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801. SDSS-DR7 QSOs with X-ray and UV luminosities
ID:
ivo://CDS.VizieR/J/ApJ/819/154
Title:
SDSS-DR7 QSOs with X-ray and UV luminosities
Short Name:
J/ApJ/819/154
Date:
21 Oct 2021
Publisher:
CDS
Description:
The observed relation between the soft X-ray and the optical-ultraviolet emission in active galactic nuclei (AGNs) is nonlinear and it is usually parametrized as a dependence between the logarithm of the monochromatic luminosity at 2500{AA} and at 2keV. Previous investigations have found that the dispersion of this relation is rather high (~0.35-0.4 in log units), which may be caused by measurement uncertainties, variability, and intrinsic dispersion due to differences in the AGN physical properties (e.g., different accretion modes). We show that, once optically selected quasars with homogeneous SED and X-ray detection are selected, and dust reddened and/or gas obscured objects are not included, the measured dispersion drops to significantly lower values (i.e., ~0.21-0.24dex). We show that the residual dispersion is due to some extent to variability, and to remaining measurement uncertainties. Therefore, the real physical intrinsic dispersion should be <0.21dex. Such a tight relation, valid over four decades in luminosity, must be the manifestation of an intrinsic (and universal) physical relation between the disk, emitting the primary radiation, and the hot electron corona emitting X-rays.
802. SDSS-DR5 quasar catalog
ID:
ivo://CDS.VizieR/VII/252
Title:
SDSS-DR5 quasar catalog
Short Name:
VII/252
Date:
21 Oct 2021
Publisher:
CDS
Description:
The fourth edition of the Sloan Digital Sky Survey (SDSS) Quasar Catalog, made from the SDSS Fifth Data Release, contains 77,429 objects; this is an increase of over 30,000 entries since the previous edition (Schneider et al., Cat. <VII/243>). The catalog consists of the objects in the SDSS Fifth Data Release that have luminosities larger than M_i_=-22.0 (in a cosmology with Ho=70km.s-1.Mpc-1, {Omega}_M_=0.3, and {Omega}_{Lambda}_=0.7), have at least one emission line with FWHM larger than 1000km.s-1 or have interesting or complex absorption features, are fainter than i~15.0, and have highly reliable redshifts. The area covered by the catalog is about 5740deg^2^. The quasar redshifts range from 0.08 to 5.41, with a median value of 1.48; the catalog includes 891 quasars at redshifts greater than 4, of which 36 are at redshifts greater than 5. Approximately half of the catalog quasars have i<19; nearly all have i<21. For each object the catalog presents positions accurate to better than 0.2" rms per coordinate, five-band (ugriz) CCD-based photometry with typical accuracy of 0.03mag, and information on the morphology and selection method. The catalog also contains basic radio, near-infrared, and X-ray emission properties of the quasars, when available, from other large-area surveys. The calibrated digital spectra cover the wavelength region 3800-9200{AA} at a spectral resolution of about 2000; the spectra can be retrieved from the public database using the information provided in the catalog. The average SDSS colors of quasars as a function of redshift, derived from the catalog entries, are presented in tabular form. Approximately 96% of the objects in the catalog were discovered by the SDSS.
803. SDSS DR10 radio-loud quasars sample
ID:
ivo://CDS.VizieR/J/A+A/631/A46
Title:
SDSS DR10 radio-loud quasars sample
Short Name:
J/A+A/631/A46
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a study of a sample of 223 radio loud quasars (up to redshift <0.3) in order to investigate their spectral properties. Twenty-six of these radio loud quasars are identified as Flat Spect rum Radio Quasars (FSRQs) and fifty-four are identified as Steep Spectrum Radio Quasars (SSRQs) based on their radio spectral index. We study the [OIII] line properties of these quasars to investigate the origin and properties of blue wings (shift of the profile towards lower wavelengths) and blue outliers (shift of the whole spectroscopic feature). Most of the quasars show blue wings with velocities up to 420km/s. We find that around 17% of the quasars show outliers with velocities spanning 4 19 to -315km/s. Finally, we revisit the M_BH_-{sigma} relation of our sample using [SII]{lambda}6716, 6731 and [OIII] linewidths as surrogates for stellar velocity dispersions, {sigma}, to investigate their location on the M_BH_-{sigma} relation for quiescent galaxies. Due to strong blending of [SII] with H_{alpha}_, we could estimate {sigma}_[SII]_ of only 123 quasars. We find that the radio-loud quasars do not show a relationship between M_BH_ and {sigma}_[SII]/[OIII]_ up to a redshift of 0.3, although they cluster around the local relation. We find an overall offset of 0.12+/-0.05dex of our sample of radio loud quasars from the M_BH_-{sigma} relation of quiescent galaxies. Quasars in our highest redshift bin (z=0.25-0.3) show a deviation of ~0.33+/-0.06dex with respect to the local relation. Implications of the results are discussed.
804. SDSS-DR3 strong MgII absorbers
ID:
ivo://CDS.VizieR/J/ApJ/639/766
Title:
SDSS-DR3 strong MgII absorbers
Short Name:
J/ApJ/639/766
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of two complementary investigations into the nature of strong (rest equivalent width, Wr>1.0{AA}) MgII absorption systems at high redshift. The first line of questioning examines the complete Sloan Digital Sky Survey Data Release 3 set of quasar spectra to determine the evolution of the incidence of strong MgII absorption. This search resulted in 7421 confirmed MgII systems of Wr>1.0{AA}, yielding a >95% complete statistical sample of 4835 absorbers (systems detected in S/N>7 spectral regions) spanning a redshift range 0.35<z<2.3.
805. SDSS DR5 virial black hole masses
ID:
ivo://CDS.VizieR/J/ApJ/680/169
Title:
SDSS DR5 virial black hole masses
Short Name:
J/ApJ/680/169
Date:
21 Oct 2021
Publisher:
CDS
Description:
We compile black hole (BH) masses for ~60000 quasars in the redshift range 0.1~<z~<4.5 included in the Fifth Data Release of the Sloan Digital Sky Survey (Schneider et al. 2007, Cat. VII/252), using virial BH mass estimators based on the H{beta}, MgII, and CIV emission lines.
806. 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.
807. SDSS-GALEX QSO catalog
ID:
ivo://CDS.VizieR/J/AJ/140/1987
Title:
SDSS-GALEX QSO catalog
Short Name:
J/AJ/140/1987
Date:
21 Oct 2021
Publisher:
CDS
Description:
We discuss a sample of ~60000 objects from the combined Sloan Digital Sky Survey-Galaxy Evolution Explorer (SDSS-GALEX) database with UV-optical colors that should isolate QSOs in the redshift range 0.5-1.5. We use SDSS spectra of a subsample of ~4500 to remove stellar and galaxy contaminants in the sample to a very high level, based on the 7-band photometry. We discuss the distributions of redshift, luminosity, and reddening of the 19100 QSOs (~96%) that we estimate to be present in the final sample of 19812 point sources.
808. SDSS-III DR9 DLA catalogue
ID:
ivo://CDS.VizieR/J/A+A/547/L1
Title:
SDSS-III DR9 DLA catalogue
Short Name:
J/A+A/547/L1
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a study of the column density distribution and cosmological mass density of neutral gas from a survey of Damped Lyman-alpha systems in the Sloan Digital Sky Survey III Data Release 9.
809. SDSS J155810.16-003120.0 abundances
ID:
ivo://CDS.VizieR/J/ApJ/649/L61
Title:
SDSS J155810.16-003120.0 abundances
Short Name:
J/ApJ/649/L61
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a measurement of the D/H abundance ratio in a metal-poor damped Ly{alpha}(DLA) system along the sight line of QSO SDSS 1558-0031.
810. SDSS J102839.11+450009.4 Fe II emission lines
ID:
ivo://CDS.VizieR/J/ApJ/674/668
Title:
SDSS J102839.11+450009.4 Fe II emission lines
Short Name:
J/ApJ/674/668
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report identification of SDSS J102839.11+450009.4 as a peculiarly interesting quasar. It shows very prominent narrow emission lines (NELs) in FeII that are remarkably different from the broad FeII multiplets commonly observed in quasars and Seyfert 1 galaxies. The FeII NEL spectrum is dominated in the UV by transitions to the low-lying ground levels with even parity, and by forbidden transitions in the optical, suggesting its formation in a warm collisionally ionized low density medium.