- ID:
- ivo://CDS.VizieR/J/ApJS/194/45
- Title:
- QSO properties from SDSS-DR7
- Short Name:
- J/ApJS/194/45
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a compilation of properties of the 105783 quasars in the Sloan Digital Sky Survey Data Release 7 (DR7) quasar catalog (Cat. VII/260). In this product, we compile continuum and emission line measurements around the H{alpha}, H{beta}, MgII, and CIV regions, as well as other quantities such as radio properties, and flags indicating broad absorption line quasars, disk emitters, etc. We also compile virial black hole mass estimates based on various calibrations. For the fiducial virial mass estimates we use the Vestergaard & Peterson (VP06; 2006ApJ...641..689V) calibrations for H{beta} and CIV, and our own calibration for MgII which matches the VP06 H{beta} masses on average. We describe the construction of this catalog and discuss its limitations.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/631/A78
- Title:
- QSOs at z~6 spectral cubes
- Short Name:
- J/A+A/631/A78
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Outflows in quasars during the early epochs of galaxy evolution are an important part of the feedback mechanisms potentially affecting the evolution of the host galaxy. However, systematic observations of outflows are only now becoming possible with the advent of sensitive mm telescopes. In this study we use spectral stacking methods to search for faint high velocity outflow signal in a sample of [CII] detected, z~6 quasars. We search for broad emission line signatures from high-velocity outflows for a sample of 26 z~6 quasars observed with ALMA, with a detection of the [CII] line. The observed emission lines of the sources are dominated by the host galaxy, and outflow emission is not detected for the individual sources. We use a spectral line stacking analysis developed for interferometric data to search for outflow emission. We stack both extracted spectra and the full spectral cubes. We also investigate the possibility that only a sub-set of our sample contributes to the stacked outflow emission. We find only a tentative detection of a broad emission line component in the stacked spectra. When taking a region of about 2 arcsec around the source central position of the stacked cubes, the stacked line shows an excess emission due to a broad component of 1.1-1.5 sigma, but the significance drops to 0.4-0.7 sigma when stacking the extracted spectra from a smaller region. The broad component can be characterised by a line width of full width half max FWHM > 700 km/s. Furthermore, we find a sub-sample of 12 sources the stack of which maximises the broad component emission. The stack of this sub-sample shows an excess emission due to a broad component of 1.2-2.5 sigma. The stacked line of these sources has a broad component of FWHM>775km/s. Deeper ALMA observations are necessary to confirm the presence of a broad component in the individual spectra.
- ID:
- ivo://CDS.VizieR/J/MNRAS/400/1493
- Title:
- QSOs Lyman alpha emission line spectra
- Short Name:
- J/MNRAS/400/1493
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Arguably the best hope of understanding the tail end of the re-ionization of the intergalactic medium (IGM) at redshift z>6 is through the detection and characterization of the Gunn-Peterson damping wing absorption of the IGM in bright quasar spectra. However, the use of quasar spectra to measure the IGM damping wing requires a model of the quasar's intrinsic Lyman{alpha} emission line. Here we quantify the uncertainties in the intrinsic line shapes, and how those uncertainties affect the determination of the IGM neutral fraction. We have assembled a catalogue of high-resolution Hubble Space Telescope spectra of the emission lines of unobscured low-redshift quasars, and have characterized the variance in the shapes of their lines. We then add simulated absorption from the high-redshift IGM to these quasar spectra in order to determine the corresponding uncertainties in re-ionization constraints using current and future samples of z>6 quasar spectra. We find that, if the redshift of the Lyman{alpha} emission line is presumed to coincide with the systemic redshift determined from metal lines, the inferred IGM neutral fraction is systematically biased to low values due to a systematic blueshift of the Lyman{alpha} line relative to the metal lines.
- ID:
- ivo://CDS.VizieR/J/AJ/112/62
- Title:
- Quasar absorption-line systems
- Short Name:
- J/AJ/112/62
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A survey of quasar absorbers was conducted using the Infrared Astronomical Satellite (IRAS) database. Quasars with known intervening absorption-line systems and broad absorption line (BAL) QSOs were selected primarily from Junkkarinen et al. (1991ApJS...77..203J). Of the 570 quasars with IRAS data, 52 showed 3{sigma} or better detections in at least one band in SCANPI analysis. The origin of the IRAS flux could be from the absorption-line systems, other galaxies, or the quasar itself. The spectral energy distributions for quasars detected in the absorption-line sample and BAL QSOs were found to be redder than those of two control samples which suggests that some of the IRAS flux may arise in dust associated with the intervening galaxies. IRAS SUPERSCANPI processing was carried out for 77 quasars with known MgII absorption at Zabs<1 to investigate the ensemble far-infrared properties of these objects. SUPERSCANPI processing evaluates the median flux for many different positions on the sky, resulting in an improvement in the effective sensitivity. A control sample consisting of objects with no MgII absorption known at Zabs<1 but with the same distribution of absolute V-magnitude, Zem and radio-loud fraction for the background quasars was also processed. The MgII sample was detected at 3{sigma} or better in all four IRAS bands with a significantly larger flux than the control sample at 60{mu}m and 100{mu}m. If this far-infrared emission is from the absorber galaxies, then the far-infrared luminosity of the composite MgII absorber was found to be comparable to that of a starbursting galaxy, although such a high star-formation rate is inconsistent with the optical and near-infrared colors of low-redshift MgII systems. Four of the quasars with individual IRAS detections have intervening galaxies identified with the MgII absorption-lines. The spectral energy distributions of these galaxies imply far-infrared luminosities in excess of what Arp 220 would give at their redshifts. While all the external evidence suggests that the detection of far-infrared emission from the absorber sample may not be connected to the presence of the MgII absorber, we discuss future observations which may help explain our results.
2055. Quasar black hole masses
- ID:
- ivo://CDS.VizieR/J/ApJ/669/791
- Title:
- Quasar black hole masses
- Short Name:
- J/ApJ/669/791
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the time-dependent variations of ultraviolet (UV) black hole mass estimates of quasars in the Sloan Digital Sky Survey (SDSS). From SDSS spectra of 615 high-redshift (1.69<z<4.75) quasars with spectra from two epochs, we estimate black hole masses using a single-epoch technique, which employs an additional, automated night-sky line removal and relies on UV continuum luminosity and CIV {lambda}1549 emission-line dispersion. Mass estimates show variations between epochs at about the 30% level for the sample as a whole. We determine that for our full sample, measurement error in the line dispersion likely plays a larger role than the inherent variability in terms of contributing to variations in mass estimates between epochs. However, we use the variations in quasars with r-band spectral signal-to-noise ratio greater than 15 to estimate that the contribution to these variations from inherent variability is roughly 20%. We conclude that these differences in black hole mass estimates between epochs indicate that variability does not make a large contribution to the current factor of 2 scatter between mass estimates derived from low- and high-ionization emission lines.
- ID:
- ivo://CDS.VizieR/J/A+A/585/A87
- Title:
- Quasar composite made from bright QSOs
- Short Name:
- J/A+A/585/A87
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Quasi-stellar object (QSO) spectral templates are important both to QSO physics and for investigations that use QSOs as probes of intervening gas and dust. However, combinations of various QSO samples obtained at different times and with different instruments so as to expand a composite and to cover a wider rest frame wavelength region may create systematic effects, and the contribution from QSO hosts may contaminate the composite. We have constructed a composite spectrum from luminous blue QSOs at 1<z<2.1 selected from the Sloan Digital Sky Survey (SDSS). The observations with X-shooter simultaneously cover ultraviolet (UV) to near-infrared (NIR) light, which ensures that the composite spectrum covers the full rest-frame range from Ly{beta} to 11350{AA} without any significant host contamination. Assuming a power-law continuum for the composite we find a spectral slope of {alpha}{lambda}=1.70+/-0.01, which is steeper than previously found in the literature. We attribute the differences to our broader spectral wavelength coverage, which allows us to effectively avoid fitting any regions that are affected either by strong QSO emissions lines (e.g., Balmer lines and complex [FeII] blends) or by intrinsic host galaxy emission. Finally, we demonstrate the application of the QSO composite spectrum for evaluating the reddening in other QSOs.
- ID:
- ivo://CDS.VizieR/J/MNRAS/266/317
- Title:
- Quasars in ESO/SERC field 927
- Short Name:
- J/MNRAS/266/317
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the spectroscopic observations of 56 quasars that were discovered by AQD (Automated Quasar Detection) in a field of ~25.3deg2, centred at (1950) RA l0h40m00s, Dec. 05deg00'00". These observations, with the CTIO 4-m telescope, led to the discovery by Clowes & Campusano of a large group of quasars with size ~100-200h^-1^Mpc at z~1.3. Quasars of particular interest are noted, including one that is a BAL quasar with z~1.78.
- ID:
- ivo://CDS.VizieR/J/ApJ/679/962
- Title:
- Quasars with strong nitrogen emission lines
- Short Name:
- J/ApJ/679/962
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on 293 quasars with strong NIV] {lambda}1486 or NIII] {lambda}1750 emission lines (rest-frame equivalent width >3{AA}) at 1.7<z<4.0 selected from the Sloan Digital Sky Survey (SDSS) Fifth Data Release (Cat. VII/252). These nitrogen-rich (N-rich) objects comprise ~1.1% of the SDSS quasars. The comparison between the N-rich quasars and other quasars shows that the two quasar subsets share many common properties. We also confirm previous results that N-rich quasars have much stronger Ly{alpha} and NV {lambda}1240 emission lines. Strong nitrogen emission in all ionization states indicates high overall nitrogen abundances in these objects. We find evidence that the nitrogen abundance is closely related to quasar radio properties.
- ID:
- ivo://CDS.VizieR/J/AJ/132/2665
- Title:
- QUEST2 BRI photometry of Taurus-Auriga PMS
- Short Name:
- J/AJ/132/2665
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a drift-scan survey covering a ~5{deg}x5{deg} region toward the southern portion of the Taurus-Auriga molecular cloud. Data taken in the B,R,I filters with the Quest-2 camera on the Palomar 48 inch (1.2m) Samuel Oschin Telescope were combined with Two Micron All Sky Survey near-infrared photometry to select candidate young stars. Follow-up optical spectroscopy of 190 candidates led to the identification of 42 new low-mass pre-main-sequence stars with spectral types M4-M8, of which approximately half exhibit surface gravity signatures similar to known Taurus stars, while the other half exhibit surface gravity signatures similar to members of the somewhat older Upper Scorpius, TW Hya, and Pic associations.
- ID:
- ivo://CDS.VizieR/J/A+A/644/A109
- Title:
- Quiet-sun hydrogen Lyman-alpha line profile
- Short Name:
- J/A+A/644/A109
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The solar radiation in the Lyman-alpha spectral line of hydrogen plays a significant role in the illumination of chromospheric and coronal structures, such as prominences, spicules, chromospheric fibrils, cores of coronal mass ejections, and solar wind. Moreover, it is important for the investigation of the heliosphere, Earth's ionosphere, and the atmospheres of planets, moons, and comets. We derive a reference quiet-Sun Lyman-alpha spectral profile that is representative of the Lyman-alpha radiation from the solar disk during a minimum of solar activity. This profile can serve as an incident radiation boundary condition for the radiative transfer modelling of chromospheric and coronal structures. Because the solar radiation in the Lyman lines is not constant over time but varies significantly with the solar cycle, we provide a method for the adaptation of the incident radiation Lyman line profiles (Lyman-alpha and higher lines) to a specific date. Moreover, we analyse how the change in the incident radiation influences the synthetic spectra produced by the radiative transfer modelling. We used SOHO/SUMER Lyman-alpha raster scans obtained without the use of the attenuator in various quiet-Sun regions on the solar disk. The observations were performed on three consecutive days (June 24, 25, and 26, 2008) during a period of minimum solar activity. The reference Lyman-alpha profile was obtained as a spatial average over eight available raster scans. To take into account the Lyman-alpha variation with the solar cycle, we used the LISIRD composite Lyman-alpha index. To estimate the influence of the change in the incident radiation in the Lyman lines on the results of radiative transfer models, we used a 2D prominence fine structure model. We present the reference quiet-Sun Lyman-alpha profile and a table of coefficients describing the variation of the Lyman lines with the solar cycle throughout the lifetime of SOHO. The analysis of the influence of the change in the incident radiation shows that the synthetic spectra are strongly affected by the modification of the incident radiation boundary condition. The most pronounced impact is on the central and integrated intensities of the Lyman lines. There, the change in the synthetic spectra can often have the same amplitude as the change in the incident radiation itself. The impact on the specific intensities in the peaks of reversed Lyman-line profiles is smaller but still significant. The hydrogen Halpha line can also be considerably affected, despite the fact that the Halpha radiation from the solar disk does not vary with the solar cycle.
