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301. Giant radio quasars from SDSS, FIRST & NVSS
ID:
ivo://CDS.VizieR/J/ApJS/253/25
Title:
Giant radio quasars from SDSS, FIRST & NVSS
Short Name:
J/ApJS/253/25
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the largest sample of giant radio quasars (GRQs), which are defined as having a projected linear size greater than 0.7Mpc. The sample consists of 272 GRQs, of which 174 are new objects discovered through cross-matching the NRAO Very Large Array Sky Survey and the Sloan Digital Sky Survey 14th Data Release Quasar Catalog (DR14Q) and confirmed using Faint Images of the Radio Sky at Twenty-Centimeters (FIRST) radio maps. In our analysis we compare the GRQs with 367 smaller, lobe-dominated radio quasars found using our search method, as well as with quasars from the SDSS DR14Q, investigating the parameters characterizing their radio emission (i.e., total and core radio luminosity, radio core prominence), optical properties (black hole masses, accretion rates, distribution in Eigenvector 1 plane) and infrared colors. For the GRQs and smaller radio quasars we find a strong correlation between [OIII] luminosity and radio luminosity at 1.4GHz, indicating a strong connection between radio emission and conditions in the narrow-line region. We spot no significant differences between GRQs and smaller radio quasars, however we show that most extended radio quasars belong to a quasar population of evolved active galactic nuclei with large black hole masses and low accretion rates. We also show that GRQs have bluer W2-W3 colors compared to SDSS quasars with FIRST detections, indicating differences in the structure of the dusty torus.
302. Giant Radio Quasars properties
ID:
ivo://CDS.VizieR/J/MNRAS/426/851
Title:
Giant Radio Quasars properties
Short Name:
J/MNRAS/426/851
Date:
21 Oct 2021
Publisher:
CDS
Description:
We analysed the optical and radio properties of lobe-dominated giant-sized (>0.72Mpc) radio quasars and compared the results with those derived for a sample of smaller radio sources to determine whether the large size of some extragalactic radio sources is related to the properties of their nuclei. We compiled the largest (to date) sample of giant radio quasars, including 24 new and 21 previously known objects, and calculated a number of important parameters of their nuclei such as the black hole mass and the accretion rate.
303. Globular clusters as gravitational lenses
ID:
ivo://CDS.VizieR/J/PAZh/33/403
Title:
Globular clusters as gravitational lenses
Short Name:
J/PAZh/33/403
Date:
21 Oct 2021
Publisher:
CDS
Description:
Based on the SDSS catalog, we have found new close quasar-galaxy pairs. We analyze the radial distribution of quasars from pairs around galaxies of different types. We show that the quasars from pairs follow the density profile of halo globular clusters. This is new observational evidence that the quasars projected onto the halos of galaxies are magnified by gravitational lensing by halo globular clusters.
304. GPS radio sources multifrequency study
ID:
ivo://CDS.VizieR/J/A+A/544/A25
Title:
GPS radio sources multifrequency study
Short Name:
J/A+A/544/A25
Date:
21 Oct 2021
Publisher:
CDS
Description:
Gigahertz peaked spectrum (GPS) radio sources are a class of extragalactic radio sources characterized by a spectral peak in the gigahertz domain. They are a mixed class of quasars and galaxies. A large proportion of the sources studied in the literature have only few data points in the radio domain, and the determination of variability and shape of the simultaneous spectra is inadequate. Sources currently included in the GPS source lists are very heterogeneous. We present the observational results from 12 observing campaigns (carried out between 2006 and 2010) at the RATAN-600 radio telescope to obtain the simultaneous radio spectra, which is valuable and necessary to derive genuine GPS sources from flat-spectrum radio sources caught in a flaring state when their spectra are temporarily inverted. The sample contains both quasar- and galaxy-type GPS (122 sources) identified in the literature.
305. Gravitational lenses among z>=4.0 quasars
ID:
ivo://CDS.VizieR/J/AJ/131/49
Title:
Gravitational lenses among z>=4.0 quasars
Short Name:
J/AJ/131/49
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report on i-band snapshot observations of 157 Sloan Digital Sky Survey quasars at 4.0<z<5.4 using the Advanced Camera for Surveys on the Hubble Space Telescope (HST) to search for evidence of gravitational lensing of these sources.
306. Gravitationally Lensed Quasars
ID:
ivo://CDS.VizieR/J/ApJ/409/28
Title:
Gravitationally Lensed Quasars
Short Name:
J/ApJ/409/28
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Snapshot Survey was a search for cases of gravitational lensing among intrinsically-luminous, high-redshift quasars using the Hubble Space Telescope (HST) Planetary Camera (PC). The accompanying ASCII tables summarize the results of the survey.
307. Gravitationally lensed quasars
ID:
ivo://CDS.VizieR/J/MNRAS/458/2
Title:
Gravitationally lensed quasars
Short Name:
J/MNRAS/458/2
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of an imaging observation campaign conducted with the Subaru Telescope adaptive optics system (IRCS+AO188) on 28 gravitationally lensed quasars and candidates (23 doubles, 1 quad, 1 possible triple, and 3 candidates) from the SDSS Quasar Lens Search. We develop a novel modelling technique that fits analytical and hybrid point spread functions (PSFs), while simultaneously measuring the relative astrometry, photometry, as well as the lens galaxy morphology. We account for systematics by simulating the observed systems using separately observed PSF stars. The measured relative astrometry is comparable with that typically achieved with the Hubble Space Telescope, even after marginalizing over the PSF uncertainty. We model for the first time the quasar host galaxies in five systems, without a priori knowledge of the PSF, and show that their luminosities follow the known correlation with the mass of the supermassive black hole. For each system, we obtain mass models far more accurate than those previously published from low-resolution data, and we show that in our sample of lensing galaxies the observed light profile is more elliptical than the mass, for ellipticity >~0.25. We also identify eight doubles for which the sources of external and internal shear are more reliably separated, and should therefore be prioritized in monitoring campaigns aimed at measuring time delays in order to infer the Hubble constant.
308. griz light curves of 15 DES quasars
ID:
ivo://CDS.VizieR/J/ApJ/862/123
Title:
griz light curves of 15 DES quasars
Short Name:
J/ApJ/862/123
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present accretion disk size measurements for 15 luminous quasars at 0.7<=z<=1.9 derived from griz light curves from the Dark Energy Survey. We measure the disk sizes with continuum reverberation mapping using two methods, both of which are derived from the expectation that accretion disks have a radial temperature gradient and the continuum emission at a given radius is well described by a single blackbody. In the first method we measure the relative lags between the multiband light curves, which provides the relative time lag between shorter and longer wavelength variations. From this, we are only able to constrain upper limits on disk sizes, as many are consistent with no lag the 2{sigma} level. The second method fits the model parameters for the canonical thin disk directly rather than solving for the individual time lags between the light curves. Our measurements demonstrate good agreement with the sizes predicted by this model for accretion rates between 0.3 and 1 times the Eddington rate. Given our large uncertainties, our measurements are also consistent with disk size measurements from gravitational microlensing studies of strongly lensed quasars, as well as other photometric reverberation mapping results, that find disk sizes that are a factor of a few (~3) larger than predictions.
309. Group of quasars
ID:
ivo://CDS.VizieR/J/MNRAS/249/218
Title:
Group of quasars
Short Name:
J/MNRAS/249/218
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have found evidence for a large, elongated group of at least ten quasars with largest dimension ~100-200h-1Mpc at z~1.3, in the direction of ESO/SERC field 927, which has the field centre (1950) 10h40m00s, 05deg00'00". There are probably further members that have not yet been observed. The morphology of the group seems to be like a clump, but there might be some sub-grouping on scales ~20h-1Mpc. The group is similar in size and number of quasars to that found by Crampton, Cowley & Hartwick (1989). The fact that two such groups are now known is evidence that the distribution of quasars is not so simple as was previously thought: at large scales (>10h-1Mpc) the majority of quasars may be distributed uniformly and at random, but rare, large groups also occur. The groups may be large physical structures, but a strong association with the large structures of galaxies seems doubtful.
310. GRS 1915+105 timing analysis
ID:
ivo://CDS.VizieR/J/A+A/513/A21
Title:
GRS 1915+105 timing analysis
Short Name:
J/A+A/513/A21
Date:
21 Oct 2021
Publisher:
CDS
Description:
GRS 1915+105 was observed by BeppoSAX for about 10 days in October 2000. For about 80% of the time, the source was in the variability class rho, characterised by a series of recurrent bursts. We describe the results of the timing analysis performed on the MECS (1.6-10keV) and PDS (15-100keV) data. The X-ray count rate from GRS 1915+105 showed an increasing trend with different characteristics in the various energy bands: in the bands (1.6-3keV) and (15-100keV), it was nearly stable in the first part of the pointing and increased in a rather short time by about 20%, while in the energy range (3-10keV) the increase had a smoother trend.