Continuum and Emission-Line Properties of Broad Absorption Line Quasars

By T. Reichard, Gordon Richards, P. B. Hall, D. Schneider, D. V. vanden Berk, Xiaohui Fan, D. York, G. Knapp, J. Brinkmann. 2003

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We investigate the continuum and emission-line properties of 224 broad absorption line quasars (BALQSOs) with 0.9 ≲ z ≲ 4.4 drawn from the Sloan Digital Sky Survey Early Data Release, which contains 3814 bona fide quasars. We find that low-ionization BALQSOs (LoBALs) are significantly reddened as compared with normal quasars, in agreement with previous work. High-ionization BALQSOs (HiBALs) are also more reddened than the average non-BALQSO. Assuming SMC-like dust reddening at the quasar redshift, the amount of reddening needed to explain HiBALs is E(B-V) ∼ 0.023 and LoBALs is E(B-V) ∼ 0.077 (compared with the ensemble average of the entire quasar sample). We find that there are differences in the emission-line properties between the average HiBAL, LoBAL, and non-BAL quasar. These differences, along with differences in the absorption-line troughs, may be related to intrinsic quasar properties such as the slope of the intrinsic (unreddened) continuum; more extreme absorption properties are correlated with bluer intrinsic continua. Despite the differences among BALQSO subtypes and non-BALQSOs, BALQSOs appear to be drawn from the same parent population as non-BALQSOs when both are selected by their UV/optical properties. We find that the overall fraction of traditionally defined BALQSOs, after correcting for color-dependent selection effects due to different SEDs of BALQSOs and non-BALQSOs, is 13.4% ± 1.2% and shows no significant redshift dependence for 1.7 ≤ z ≤ 3.45. After a rough completeness correction for the effects of dust extinction, we find that approximately one in every six quasars is a BALQSO.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/7c31595308bc2827f39954c7b787391873133f0c

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Citations in the corpus

A Cosmological Framework for the Co-Evolution of Quasars, Supermassive Black Holes, and Elliptical Galaxies. II. Formation of Red Ellipticals (2007, background): “…to quasars see highly energetic (kseveral 103 km s 1) broad absorption line (BAL) outflows, and it is likely that all bright quasars exhibit some such BALs (although they may not be visible owing to geometric effects; Reichard et al. 2003; Elvis 2000; Gallagher et al. 2006; Priddey et al. 2007).”
A strong redshift dependence of the broad absorption line quasar fraction (2010, methodology): “The observed C iv BALQSO fraction has been variously calculated as, among other measurements, 15±3 (Hewett & Foltz 2003), 14.0±1.0 (Reichard et al. 2003b), 12.5 (Scaringi et al. 2009), and 13.3±0.6 per cent (G09).”
Dust Reddening in Sloan Digital Sky Survey Quasars (2004, methodology): “The geometric mean of the spectra was used, which preserves input power-law slopes (and EB V values, if all dust is at the quasar redshifts and the curvature in the reddening law is the same in all objects; see the Appendix to Reichard et al. 2003).”
Soft X-Ray and Ultraviolet Emission Relations in Optically Selected AGN Samples (2005, background): “We expect there to be 8 more HiBAL and P1 more LoBAL AGNs (for a typical LoBAL :HiBAL ratio of 1:10; Reichard et al. 2003) that we are unable to identify because of a lack of spectral coverage in the C iv orMg ii regions.”
Constraining the Evolution of the Ionizing Background and the Epoch of Reionization with z ∼ 6 Quasars. II. A Sample of 19 Quasars (2005, background): “Note that the fraction of BAL quasars at z < 4 is ∼ 15% in color-selected samples (e.g. Reichard et al. 2003).”
Average extinction curves and relative abundances for quasi-stellar object absorption-line systems at 1 ≤zabs < 2 (2006, background): “That BAL QSOs may be contributing is also indicated by the fact that the composite spectrumobtained by Malhotra is quite red, a common feature of BAL spectra (Reichard et al. 2003b).”
A Catalog of Broad Absorption Line Quasars from the Sloan Digital Sky Survey Early Data Release (2003, methodology): “…report a corrected BALQSO fraction of 22 ± 4% for their sample of 42 bright (BJ < 19) quasars, Tolea, Krolik & Tsvetanov (2002) estimate a fraction of ∼ 15% from their sample of 116 quasars, and Reichard et al. (2003b) estimate a corrected fraction of 15.9±1.4% for a sample of 224 quasars with i .”
A CATALOG OF BROAD ABSORPTION LINE QUASARS IN SLOAN DIGITAL SKY SURVEY DATA RELEASE 5 (2008, background): “If the emission in the line wings or line emission from other ions differs between BALs and non-BALs (e.g., Reichard et al. 2003), we would not be sensitive to these effects.”
The evolution of the broad-line region among SDSS quasars (2005, methodology): “Indeed Reichard et al. (2003b) found 224 BAL quasars among 3814 quasars in the SDSS early data release (EDR; Stoughton et al. 2002).”
UNIFICATION OF LUMINOUS TYPE 1 QUASARS THROUGH C iv EMISSION (2010, result): “These findings are quite consistent with our results from Reichard et al. (2003) where it was found that BALQSOs have larger than average blueshifts and smaller than average C iv EQWs (and bluer colors after correcting for dust reddening), with LoBALs having the most extreme properties—by virtue of…”
Biases in Virial Black Hole Masses: An SDSS Perspective (2007, background): “First, BALs in general are more reddened than nonBALs (e.g., Reichard et al. 2003), affecting the bolometric luminosity estimates.”
Black Hole Masses and Enrichment of z ~ 6 SDSS Quasars (2007, background): “At low and intermediate redshift, BAL QSOs account for ∼15% of the whole quasar population (Reichard et al. 2003; Hewett & Foltz 2003), but Maiolino et al. (2004a) find four BAL QSOs among the eight QSOs at 4.9 < z < 6.4 that they observe, suggesting that the most distant quasars are surrounded by…”
An Exploratory Chandra Survey of a Well-defined Sample of 35 Large Bright Quasar Survey Broad Absorption Line Quasars (2006, methodology): “However, in an analysis of 224 SDSS BAL quasars, Reichard et al. (2003) found that BAL quasars are in general mildly dust-reddened, with an average E(B − V ) of 0.023 and 0.077 for highionization (HiBAL) and LoBAL quasars, respectively.”
The Intrinsic Fraction of Broad Absorption Line Quasars (2008, methodology): “However, despite these differences, BALQSOs and non-BAL QSOs appear to be drawn from the same parent population (Reichard et al. 2003).”