaxies hosting a LINER, finding that the fraction is a strong function of both stellar mass and black hole mass (increasing as f_LINER_{prop.to}M*^1.6+/-0.2^ and f_LINER_{propto}M_BH_^0.6+/-0.1^, respectively) and that it rises close to unity at the highest black hole masses and lowest X-ray luminosities. After obtaining radio flux densities from the FIRST survey, the sample was also used to investigate the Fundamental Plane of black hole activity - a scale-invariant relationship between black hole mass, X-ray luminosity and radio luminosity that is believed to hold across at least nine orders of magnitude of mass. There are key advantages in using only LINERs for the derivation as these are the counterparts of the 'low-hard' X-ray binaries for which the relationship is tightest. The Fundamental Plane was found to be log(L_R_/(erg/s)) = 0.65(+/-0.07)log(L_X_/(10^42^erg/s)) + 0.69(+/-0.10)log(M_BH_/10^8^M_{sun}_) + 38.35(+/-0.10). The scatter around the plane was 0.73+/-0.03dex, too large to suggest that the Fundamental Plane can be used as a tool to estimate black hole mass from the observables of X-ray and radio luminosity. The black hole mass scaling is sensitive to the slope of the mass - velocity dispersion relation and, in order to achieve consistency with X-ray binaries, the analysis favours a steep gradient for this relationship, as found in recent research.
1517. Search for extraterrestrial intelligence with ATA
ID:
ivo://CDS.VizieR/J/ApJ/869/66
Title:
Search for extraterrestrial intelligence with ATA
Short Name:
J/ApJ/869/66
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report a novel radio autocorrelation search for extraterrestrial intelligence. For selected frequencies across the terrestrial microwave window (1-10GHz), observations were conducted at the Allen Telescope Array to identify artificial non-sinusoidal periodic signals with radio bandwidths greater than 4Hz, which are capable of carrying substantial messages with symbol rates from 4 to 10^6^Hz. Out of 243 observations, about half (101) were directed toward sources with known continuum flux >~1Jy over the sampled bandwidth (quasars, pulsars, supernova remnants, and masers), based on the hypothesis that they might harbor heretofore undiscovered natural or artificial repetitive, phase or frequency modulation. The rest of the observations were directed mostly toward exoplanet stars with no previously discovered continuum flux. No signals attributable to extraterrestrial technology were found in this study. We conclude that the maximum probability that future observations like the ones described here will reveal repetitively modulated emissions is less than 5% for continuum sources and exoplanets alike. The paper concludes by describing a new approach to expanding this survey to many more targets and much greater sensitivity using archived data from interferometers all over the world.
1518. Search for megamasers in type-2 AGNs
ID:
ivo://CDS.VizieR/J/ApJ/695/276
Title:
Search for megamasers in type-2 AGNs
Short Name:
J/ApJ/695/276
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report a search for H_2_O megamasers in 274 SDSS type-2 active galactic nuclei (AGNs; 0.3<z<0.83), half of which can be classified as type-2 quasi-stellar objects (QSOs) from their [OIII]5007 luminosity, using the Robert C. Byrd Green Bank Telescope (GBT) and the Effelsberg 100m radio telescope. Apart from the detection of the extremely luminous water vapor megamaser SDSS J080430.99+360718.1, already reported by Barvainis & Antonucci (2005ApJ...628...89B), we do not find any additional line emission. This high rate of nondetections is compared to the water maser luminosity function created from the 78 water maser galaxies known to date and its extrapolation toward the higher luminosities of "gigamasers" that we would have been able to detect given the sensitivity of our survey. The properties of the known water masers are summarized and discussed with respect to the nature of high-z type-2 AGNs and megamasers in general. In the Appendix (tables 4 and 5), we list 173 additional objects (mainly radio galaxies, but also QSOs and galaxies) that were observed with the GBT, the Effelsberg 100m radio telescope, or Arecibo Observatory without leading to the detection of water maser emission.
1519. Search for OH maser emission
ID:
ivo://CDS.VizieR/J/A+AS/119/459
Title:
Search for OH maser emission
Short Name:
J/A+AS/119/459
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a survey for OH maser emission at 18cm in the direction of 196 IRAS point sources. The primary aim of the survey was to detect OH maser emission from post-asymptotic giant branch (post-AGB) stars. OH emission and/or absorption was detected in the direction of 77 sources of which 57 OH detections were previously unknown, giving an overall detection rate of 39 per cent. Fourteen maser sources associated with evolved stars or planetary nebulae were found, corresponding to 7 per cent of the total observed. These included three planetary nebulae (two new OH detections), nine post-AGB stars (three new OH detections) and two cold OH/IR stars (both previously known). Two sources were of uncertain identification (both new OH detections). The remainder of the OH sources were identified with young stellar objects and with HII regions. The survey included the detection of OH maser emission from HD 101584, an early-type supergiant at high Galactic latitude. For several of the post-AGB stars, changes have occurred in the OH spectral profiles over a period of several years. This is interpreted as evidence for rapid changes in the stellar winds, due either to interactions with stellar companions, novae-like events or rapid stellar evolution.
1520. Search for radio emission from giant exoplanets
ID:
ivo://CDS.VizieR/VI/151
Title:
Search for radio emission from giant exoplanets
Short Name:
VI/151
Date:
21 Oct 2021
Publisher:
CDS
Description:
The intensity of Jupiter's auroral radio emission quickly gave rise to the question whether a comparable coherent emission from the magnetosphere of an exoplanet could be detectable. An exoplanetary radio emission would have to be at least 1000 times more intense than Jupiter's emission to be detectable with current radio telescopes. Theoretical models suggest that, at least in certain cases, the radio emission of giant exoplanets may indeed reach the required intensity. At the same time, in order to generate such an emission, an exoplanet would have to have a sufficiently strong intrinsic planetary magnetic field. Extrasolar planets are indeed expected to have a planetary magnetic field, but to date, their magnetic field has never been detected. We will show that the most promising technique to observe exoplanetary magnetic fields is indeed to search for the planetary auroral radio emission. The detection of such an emission would thus constitute the first unambiguous detection of an exoplanetary magnetic field. We will review recent theoretical studies and discuss their results for the two main parameters, namely the maximum emission frequency and the intensity of the radio emission. The predicted values should allow the detection using modern low-frequency radio telescopes. We will present an ongoing observation program with the Low Frequency Array (LOFAR), which has the potential to detect exoplanetary radio emission.