Search

Start Over Subject quasars Content Level Research
821. SDSS quasar catalog, sixteenth data release (DR16Q)
ID:
ivo://CDS.VizieR/VII/289
Title:
SDSS quasar catalog, sixteenth data release (DR16Q)
Short Name:
VII/289
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the final Sloan Digital Sky Survey IV (SDSS-IV) quasar catalog from Data Release 16 of the extended Baryon Oscillation Spectroscopic Survey (eBOSS). This catalog comprises the largest selection of spectroscopically confirmed quasars to date. The full catalog includes two subcatalogs (the current versions are DR16Q_v4 and DR16Q_Superset_v3 at http://data.sdss.org/sas/dr16/eboss/qso/DR16Q): a "superset" of all SDSS-IV/eBOSS objects targeted as quasars containing 1,440,615 observations and a quasar-only catalog containing 750,414 quasars, including 225,082 new quasars appearing in an SDSS data release for the first time, as well as known quasars from SDSS-I/II/III. We present automated identification and redshift information for these quasars alongside data from visual inspections for 320,161 spectra. The quasar-only catalog is estimated to be 99.8% complete with 0.3%-1.3% contamination. Automated and visual inspection redshifts are supplemented by redshifts derived via principal component analysis and emission lines. We include emission-line redshifts for H{alpha}, H{beta}, MgII, CIII], CIV, and Ly{alpha}. Identification and key characteristics generated by automated algorithms are presented for 99,856 broad absorption-line quasars and 35,686 damped Lyman alpha quasars. In addition to SDSS photometric data, we also present multiwavelength data for quasars from the Galaxy Evolution Explorer, UKIDSS, the Wide-field Infrared Survey Explorer, FIRST, ROSAT/2RXS, XMM-Newton, and Gaia.
822. SDSS quasar catalog: tenth data release
ID:
ivo://CDS.VizieR/VII/270
Title:
SDSS quasar catalog: tenth data release
Short Name:
VII/270
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the Data Release 10 Quasar (DR10Q) catalog from the Baryon Oscillation Spectroscopic Survey (BOSS) of the Sloan Digital Sky Survey III. The catalog includes all BOSS objects that were targeted as quasar candidates during the first 2.5 years of the survey and that are confirmed as quasars via visual inspection of the spectra, have luminosities Mi[z=2]<-20.5 (in a LCDM cosmology with H_0_=70km/s/Mpc, Om=0.3, and Ol=0.7), and either display at least one emission line with a full width at half maximum (FWHM) larger than 500km/s or, if not, have interesting/complex absorption features. The catalog also includes known quasars (mostly from SDSS-I and II) that were reobserved by BOSS. The catalog contains 166,583 quasars (74,454 are new discoveries since SDSS-DR9) detected over 6,373deg^2^ with robust identification and redshift measured by a combination of principal component eigenspectra. The number of quasars with z>2.15 (117,668) is ~5 times greater than the number of z>2.15 quasars known prior to BOSS. Redshifts and FWHMs are provided for the strongest emission lines (CIV, CIII, MgII). The catalog identifies 16,461 broad absorption line quasars and gives their characteristics. For each object, the catalog presents five-band (u, g, r, i, z) CCD-based photometry with typical accuracy of 0.03mag and information on the optical morphology and selection method. The catalog also contains X-ray, ultraviolet, near- infrared, and radio emission properties of the quasars, when available, from other large-area surveys. The calibrated digital spectra cover the wavelength region 3,600-10,500{AA} at a spectral resolution in the range 1,300<R<2,500; the spectra can be retrieved from the SDSS Catalog Archive Server. We also provide a supplemental list of an additional 2,376 quasars that have been identified among the galaxy targets of the SDSS-III/BOSS.
823. SDSS quasar catalog: twelfth data release
ID:
ivo://CDS.VizieR/VII/279
Title:
SDSS quasar catalog: twelfth data release
Short Name:
VII/279
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the Data Release 12 Quasar catalog (DR12Q) from the Baryon Oscillation Spectroscopic Survey (BOSS) of the Sloan Digital Sky SurveyIII. This catalog includes all SDSS-III/BOSS objects that were spectroscopically targeted as quasar candidates during the full survey and that are confirmed as quasars via visual inspection of the spectra, have luminosities M_i_[z=2]< -20.5 (in a {Lambda}CDM cosmology with H_0_=70km/s/Mpc, {Omega}_M_=0.3, and {Omega}_{Lambda}_=0.7), and either display at least one emission line with a full width at half maximum (FWHM) larger than 500km/s or, if not, have interesting/complex absorption features. The catalog also includes previously known quasars (mostly from SDSS-I andII) that were reobserved by BOSS. The catalog contains 297 301 quasars (272 026 are new discoveries since the beginning of SDSS-III) detected over 9376deg^2^ with robust identification and redshift measured by a combination of principal component eigenspectra. The number of quasars with z>2.15 (184 101, of which 167 742 are new discoveries) is about an order of magnitude greater than the number of z>2.15 quasars known prior to BOSS. Redshifts and FWHMs are provided for the strongest emission lines (CIV, CIII], MgII). The catalog identifies 29 580 broad absorption line quasars and lists their characteristics. For each object, the catalog presents five-band (u, g, r, i, z) CCD-based photometry with typical accuracy of 0.03mag together with some information on the optical morphology and the selection criteria. When available, the catalog also provides information on the optical variability of quasars using SDSS and Palomar Transient Factory multi-epoch photometry. The catalog also contains X-ray, ultraviolet, near-infrared, and radio emission properties of the quasars, when available, from other large-area surveys. The calibrated digital spectra, covering the wavelength region 3600-10 500{AA} at a spectral resolution in the range 1300<R<2500, can be retrieved from the SDSS Catalog Archive Server. We also provide a supplemental list of an additional 4841 quasars that have been identified serendipitously outside of the superset defined to derive the main quasar catalog.
824. SDSS quasar catalog with Swift observations
ID:
ivo://CDS.VizieR/J/ApJS/201/10
Title:
SDSS quasar catalog with Swift observations
Short Name:
J/ApJS/201/10
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have compiled a catalog of optically selected quasars with simultaneous observations in UV/optical and X-ray bands by the Swift Gamma-ray Burst Explorer. Objects in this catalog are identified by matching the Swift pointings with the Sloan Digital Sky Survey Data Release 5 quasar catalog. The final catalog contains 843 objects, among which 637 have both Ultraviolet Optical Telescope (UVOT) and X-Ray Telescope (XRT) observations and 354 of which are detected by both instruments. The overall X-ray detection rate is ~60% which rises to ~85% among sources with at least 10ks of XRT exposure time. We construct the time-averaged spectral energy distribution (SED) for each of the 354 quasars using UVOT photometric measurements and XRT spectra. From model fits to these SEDs, we find that the big blue bump contributes about ~0.3 dex to the quasar luminosity. We re-visit the {alpha}_ox_-L_2500_{AA} relation by selecting a clean sample with only Type 1 radio-quiet quasars; the dispersion of this relation is reduced by at least 15% compared with studies that use non-simultaneous UV/optical and X-ray data.
825. SDSS quasar lens search
ID:
ivo://CDS.VizieR/J/AJ/132/999
Title:
SDSS quasar lens search
Short Name:
J/AJ/132/999
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present an algorithm for selecting a uniform sample of gravitationally lensed quasar candidates from low-redshift (0.6<z<2.2) quasars brighter than i=19.1 that have been spectroscopically identified in the Sloan Digital Sky Survey (SDSS). Our algorithm uses morphological and color selections that are intended to identify small- and large-separation lenses, respectively. Our selection algorithm only relies on parameters that the SDSS standard image processing pipeline generates, allowing easy and fast selection of lens candidates. The algorithm has been tested against simulated SDSS images, which adopt distributions of field and quasar parameters taken from the real SDSS data as input. Furthermore, we take differential reddening into account. We find that our selection algorithm is almost complete down to separations of 1" and flux ratios of 10^-0.5^.
826. SDSS quasar lens search. II.
ID:
ivo://CDS.VizieR/J/AJ/135/496
Title:
SDSS quasar lens search. II.
Short Name:
J/AJ/135/496
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the first results of our systematic search for strongly lensed quasars using the spectroscopically confirmed quasars in the Sloan Digital Sky Survey (SDSS). Among 46420 quasars from the SDSS Data Release 3 (~4188deg^2^), we select a subsample of 22683 quasars that are located at redshifts between 0.6 and 2.2 and are brighter than the Galactic extinction-corrected i-band magnitude of 19.1. We identify 220 lens candidates from the quasar subsample, for which we conduct extensive and systematic follow-up observations in optical and near-infrared wavebands, in order to construct a complete lensed quasar sample at image separations between 1" and 20" and flux ratios of faint to bright lensed images larger than 10^-0.5^. We construct a statistical sample of 11 lensed quasars. Ten of these are galaxy-scale lenses with small image separations (~1"-2") and one is a large separation (15") system which is produced by a massive cluster of galaxies, representing the first statistical sample of lensed quasars including both galaxy- and cluster-scale lenses. The Data Release 3 spectroscopic quasars contain an additional 11 lensed quasars outside the statistical sample.
827. SDSS Quasar Lens Search. IV.
ID:
ivo://CDS.VizieR/J/AJ/140/403
Title:
SDSS Quasar Lens Search. IV.
Short Name:
J/AJ/140/403
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the second report of our systematic search for strongly lensed quasars from the data of the Sloan Digital Sky Survey (SDSS). From extensive follow-up observations of 136 candidate objects, we find 36 lenses in the full sample of 77,429 spectroscopically confirmed quasars in the SDSS Data Release 5.
828. SDSS Quasar Lens Search. V. Final catalog
ID:
ivo://CDS.VizieR/J/AJ/143/119
Title:
SDSS Quasar Lens Search. V. Final catalog
Short Name:
J/AJ/143/119
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the final statistical sample of lensed quasars from the Sloan Digital Sky Survey (SDSS) Quasar Lens Search (SQLS). The well-defined statistical lens sample consists of 26 lensed quasars brighter than i=19.1 and in the redshift range of 0.6<z<2.2 selected from 50826 spectroscopically confirmed quasars in the SDSS Data Release 7 (DR7), where we restrict the image separation range to 1"<{theta}<20" and the i-band magnitude differences in two images to be smaller than 1.25mag. The SDSS-DR7 quasar catalog also contains 36 additional lenses identified with various techniques. In addition to these lensed quasars, we have identified 81 pairs of quasars from follow-up spectroscopy, 26 of which are physically associated binary quasars. The statistical lens sample covers a wide range of image separations, redshifts, and magnitudes, and therefore is suitable for systematic studies of cosmological parameters and surveys of the structure and evolution of galaxies and quasars.
829. SDSS quasars balmer emission lines
ID:
ivo://CDS.VizieR/J/ApJ/789/140
Title:
SDSS quasars balmer emission lines
Short Name:
J/ApJ/789/140
Date:
21 Oct 2021
Publisher:
CDS
Description:
A small fraction of quasars have long been known to show bulk velocity offsets (of a few hundred to thousands of km/s) in the broad Balmer lines with respect to the systemic redshift of the host galaxy. Models to explain these offsets usually invoke broad-line region gas kinematics/asymmetry around single black holes (BHs), orbital motion of massive (~sub-parsec (sub-pc)) binary black holes (BBHs), or recoil BHs, but single-epoch spectra are unable to distinguish between these scenarios. The line-of-sight (LOS) radial velocity (RV) shifts from long-term spectroscopic monitoring can be used to test the BBH hypothesis. We have selected a sample of 399 quasars with kinematically offset broad H{beta} lines from the Sloan Digital Sky Survey (SDSS) Seventh Data Release quasar catalog, and have conducted second-epoch optical spectroscopy for 50 of them. Combined with the existing SDSS spectra, the new observations enable us to constrain the LOS RV shifts of broad H{beta} lines with a rest-frame baseline of a few years to nearly a decade. While previous work focused on objects with extreme velocity offset (>10^3^ km/s), we explore the parameter space with smaller (a few hundred km/s) yet significant offsets (99.7% confidence). Using cross-correlation analysis, we detect significant (99% confidence) radial accelerations in the broad H{beta} lines in 24 of the 50 objects, of ~10-200 km/s/yr with a median measurement uncertainty of ~10 km/s/yr, implying a high fraction of variability of the broad-line velocity on multi-year timescales. We suggest that 9 of the 24 detections are sub-pc BBH candidates, which show consistent velocity shifts independently measured from a second broad line (either H{alpha} or Mg II) without significant changes in the broad-line profiles. Combining the results on the general quasar population studied in Paper I (Shen et al. 2013ApJ...775...49S), we find a tentative anti-correlation between the velocity offset in the first-epoch spectrum and the average acceleration between two epochs, which could be explained by orbital phase modulation when the time separation between two epochs is a non-negligible fraction of the orbital period of the motion causing the line displacement. We discuss the implications of our results for the identification of sub-pc BBH candidates in offset-line quasars and for the constraints on their frequency and orbital parameters.
830. SDSS quasars in SWIRE ELAIS N1 field
ID:
ivo://CDS.VizieR/J/AJ/129/1198
Title:
SDSS quasars in SWIRE ELAIS N1 field
Short Name:
J/AJ/129/1198
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a mid-infrared (MIR) analysis of 35 quasars with spectroscopic redshifts selected from the Spitzer Wide-Area Infrared Extragalactic Survey (SWIRE). We discuss their optical and MIR colors and show that these quasars occupy well-defined regions in MIR color-color space. We examine the issue of type 1 active galactic nuclei candidate selection in detail and propose new selection methods based on MIR colors. The available multiband data allow us to construct two new, well-sampled quasar templates, covering wavelengths from the ultraviolet to the MIR.