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Start Over Subject quasars Validation Level 2
871. SMARTS & Euler R-band monitoring of WFI J2033-4723
ID:
ivo://CDS.VizieR/J/ApJ/869/106
Title:
SMARTS & Euler R-band monitoring of WFI J2033-4723
Short Name:
J/ApJ/869/106
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present 13 seasons of R-band photometry of the quadruply lensed quasar WFI J2033-4723 from the 1.3m SMARTS telescope at CTIO and the 1.2m Euler Swiss Telescope at La Silla, in which we detect microlensing variability of ~0.2mag on a timescale of ~6yrs. Using a Bayesian Monte Carlo technique, we analyze the microlensing signal to obtain a measurement of the size of this system's accretion disk of log(r_s_/cm)=15.86_-0.27_^+0.25^ at {lambda}_rest_=2481{AA}, assuming a 60{deg} inclination angle. We confirm previous measurements of the BC and AB time delays, and we obtain a tentative measurement of the delay between the closely spaced A1 and A2 images of {Delta}t_A1A2_=t_A1_-t_A2_=-3.9_-2.2_^+3.4^d. We conclude with an update to the Quasar Accretion Disk Size-Black Hole Mass Relation, in which we confirm that the accretion disk size predictions from simple thin disk theory are too small.
872. SMC AGN in XMM-Newton
ID:
ivo://CDS.VizieR/J/A+A/622/A29
Title:
SMC AGN in XMM-Newton
Short Name:
J/A+A/622/A29
Date:
21 Oct 2021
Publisher:
CDS
Description:
Finding active galactic nuclei (AGN) behind the Magellanic Clouds (MCs) is difficult because of the high stellar density in these fields. Although the first AGN behind the Small Magellanic Cloud (SMC) were reported in the 1980s, it is only recently that the number of AGN known behind the SMC has increased by several orders of magnitude. The mid-infrared colour selection technique has proven to be an efficient means of identifying AGN, especially obscured sources. The X-ray regime is complementary in this regard and we use XMM-Newton observations to support the identification of AGN behind the SMC. We present a catalogue of AGN behind the SMC by correlating an updated X-ray point-source catalogue from our XMM-Newton survey of the SMC with previously identified AGN from the literature as well as a list of candidates obtained from the ALLWISE mid-infrared colour-selection criterion. We studied the properties of the sample with respect to their redshifts, luminosities, and X-ray spectral characteristics. We also identified the near-infrared counterpart of the sources from the VISTA observations. The redshift and luminosity distributions of the sample (where known) indicate that we detect sources ranging from nearby Seyfert galaxies to distant and obscured quasars. The X-ray hardness ratios are compatible with those typically expected for AGN, and the VISTA colours and variability are also consistent with AGN. A positive correlation was observed between the integrated X-ray flux (0.2-12keV) and the ALLWISE and VISTA magnitudes. We further present a sample of new candidate AGN and candidates for obscured AGN. Together these make an interesting subset for further follow-up studies. An initial spectroscopic follow-up of 6 out of the 81 new candidates showed that all six sources are active galaxies, although two have narrow emission lines.
873. S5 0716+714 microvariability observation
ID:
ivo://CDS.VizieR/J/A+A/558/A92
Title:
S5 0716+714 microvariability observation
Short Name:
J/A+A/558/A92
Date:
21 Oct 2021
Publisher:
CDS
Description:
The international whole earth blazar telescope (WEBT) consortium planned and carried out three days of intensive micro-variability observations of S5 0716+714 from February 22, 2009 to February 25, 2009. This object was chosen due to its bright apparent magnitude range, its high declination, and its very large duty cycle for micro-variations. We report here on the long continuous optical micro-variability light curve of 0716+714 obtained during the multi-site observing campaign during which the Blazar showed almost constant variability over a 0.5 magnitude range. The resulting light curve is presented here for the first time. Observations from participating observatories were corrected for instrumental differences and combined to construct the overall smoothed light curve. Thirty-six observatories in sixteen countries participated in this continuous monitoring program and twenty of them submitted data for compilation into a continuous light curve. The light curve was analyzed using several techniques including Fourier transform, Wavelet and noise analysis techniques. Those results led us to model the light curve by attributing the variations to a series of synchrotron pulses.
874. SNU bright quasar survey (SNUQSO)
ID:
ivo://CDS.VizieR/J/ApJS/175/116
Title:
SNU bright quasar survey (SNUQSO)
Short Name:
J/ApJS/175/116
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present results from the first phase of the Seoul National University Bright Quasar Survey in Optical (SNUQSO) as well as its basic observational setup. Previous and current large-area surveys have been successful in identifying many quasars, but they could have missed bright quasars due to their survey design. In order to help complete the census of bright quasars, we have performed spectroscopic observations of new bright quasar candidates selected from various methods based on optical colors, near-infrared colors, radio, and X-ray data. In 2005/2006, we observed 55 bright quasar candidates using the Bohyunsan Optical Echelle Spectrograph (BOES) on the 1.8m telescope at the Bohyunsan Optical Astronomy Observatory in Korea. We identify 14 quasars/Seyferts from our observation, including an optically bright quasar with i=14.98mag at z=0.092 (SDSS J003236.59-091026.2). Non-quasar/Seyfert objects are found to be mostly stars, among which there are five M-type stars and one cataclysmic variable. Our result shows that there still exist bright quasars to be discovered. However, at the same time, we conclude that finding new bright quasars in high Galactic latitude regions is very challenging and that the existing compilation of optically bright quasars is nearly complete in the northern hemisphere.
875. Soft X-Ray-Selected AGNs complete sample
ID:
ivo://CDS.VizieR/J/AJ/127/156
Title:
Soft X-Ray-Selected AGNs complete sample
Short Name:
J/AJ/127/156
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the optical spectra and simple statistical analysis for a complete sample of 110 soft X-ray-selected AGNs. About half of the sources are narrow-line Seyfert 1 galaxies (NLS1's), which have the steepest X-ray spectra, the strongest Fe II emission, and slightly weaker [O III] {lambda}5007 emission than broad-line Seyfert 1's (BLS1's). Kolmogorov-Smirnov tests show that NLS1's and BLS1's have clearly different distributions of the X-ray spectral slope {alpha}_X_, X-ray short-term variability, and Fe II equivalent widths and luminosity and Fe II/H{beta} ratios.
876. Spatial variation in fine-structure constant
ID:
ivo://CDS.VizieR/J/MNRAS/422/3370
Title:
Spatial variation in fine-structure constant
Short Name:
J/MNRAS/422/3370
Date:
21 Oct 2021
Publisher:
CDS
Description:
Quasar absorption lines provide a precise test of whether the fine-structure constant, {alpha}, is the same in different places and through cosmological time. We present a new analysis of a large sample of quasar absorption-line spectra obtained using the Ultraviolet and Visual Echelle Spectrograph (UVES) on the Very Large Telescope (VLT) in Chile. We apply the many-multiplet method to derive values of {DELTA}{alpha}/{alpha}==({alpha}z-{alpha}0)/{alpha}0 from 154 absorbers, and combine these values with 141 values from previous observations at the Keck Observatory in Hawaii.
877. Spectral catalog of BeppoSAX blazars
ID:
ivo://CDS.VizieR/J/A+A/433/1163
Title:
Spectral catalog of BeppoSAX blazars
Short Name:
J/A+A/433/1163
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a spectral catalog for blazars based on the BeppoSAX archive. The sample includes 44 High-energy peaked BL Lacs (HBLs), 14 Low-energy peaked BL Lacs (LBLs), and 28 Flat Spectrum Radio Quasars (FSRQs). A total of 168 LECS, MECS, and PDS spectra were analyzed, corresponding to observations taken in the period 1996-2002. The 0.1-50keV continuum of LBLs and FSRQs is generally fitted by a single power law with Galactic column density.
878. Spectral & environment properties of z~2 QSO pairs
ID:
ivo://CDS.VizieR/J/ApJ/860/41
Title:
Spectral & environment properties of z~2 QSO pairs
Short Name:
J/ApJ/860/41
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the first results from our survey of intervening and proximate Lyman limit systems (LLSs) at z~2.0-2.5 using the Wide Field Camera 3 on board the Hubble Space Telescope. The quasars in our sample are projected pairs with proper transverse separations R_{perp}_<=150kpc and line-of- sight velocity separations <~11000km/s. We construct a stacked ultraviolet (rest-frame wavelengths 700-2000{AA}) spectrum of pairs corrected for the intervening Lyman forest and Lyman continuum absorption. The observed spectral composite presents a moderate flux excess for the most prominent broad emission lines, a ~30% decrease in flux at {lambda}=800-900{AA} compared to a stack of brighter quasars not in pairs at similar redshifts, and lower values of the mean free path of the HI ionizing radiation for pairs ({lambda}_mfp_^912^=140.7+/-20.2h_70_^-1^Mpc) compared to single quasars ({lambda}_mfp_^912^=213.8+/-28h_70_^-1^Mpc) at the average redshift z~2.44. From the modeling of LLS absorption in these pairs, we find a higher (~20%) incidence of proximate LLSs with logN_HI_>=17.2 at {delta}v<5000km/s compared to single quasars (~6%). These two rates are different at the 5{sigma} level. Moreover, we find that optically thick absorbers are equally shared between foreground and background quasars. Based on these pieces of evidence, we conclude that there is a moderate excess of gas-absorbing Lyman continuum photons in our closely projected quasar pairs compared to single quasars. We argue that this gas arises mostly within large-scale structures or partially neutral regions inside the dark matter halos where these close pairs reside.
879. Spectra of 28 intermediate redshift quasars
ID:
ivo://CDS.VizieR/J/A+A/608/A122
Title:
Spectra of 28 intermediate redshift quasars
Short Name:
J/A+A/608/A122
Date:
21 Oct 2021
Publisher:
CDS
Description:
Broad emission lines in quasars enable us to "resolve" structure and kinematics of the broad-line emitting region (BLR) thought to involve an accretion disk feeding a supermassive black hole. Interpretation of broad line measures within the 4DE1 formalism simplifies the apparent confusion among such data by contrasting and unifying properties of so-called high and low accreting Population A and B sources. H-beta serves as an estimator of black hole mass, Eddington ratio and source rest frame; the latter being a valuable input for CIV 1549 studies which allow us to isolate the blueshifted wind component. Optical and HST-UV spectra yield H-beta and CIV 1549 spectra for low-luminosity sources while VLT-ISAAC and FORS and TNG-LRS provide spectra for high-luminosity sources. New high-S/N data for CIV in high-luminosity quasars are presented here for comparison with the other previously published data. Comparison of H-beta and CIV 1549 profile widths/shifts indicates that much of the emission from the two lines arise in regions with different structure and kinematics. Covering a wide range of luminosity and redshift shows evidence for a correlation between CIV 1549 blueshift and source Eddington ratio, with a weaker trend with source luminosity (similar amplitude outflows are seen over four of the five dex luminosity ranges in our combined samples). At low luminosity (z<0.7) only Population A sources show evidence for a significant outflow while at high luminosity the outflow signature begins to appear in Population B quasars as well.
880. Spectra of lensed QSO PSOJ0147
ID:
ivo://CDS.VizieR/J/A+A/605/L8
Title:
Spectra of lensed QSO PSOJ0147
Short Name:
J/A+A/605/L8
Date:
21 Oct 2021
Publisher:
CDS
Description:
The gravitational lensing time delay method provides a one-step determination of the Hubble constant (H0) with an uncertainty level on par with the cosmic distance ladder method. However, to further investigate the nature of the dark energy, a H0 estimate down to 1% level is greatly needed. This requires dozens of strongly lensed quasars that are yet to be delivered by ongoing and forthcoming all-sky surveys. In this work we aim to determine the spectroscopic redshift of PSOJ0147, the first strongly lensed quasar candidate found in the Pan-STARRS survey. The main goal of our work is to derive an accurate redshift estimate of the background quasar for cosmography. To obtain timely spectroscopically follow-up, we took advantage of the fast-track service programme that is carried out by the Nordic Optical Telescope. Using a grism covering 3200-9600{AA}, we identified prominent emission line features, such as Ly{alpha}, NV, OI, CII, SiIV, CIV, and [CIII] in the spectra of the background quasar of the PSOJ0147 lens system. This enables us to determine accurately the redshift of the background quasar. The spectrum of the background quasar exhibits prominent absorption features bluewards of the strong emission lines, such as Ly{alpha}, NV, and CIV. These blue absorption lines indicate that the background source is a broad absorption line (BAL) quasar. Unfortunately, the BAL features hamper an accurate determination of redshift using the above-mentioned strong emission lines. Nevertheless, we are able to determine a redshift of 2.341+/-0.001 from three of the four lensed quasar images with the clean forbidden line [CIII]. In addition, we also derive a maximum outflow velocity of ~9800km/s with the broad absorption features bluewards of the CIV emission line. This value of maximum outflow velocity is in good agreement with other BAL quasars.

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