On the Fraction of Quasars with Outflows

Ganguly, R.; Brotherton, Michael S.

doi:10.1086/524106

Cited by 187 publications

(195 citation statements)

References 59 publications

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“…This supports previous suggestions that at least some narrower and broader absorption phenomena are physically related (e.g., Arav et al 1999;Gallagher et al 2002;Ganguly & Brotherton 2008;Misawa et al 2008). Flatter hard X-ray spectra observed for QSOs with mini-BAL and especially BAL absorption could be explained by ionized or partial-covering absorber models with high (N H 10 22 cm −2 ) effective column densities.…”

Section: Are Mini-bals Just Narrow Bals?supporting

confidence: 89%

“…The velocity-width distinction used to classify absorbers as BALs (width > 2000 km s −1 ), mini-BALs (intermediate widths), and narrow absorption lines (NALs; width < 500 km s −1 for C iv) is somewhat arbitrary; it has been suggested that BAL absorption is an extension of the same physical processes responsible for narrower absorption features observed in QSO spectra (e.g., Section 4.2.1 of Arav et al 1999;Ganguly & Brotherton 2008). Previous studies of BAL QSOs have found that their UV absorption properties are correlated with the relative X-ray brightness of these sources (e.g., Gallagher et al 2006), indicating a physical link between X-ray absorption and the acceleration of BAL outflows.…”

Section: A Continuum Of Absorber Properties?mentioning

confidence: 99%

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X-Ray Insights Into the Physics of Mini-Bal Quasar Outflows

Gibson

Brandt

Gallagher

et al. 2009

ApJ

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We examine the ultraviolet and X-ray properties of 256 radio-quiet Sloan Digital Sky Survey quasars (QSOs) observed in X-rays with Chandra and/or XMM-Newton in order to study the relationship between QSOs with broad C iv absorption lines (BALs; width > 2000 km s −1 ) and those with C iv mini-BALs (here defined to have widths of 1000-2000 km s −1 ). Our sample includes 42 BAL and 48 mini-BAL QSOs. The relative X-ray brightness and hard spectral slopes of the mini-BAL population are, on average, intermediate between those of BAL and non-BAL QSOs, as might be expected if narrower and broader absorption line outflows are physically related. However, a significant population of mini-BALs has outflow velocities higher than would be expected for BAL QSOs of the same relative X-ray brightness. Consistently strong X-ray absorption is apparently not required to accelerate at least some mini-BALs to high outflow velocities. Assuming the mini-BAL features are correctly attributed to intrinsic C iv absorption, we suggest that their observed properties may be explained if mini-BALs are "seeds" that can be accelerated to form BALs when sufficient X-ray shielding is present. We also examine several QSOs with broad C iv absorption that have been recently reported to be unusually X-ray bright. Such cases are frequently mini-BAL QSOs, which, as a population, are generally brighter in X-rays than BAL QSOs. Pointed XMM-Newton observations also suggest that these sources (or unresolved neighbors) may have been previously observed in a high-flux state.

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Section: Are Mini-bals Just Narrow Bals?supporting

confidence: 89%

Section: A Continuum Of Absorber Properties?mentioning

confidence: 99%

X-Ray Insights Into the Physics of Mini-Bal Quasar Outflows

Gibson

Brandt

Gallagher

et al. 2009

ApJ

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“…The doublet Mg + λλ2796,2803 is a low ionization line (LIL) that has long been thought to be produced in a dense optically thick region where at least part of the Balmer lines arise (Grandi & Phillips 1979;Netzer 1980). A possible complication is that Mgiiλ2800 is a resonance line and therefore often affected by broad (Ganguly & Brotherton 2008) and narrow absorption (Wild et al 2008). Several authors have attempted to define a relation between Mgiiλ2800 and Hβ to provide consistent M BH estimates from the two lines A89, page 2 of 16 (McLure & Jarvis 2002;Wang et al 2009;Shen & Liu 2012;Trakhtenbrot & Netzer 2012).…”

Section: Introductionmentioning

confidence: 99%

Is MgIIλ2800 a reliable virial broadening estimator for quasars?

Marziani

Sulentic

Plauchu-Frayn

et al. 2013

A&A

156

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Context. Broad Mgiiλ2800 and Hβ lines have emerged as the most reliable virial estimators of the black hole mass in quasars. Which is more reliable? Part of the challenge centers on comparing Mgiiλ2800 and Hβ line profiles in order to improve the ±1 dex M BH uncertainties inherent in single-epoch FWHM measures from noisy spectra. Aims. We compare Mgiiλ2800 and Hβ profile measures in the same sources and especially FWHM measures that provide the virial broadening estimator. Methods. We identify 680 bright Sloan Digital Sky Survey Data Release 7 quasars with spectra showing both Mgiiλ2800 and Hβ lines at redshift 0.4 ≤ z ≤ 0.75. The S/N of these spectra are high enough to allow binning in the "four-dimensional (4D) eigenvector 1" optical plane and construction of high S/N composite spectra. Results. We confirm that Mgiiλ2800 shows a profile that is ≈20% narrower as suggested in some previous studies. FWHM measures for Population B sources (i.e., with FWHM of Hβ larger than 4000 km s −1 ) are uncertain because they show complex profiles with at least two broad-line components involving a nearly unshifted broad and redshifted very-broad component. Only the broad component is likely to be a valid virial estimator. If Hβ and Mgiiλ2800 are not corrected for the very broad component then black hole mass M BH values for Population B sources will be systematically overestimated by up to Δ logM BH ≈ 0.3−0.4 dex. We suggest a simple correction that can be applied to the majority of sources. Mgiiλ2800 is the safer virial estimator for Population B sources because the centroid shifts with respect to rest frame are lower than for Hβ. In the broad and very broad component profile interpretation, this is a consequence of the lower very broad to broad component intensity ratio for Mgiiλ2800. Eigenvector-based studies show that effective discrimination of black hole mass and Eddington ratio at fixed redshift is not achieved via luminosity binning but rather by binning in a "4D eigenvector 1" context that reflects different broad line region geometry/kinematics probably driven by the Eddington ratio.

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“…Many AGNs show blueshifted absorption from outflowing matter (Ganguly & Brotherton 2008). Very broad absorption lines (BALs) corresponding to a wide variety of velocities are observed in luminous quasars.…”

Section: Introductionmentioning

confidence: 99%

Unusual quasars from the Sloan Digital Sky Survey selected by means of Kohonen self-organising maps

Meusinger¹,

Schalldach²,

Scholz³

et al. 2012

A&A

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Context. Large spectroscopic surveys have discovered very peculiar and hitherto unknown types of active galactic nuclei (AGN). Such rare objects may hold clues to the accretion history of the supermassive black holes at the centres of galaxies. Aims. We aim to create a sizeable sample of unusual quasars from the unprecedented spectroscopic database of the Sloan Digital Sky Survey (SDSS). Methods. We exploit the spectral archive of the SDSS Data Release 7 to select unusual quasar spectra. The selection method is based on a combination of the power of self-organising maps and the visual inspection of a huge number of spectra. Self-organising maps were applied to nearly 10 5 spectra classified as quasars at redshifts from z = 0.6 to 4.3 by the SDSS pipeline. Particular attention was paid to minimise possible contamination by rare peculiar stellar spectral types. All selected quasar spectra were individually studied to determine the object type and the redshift.Results. We present a catalogue of 1005 quasars with unusual spectra. These spectra are dominated by either broad absorption lines (BALs; 42%), unusual red continua (27%), weak emission lines (18%), or conspicuously strong optical and/or UV iron emission (11%). This large sample provides a useful resource for both studying properties and relations of/between different types of unusual quasars and selecting particularly interesting objects, even though the compilation is not aimed at completeness in a quantifiable sense. The spectra are grouped into six types for which composite spectra are constructed and mean properties are computed. Remarkably, all these types turn out to be on average more luminous than comparison samples of normal quasars after a statistical correction is made for intrinsic reddening (E(B − V) ≈ 0 to 0.4 for SMC-like extinction). Both the unusual BAL quasars and the strong iron emitters have significantly lower radio luminosities than normal quasars. We also confirm that strong BALs avoid the most radioluminous quasars. For 32 particularly interesting objects, individual spectra are presented. Among these objects are quasars with many narrow BAL troughs and one quasar where the continuum is strongly suppressed by overlapping BAL troughs across nearly the whole SDSS spectrum. Finally, we create a sample of quasars similar to the two "mysterious" objects discovered by Hall et al. (2002, ApJS, 141, 267) and briefly discuss the quasar properties and possible explanations of their highly peculiar spectra.

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On the Fraction of Quasars with Outflows

Cited by 187 publications

References 59 publications

X-Ray Insights Into the Physics of Mini-Bal Quasar Outflows

X-Ray Insights Into the Physics of Mini-Bal Quasar Outflows

Is MgIIλ2800 a reliable virial broadening estimator for quasars?

Unusual quasars from the Sloan Digital Sky Survey selected by means of Kohonen self-organising maps

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