A Catalog of Broad Absorption Line Quasars from the Sloan Digital Sky Survey Early Data Release

Reichard, Timothy A.; Richards, Gordon T.; Schneider, Donald P.; Hall, Patrick B.; Tolea, Alin; Krolik, Julian H.; Tsvetanov, Z.; Berk, D. E. vanden; York, Donald G.; Knapp, G. R.; Gunn, James E.; Brinkmann, J.

doi:10.1086/368244

Cited by 140 publications

(149 citation statements)

References 46 publications

(70 reference statements)

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“…Recently, Reichard et al (2003) made a similar analysis with a much larger sample (224 BAL QSOs and 892 non-BAL QSOs) drawn from the SDSS EDR (Sloan Digital Sky Survey Early Data Release, Stoughton et al 2002), which essentially confirms the results of W91: there are no significant differences between emission line properties of BAL QSOs and non-BAL QSOs, except a noticeable enhancement of N  emission in BAL QSOs. Also, the continua of the BAL QSOs are redder (Reichard et al 2003), especially for those objects with low ionization absorption lines. This is possibly due to a larger dust content (Sprayberry & Foltz 1992;Yamamoto & Vansevicius 1999).…”

Section: Introductionsupporting

confidence: 58%

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Polarization properties of broad absorption line QSOs: New statistical clues

Lamy

Hutsemékers

2004

A&A

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Abstract.We report the results of several statistical tests performed on a large sample of 139 broad absorption line (BAL) QSOs with good quality optical spectra and/or optical polarization data. Correlations between ten optical indices and the polarization degree p 0 are systematically searched for. We find six significant non-trivial correlations. In order to identify the most important correlations, we perform a principal component analysis with a sample of 30 BAL QSOs and eight quantities (including p 0 ). Most of the variance (∼57%) in the data is contained in two principal components called PC1 and PC2. PC1 is mainly dominated by the correlation between the balnicity index BI and the strength of the Fe  emission; it may be driven by the accretion rate of matter onto the central compact object. The variance in PC2 is essentially due to the anti-correlation between p 0 and the detachment index DI, indicating that BAL QSOs with P Cygni profiles (DI ) are usually more polarized than those objects with C  absorption troughs well detached from the corresponding emission lines (DI ). We show that PC2 may be related to the orientation of the BAL QSOs with respect to the line of sight. We also present new spectropolarimetric observations of six BAL QSOs. By adding spectropolarimetric data from the literature, we build a sample of 21 BAL QSOs for which we define four spectropolarimetric indices describing the polarization properties of the absorption and emission lines. We find that the polarization of the C ] emission line is systematically higher than the polarization of the C  emission line, and that the highest polarization in the troughs is correlated to the balnicity index. Another important result emerging from the statistical tests performed on this spectropolarimetric sample is a possible anti-correlation between the detachment index and a quantity SI which measures the ratio of the depths of the C  absorption in the polarized flux and in the total flux. This correlation indicates that in BAL QSOs with P cygni profiles, the BAL troughs in the polarized flux are nearly as deep as in the total flux while, in BAL QSOs with detached absorptions, the BAL troughs in the polarized flux are much weaker than in the total flux. We show that our main results may be explained in the framework of a "two-component" wind model which is a natural extension of the classical wind-from-disk models. In this model, the broad absorption occurs in a dense equatorial wind emerging from the accretion disk, while scattering and polarization mainly take place in a polar region. The orientation relative to the observer drives the correlations p 0 -DI and DI -SI. While most of our observations can be explained within this framework, there are also several indications that other polarization mechanisms, and more particularly resonance scattering, may also be at work.

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Section: Introductionsupporting

confidence: 58%

“…About 10 to 20% of optically-selected QSOs exhibit broad absorption lines (BAL) in the resonance lines of highly ionized species such as N  λ 1240, C  λ 1549 or Si  λ 1397 (Hewett & Foltz 2003;Tolea et al 2002;Reichard et al 2003).…”

Section: Introductionmentioning

confidence: 99%

Polarization properties of broad absorption line QSOs: New statistical clues

Lamy

Hutsemékers

2004

A&A

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“…There exists a distribution of slopes for quasar continua and when using the composite presented here, the intrinsic slope of the modeled quasar is highly degenerate with the amount of dust inferred (Reichard et al 2003). Since attenuation by dust is stronger at shorter wavelengths, extinction introduces a curvature in the spectrum, which is separate from a pure change in slope, see Krawczyk et al (2015) for a discussion of red vs. reddened quasars.…”

Section: Applicability Of the Compositementioning

confidence: 87%

An X-Shooter composite of bright 1 <z< 2 quasars from UV to infrared

Selsing

Fynbo

Christensen

et al. 2015

A&A

160

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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 nearinfrared (NIR) light, which ensures that the composite spectrum covers the full rest-frame range from Lyβ to 11 350 Å without any significant host contamination. Assuming a power-law continuum for the composite we find a spectral slope of α λ = 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 [Fe II] blends) or by intrinsic host galaxy emission. Finally, we demonstrate the application of the QSO composite spectrum for evaluating the reddening in other QSOs.

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“…Also, broad-absorption line (BAL) AGN display outflowing gas with velocities of a few 1000 km s −1 in UV absorption lines like [C iv] and Mg ii (e.g. Reichard et al 2003; Trump et al 2006;Gibson et al 2009). The extent of the outflows is usually not directly constrained from those observation due to a lack of spatial resolution.…”

Section: Introductionmentioning

confidence: 99%

Large-scale outflows in luminous QSOs revisited

Husemann

Scharwächter

Bennert

et al. 2016

A&A

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Context. Feedback from active galactic nuclei (AGN) is thought to play an important role in quenching star formation in galaxies. However, the efficiency with which AGN dissipate their radiative energy into the ambient medium remains strongly debated. Aims. Enormous observational efforts have been made to constrain the energetics of AGN feedback by mapping the kinematics of the ionized gas on kpc scale. We study how the observed kinematics and inferred energetics are affected by beam smearing of a bright unresolved narrow-line region (NLR) due to seeing. Methods. We re-analyse optical integral-field spectroscopy of a sample of twelve luminous unobscured quasi-stellar objects (QSOs) (0.4 < z < 0.7) previously presented in the literature. The point-spread function (PSF) for the observations is directly obtained from the light distribution of the broad Hβ line component. Therefore, we are able to compare the ionized gas kinematics and derived energetics of the total, truly spatially extended, and unresolved [O iii] emission. Results. We find that the spatially resolved [O iii] line width on kpc scales is significantly narrower than the one before PSF deblending. The extended NLRs (ENLRs) appear intrinsically offset from the QSO position or more elongated which can be interpreted in favour of a conical outflow on large scales while a spherical geometry cannot be ruled out for the unresolved NLR. We find that the kinetic power at 5 kpc distance based on a spherical model is reduced by two orders of magnitude for a conical outflow and one order of magnitude for the unresolved NLR after PSF deblending. This reduced kinetic power corresponds to only 0.01−0.1 per cent of the bolometric AGN luminosity. This is smaller than the 5−10% feedback efficiency required by some cosmological simulations to reproduce the massive galaxy population. The injected momentum fluxes are close or below the simple radiation-pressure limit L bol /c for the conical outflow model for the NLR and ENLR when beam smearing is considered. Conclusions. Integral-field spectroscopy is a powerful tool to investigate the energetics of AGN outflows, but the impact of beam smearing has to be taken into account in the high contrast regime of QSOs. For the majority of observations in the literature, this has not been addressed carefully so that the incidence and energetics of presumed kpc-scale AGN-driven outflows still remain an unsolved issue, from an observational perspective.

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A Catalog of Broad Absorption Line Quasars from the Sloan Digital Sky Survey Early Data Release

Cited by 140 publications

References 46 publications

Polarization properties of broad absorption line QSOs: New statistical clues

Polarization properties of broad absorption line QSOs: New statistical clues

An X-Shooter composite of bright 1 <z< 2 quasars from UV to infrared

Large-scale outflows in luminous QSOs revisited

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