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Start Over Subject quasars Validation Level 2
491. MgII and FeII flux of the blazar 3C 454.3
ID:
ivo://CDS.VizieR/J/ApJ/763/L36
Title:
MgII and FeII flux of the blazar 3C 454.3
Short Name:
J/ApJ/763/L36
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the detection of a statistically significant flare-like event in the MgII {lambda}2800 emission line of 3C 454.3 during the outburst of autumn 2010. The highest levels of emission line flux recorded over the monitoring period (2008-2011) coincide with a superluminal jet component traversing through the radio core. This finding crucially links the broad emission line fluctuations to the non-thermal continuum emission produced by relativistically moving material in the jet and hence to the presence of broad-line region clouds surrounding the radio core. If the radio core were located at several parsecs from the central black hole, then our results would suggest the presence of broad-line region material outside the inner parsec where the canonical broad-line region is envisaged to be located. We briefly discuss the implications of broad emission line material ionized by non-thermal continuum in the context of virial black hole mass estimates and gamma-ray production mechanisms.
492. MgII and LRGs cross-correlation analysis
ID:
ivo://CDS.VizieR/J/ApJ/698/819
Title:
MgII and LRGs cross-correlation analysis
Short Name:
J/ApJ/698/819
Date:
21 Oct 2021
Publisher:
CDS
Description:
We analyze the cross-correlation of MgII({lambda}2796, 2803) quasar absorption systems with luminous red galaxies (LRGs) from the Fifth Data Release (DR5) of the Sloan Digital Sky Survey. The absorption line sample consists of 2705 unambiguously intervening MgII absorption systems, detected at a 4{sigma} level, covering a redshift range (0.36<=z_abs_<=0.8) and a rest equivalent-width range of 0.8{AA}<=W^{lambda}2796^_r_<=5.0{AA}. We cross-correlate these absorbers with 1495604 LRGs with accurate photometric redshifts in the same redshift range and examine the relationship of MgII equivalent width and clustering amplitude.
493. MgII-BAL quasar variability in SDSS spectra
ID:
ivo://CDS.VizieR/J/ApJS/242/28
Title:
MgII-BAL quasar variability in SDSS spectra
Short Name:
J/ApJS/242/28
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present absorption variability results for 134 bona fide MgII broad absorption-line (BAL) quasars at 0.46<=z<=2.3 covering days to ~10yr in the rest frame. We use multiple-epoch spectra from the Sloan Digital Sky Survey, which has delivered the largest such BAL variability sample ever studied. MgII-BAL identifications and related measurements are compiled and presented in a catalog. We find a remarkable time-dependent asymmetry in the equivalent width (EW) variation from the sample, such that weakening troughs outnumber strengthening troughs, the first report of such a phenomenon in BAL variability. Our investigations of the sample further reveal that (i) the frequency of BAL variability is significantly lower (typically by a factor of 2) than that in high-ionization BALQSO samples, (ii) MgII-BAL absorbers tend to have relatively high optical depths and small covering factors along our line of sight, (iii) there is no significant EW-variability correlation between MgII troughs at different velocities in the same quasar, and (iv) the EW-variability correlation between MgII and AlIII BALs is significantly stronger than that between MgII and CIV BALs at the same velocities. These observational results can be explained by a combined transverse-motion/ionization-change scenario, where transverse motions likely dominate the strengthening BALs while ionization changes and/or other mechanisms dominate the weakening BALs.
494. MgII/FeII absorbers in 2dF-quasar survey
ID:
ivo://CDS.VizieR/J/A+A/410/33
Title:
MgII/FeII absorbers in 2dF-quasar survey
Short Name:
J/A+A/410/33
Date:
21 Oct 2021
Publisher:
CDS
Description:
We use the first data release of the 2-degree Field quasar survey (Cat. <VII/223>) to investigate the effect of gravitational magnification by foreground absorbing systems on background quasars. We select two populations of quasars from this sample: one with strong MgII/FeII absorbers and one without. The selection is done in such a way that the two populations have the same redshift distribution and the absorber detection procedure discards possible biases with quasar magnitude.
495. MgII line vs 3000{AA} continuum analysis in 68 QSOs
ID:
ivo://CDS.VizieR/J/ApJ/843/30
Title:
MgII line vs 3000{AA} continuum analysis in 68 QSOs
Short Name:
J/ApJ/843/30
Date:
21 Oct 2021
Publisher:
CDS
Description:
We investigate the relationship between the MgII{lambda}2798 emission line and the 3000{AA} continuum variations using a sample of 68 intermediate-redshift (z~0.65-1.50) broad-line quasars spanning a bolometric luminosity range of 44.49erg/s<=logL_bol_<=46.31erg/s (Eddington ratio from ~0.026 to 0.862). This sample is constructed from SDSS-DR7Q and BOSS-DR12Q, each with at least two spectroscopic epochs in SDSS-I/II/III surveys. In addition, we adopt the following signal-to-noise ratio (S/N) selection criteria: (a) for MgII and the 3000{AA} continuum, S/N>=10; and (b) for narrow lines, S/N>=5. All our quasar spectra are recalibrated based on the assumption of constant narrow emission- line fluxes. In an analysis of spectrum-to-spectrum variations, we find a fairly close correlation (Spearman {rho}=0.593) between the variations in broad MgII and in the continuum. This is consistent with the idea that MgII is varying in response to the continuum emission variations. Adopting the modified weighted least squares regression method, we statistically constrain the slopes (i.e., the responsivity {alpha} of the broad MgII) between the variations in both components for the sources in different luminosity bins after eliminating intrinsic biases introduced by the rescaling process itself. It is shown that the responsivity is quite small (average {bar}{alpha}~0.464) and anti- correlates with the quasar luminosity. Our results indicate that high signal- to-noise flux measurements are required to robustly detect the intrinsic variability and the time lag of the MgII line.
496. 144MHz radio fluxes of z>5 quasars
ID:
ivo://CDS.VizieR/J/A+A/656/A137
Title:
144MHz radio fluxes of z>5 quasars
Short Name:
J/A+A/656/A137
Date:
17 Mar 2022 14:39:39
Publisher:
CDS
Description:
Optically luminous quasars at z>5 are important probes of super-massive black hole (SMBH) formation. With new and future radio facilities, the discovery of the brightest low-frequency radio sources in this epoch would be an important new probe of cosmic reionization through 21-cm absorption experiments. We present the result of a study of the low-frequency radio properties of a sample of 115 known spectroscopically confirmed z>5 quasars using the second data release of the Low Frequency Array (LOFAR) Two Meter Sky survey (LoTSS-DR2), reaching noise levels of 80uJy/beam (at 144MHz) over an area of 5720 square degrees. We find that 41 sources (36%) are detected in LoTSS-DR2 at >2{sigma} significance and we explore the evolution of their radio properties (power, spectral index, and radio loudness) as a function of redshift and rest-frame ultra-violet properties.
497. Michigan Emission-Line Objects
ID:
ivo://CDS.VizieR/VII/171
Title:
Michigan Emission-Line Objects
Short Name:
VII/171
Date:
21 Oct 2021
Publisher:
CDS
Description:
The objects of this catalogue were detected by using the 61-cm aperture Curtis Schmidt telescope in combination with a thin objective prism (1.8{deg}) at the Cerro Tololo Inter-American Observatory. The low-dispersion spectra (174nm/mm at H{beta}) cover the wavelength range between 5350 and 3400 {AA}, where the emission lines such that those of [OII], [OIII] and Ly{alpha} are visible. The objects could be detected up to 18th magnitude. Note that the list archived here is not the same as the published lists (see the "References" section below): the positions in the "catalog.dat" file are generally more accurate than those in the original publication and the origin for these is not known. In the printed lists of papers , information presented for each object also includes image dimensions from the Palomar Observatory Sky Survey, an estimated continuum apparent magnitude, a redshift estimate when feasible, or (for galaxies) a spectral classification which involves compactness, color, and line-strength parameters.
498. Microlensing maps for a cusp configuration
ID:
ivo://CDS.VizieR/J/A+A/553/A53
Title:
Microlensing maps for a cusp configuration
Short Name:
J/A+A/553/A53
Date:
21 Oct 2021
Publisher:
CDS
Description:
We provide the microlensing maps generated to study microlensing in the mid-infrared range for a cusp-configuration lensed AGN. The maps provided correspond to images which are respectively saddle-point and minimum of the arrival time surface. We also provide simulated images of sources with a disc-like brightness profile or a ring-like brightness profile corresponding to an accretion disc or a torus brightness distribution. These source profiles should be convolved with microlensing maps of the same spatial resolution to simulate microlensing of the corresponding source and generate probability density function (PDF) of microlensing similar to those shown in Figures 3,4,5,8. These maps can also be used to generate synthetic microlensing lightcurves (Figure 9) or derive PDF for the Rcusp relation (Figure 10).
499. Microquasar candidates
ID:
ivo://CDS.VizieR/J/A+A/477/125
Title:
Microquasar candidates
Short Name:
J/A+A/477/125
Date:
21 Oct 2021
Publisher:
CDS
Description:
Microquasars are ideal natural laboratories for understanding accretion/ejection processes, studying the physics of relativistic jets, and testing gravitational phenomena. Nevertheless, these objects are difficult to find in our Galaxy. The main goal of this work is to increase the number of known systems of this kind, which should allow better testing of high-energy phenomena and more realistic statistical studies of this galactic population to be made. We have developed an improved search strategy based on positional cross-identification with very restrictive selection criteria to find new MQs, taking advantage of more sensitive modern X-ray data. To do this, we made combined use of the radio, infrared, and X-ray properties of the sources, using different available catalogs.
500. Mid-IR QSO spectral templates
ID:
ivo://CDS.VizieR/J/MNRAS/438/2317
Title:
Mid-IR QSO spectral templates
Short Name:
J/MNRAS/438/2317
Date:
21 Oct 2021
Publisher:
CDS
Description:
Mid-infrared (MIR) quasar spectra exhibit a suite of emission features including high ionization coronal lines from the narrow-line region illuminated by the ionizing continuum, broad dust bumps from silicates and graphites, and polycyclic aromatic hydrocarbon (PAH) features from star formation in the host galaxy. However, in Spitzer Infared Spectrograph (IRS) data, few features are detected in most individual spectra because of typically low signal-to-noise ratios (S/N). By generating spectral composites from over 180 IRS observations of Sloan Digital Sky Survey broad-line quasars, we boost the S/N and reveal features in the complex spectra that are otherwise lost in the noise. In addition to an overall composite, we generate composites in three different luminosity bins that span the range of 5.6{mu}m luminosities of 10^40^-10^46^ (erg/s). We detect the high-ionization, forbidden emission lines of [SIV], [OIV] and [NeV] {lambda}14um in all templates and PAH features in all but the most luminous template.

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