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Start Over Subject quasars Content Level Research
641. QSO J1538+0855 MUSE datacube
ID:
ivo://CDS.VizieR/J/A+A/635/A157
Title:
QSO J1538+0855 MUSE datacube
Short Name:
J/A+A/635/A157
Date:
21 Oct 2021
Publisher:
CDS
Description:
In recent years, Ly{alpha} nebulae have been routinely detected around high redshift, radio-quiet quasars thanks to the advent of the highly sensitive integral field spectrographs. Constraining the physical properties of the Ly{alpha} nebulae is crucial for a full understanding of the circum-galactic medium (CGM). The CGM acts both as a repository for intergalactic and galactic baryons as well as a venue of feeding and feedback processes. The most luminous quasars are privileged test-beds to study these processes, given their large ionising fluxes and dense CGM environments in which they are expected to be embedded.We aim to characterise the rest-frame ultraviolet (UV) emission lines in the CGM around a hyper-luminous, broad emission line, radio-quiet quasar at z~3.6, which exhibits powerful outflows at both nuclear and host galaxy scales.We analyse VLT/MUSE observations of the quasar J1538+08 (Lbol=6*10^47^erg/s), and we performed a search for extended UV emission lines to characterise its morphology, emissivity, kinematics, and metal content.We report the discovery of a very luminous (2*10^44^erg/s), giant (150kpc) Ly{alpha} nebula and a likely associated extended (75kpc) CIV nebula. The Ly{alpha} nebula emission exhibits moderate blueshift (440km/s) compared to the quasar systemic redshift and a large average velocity dispersion (700km/s) across the nebula, while the CIV nebula shows average velocity dispersion of 350km/s. The Ly{alpha} line profile exhibits a significant asymmetry towards negative velocity values at 20-30kpc south of the quasar and is well parametrised by the following two Gaussian components: a narrow (470km/s) systemic one plus a broad (1200km/s), blueshifted (1500km/s) one. Our analysis of the MUSE observation of J1538+08 reveals metal-enriched CGM around this hyper-luminous quasar. Furthermore, our detection of blueshifted emission in the emission profile of the Ly{alpha} nebula suggests that powerful nuclear outflows can propagate through the CGM over tens of kiloparsecs.
642. QSO J1721+8842 spectra
ID:
ivo://CDS.VizieR/J/A+A/657/A113
Title:
QSO J1721+8842 spectra
Short Name:
J/A+A/657/A113
Date:
22 Feb 2022
Publisher:
CDS
Description:
High-redshift binary quasars provide key insights into mergers and quasar activity, and are useful tools for probing the spatial kinematics and chemistry of galaxies along the line-of-sight. However, only three sub-10-kpc binaries have been confirmed above z=1. Gravitational lensing would provide a way to easily resolve such binaries, study them in higher resolution, and provide more sightlines, though the required alignment with a massive foreground galaxy is rare. Through image deconvolution of StanCam Nordic Optical Telescope (NOT) monitoring data, we reveal two further point sources in the known, z~2.38, quadruply lensed quasar (quad), J1721+8842. An ALFOSC/NOT long-slit spectrum shows that the brighter of these two sources is a quasar with z=2.369+/-0.007 based on the CIII] line, while the CIII] redshift of the quad is z=2.364+/-0.003. Lens modelling using point source positions rules out a single source model, favouring an isothermal lens mass profile with two quasar sources separated by ~6.0kpc (0.73") in projection. Given the resolving ability from lensing and current lensed quasar statistics, this discovery suggests a large population of undiscovered, unlensed sub-10-kpc binaries. We also analyse spectra of two images of the quad, showing narrow Ly{alpha} emission within the trough of a proximate damped Lyman-{alpha} absorber (PDLA). An apparent mismatch between the continuum and narrow line flux ratios provides a new potential tool for simultaneously studying microlensing and the quasar host galaxy. Signs of the PDLA are also seen in the second source, however a deeper spectrum is still required to confirm this. Thanks to the multiple lines-of-sight from lensing and two quasar sources, this system offers simultaneous sub-parsec and kpc-scale probes of a PDLA.
643. QSO low-z Ly{alpha} absorbers
ID:
ivo://CDS.VizieR/J/ApJ/508/200
Title:
QSO low-z Ly{alpha} absorbers
Short Name:
J/ApJ/508/200
Date:
21 Oct 2021
Publisher:
CDS
Description:
To study the nature of low-z Ly{alpha} absorbers in the spectra of QSOs, we have obtained high signal-to-noise ratio (S/N) UV spectra of H1821+643 (z_em_=0.297) and PG 1116+215 (z_em_=0.177) with the Goddard High-Resolution Spectrograph on the Hubble Space Telescope.
644. QSO luminosity function at z~4
ID:
ivo://CDS.VizieR/J/ApJ/710/1498
Title:
QSO luminosity function at z~4
Short Name:
J/ApJ/710/1498
Date:
21 Oct 2021
Publisher:
CDS
Description:
The evolution of the quasar luminosity function (QLF) is one of the basic cosmological measures providing insight into structure formation and mass assembly in the universe. We have conducted a spectroscopic survey to find faint quasars (-26.0<M_1450_<-22.0) at redshifts z=3.8-5.2 in order to measure the faint end of the QLF at these early times. Using available optical imaging data from portions of the NOAO Deep Wide-Field Survey and the Deep Lens Survey, we have color-selected quasar candidates in a total area of 3.76deg^2^. Thirty candidates have R<=23mag. We conducted spectroscopic follow-up for 28 of our candidates and found 23 QSOs, 21 of which are reported here for the first time, in the 3.74<z<5.06 redshift range.
645. QSO MgII absorption line systems
ID:
ivo://CDS.VizieR/J/AJ/106/848
Title:
QSO MgII absorption line systems
Short Name:
J/AJ/106/848
Date:
21 Oct 2021
Publisher:
CDS
Description:
The results of a large R-band imaging survey of 71 bright (m(V)<18) quasars are presented. The quasars were chosen from published samples which have intermediate resolution optical spectroscopy available, so the presence of low redshift Mg II absorption lines can be determined. We have searched our data for galaxies close to the line-of-sight to the quasars, which we might be able to identify with the absorption systems. We find a high coincidence between galaxies very near the line-of-sight and quasars showing absorption systems in their spectra, a result consistent with other studies. These galaxies have a mean luminosity of 0.5L_star_ (assuming they lie at the absorption redshift). The distribution of impact parameters between the galaxies and the quasars extends with a flat distribution to large radii (>30h^-1^kpc). This suggests that the absorption systems may not be gravitationally bound to the observed galaxies, but may be part of larger extended systems. We also find a significant number of galaxies near the line-of-sight to the quasar where no absorption is seen in the quasar spectrum. The selection of our quasars is unbiased with respect to galaxies near the line-of-sight, so we can compare the observed number of absorption systems to that predicted by a simple model with a constant covering factor in Mg II absorbing gas within a maximum radius of each detected galaxy. The model is consistent with a covering factor of unity, but allowing for incompleteness in the detection of galaxies, the covering factor is less than unity. The redshifts of the galaxies are required to confirm this result.
646. QSO 2237+0305 photometry and light curves
ID:
ivo://CDS.VizieR/J/A+A/637/A89
Title:
QSO 2237+0305 photometry and light curves
Short Name:
J/A+A/637/A89
Date:
21 Oct 2021
Publisher:
CDS
Description:
Quasar microlensing offers a unique opportunity to resolve tiny sources in distant active galactic nuclei and study compact object populations in lensing galaxies. We therefore searched for microlensing-induced variability of the gravitationally lensed quasar QSO 2237+0305 (Einstein Cross) using 4374 optical frames taken with the 2.0m Liverpool Telescope and the 1.5m Maidanak Telescope. These gVrRI frames over the 2006-2019 period were homogeneously processed to generate accurate long-term multi-band light curves of the four quasar images A-D. Through difference light curves, we found strong microlensing signatures. We then focused on the analytical modelling of two putative caustic-crossing events in image C, finding compelling evidence that this image experienced a double caustic crossing. Additionally, our overall results indicate that a standard accretion disc accounts reasonably well for the brightness profile of UV continuum emission sources and for the growth in source radius when the emission wavelength increases: R_{lambda}_{prop.to}{lambda}^{alpha}^, {alpha}=1.33+/-0.09. However, we caution that numerical microlensing simulations are required before firm conclusions can be reached on the UV emission scenario because the VRI-band monitoring during the first caustic crossing and one of our two {alpha} indicators lead to a few good solutions with {alpha}~~1.
647. QSO properties from SDSS-DR7
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.
648. QSOs and RR Lyrae in Pan-STARRS1 3{pi} Data
ID:
ivo://CDS.VizieR/J/ApJ/817/73
Title:
QSOs and RR Lyrae in Pan-STARRS1 3{pi} Data
Short Name:
J/ApJ/817/73
Date:
21 Oct 2021
Publisher:
CDS
Description:
In area and depth, the Pan-STARRS1 (PS1) 3{pi} survey is unique among many-epoch, multi-band surveys and has enormous potential for the all-sky identification of variable sources. PS1 has observed the sky typically seven times in each of its five bands (grizy) over 3.5 years, but unlike SDSS, not simultaneously across the bands. We developed a new approach for quantifying statistical properties of non-simultaneous, sparse, multi-color light curves through light curve structure functions, effectively turning PS1 into a {sim}35-epoch survey. We use this approach to estimate variability amplitudes and timescales for point sources brighter than r_P1_=21.5 mag in the survey. On this basis we provide a catalog of all likely variable point sources and likely QSOs in PS1.
649. QSOs at z~6 spectral cubes
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.
650. QSOs CaII absorbers
ID:
ivo://CDS.VizieR/J/A+A/528/A12
Title:
QSOs CaII absorbers
Short Name:
J/A+A/528/A12
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a systematic study of weak intervening CaII absorbers at low redshift (z<0.5), based on the analysis of archival high-resolution (R>=45000) optical spectra of 304 quasars and active galactic nuclei observed with VLT/UVES. Along a total redshift path of {DELTA}z~~100 we detected 23 intervening CaII absorbers in both the CaII H & K lines, with rest frame equivalent widths W_r,3934_=15-799m{AA} and column densities logN(CaII)=11.25-13.04 (obtained by fitting Voigt-profile components).