Journal Article

Narrow associated quasi-stellar object absorbers: clustering, outflows and the line-of-sight proximity effect

Vivienne Wild, Guinevere Kauffmann, Simon White, Donald York, Matthew Lehnert, Timothy Heckman, Patrick B. Hall, Pushpa Khare, Britt Lundgren, Donald P. Schneider and Daniel Vanden Berk

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 388, issue 1, pages 227-241
Published in print July 2008 | ISSN: 0035-8711
Published online July 2008 | e-ISSN: 1365-2966 | DOI:
Narrow associated quasi-stellar object absorbers: clustering, outflows and the line-of-sight proximity effect

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Using data from the Sloan Digital Sky Survey data release 3 (SDSS DR3), we investigate how narrow (<700 km s−1) C iv and Mg ii quasar absorption-line systems are distributed around quasars. The C iv absorbers lie in the redshift range 1.6 < z < 4 and the Mg ii absorbers in the range 0.4 < z < 2.2. By correlating absorbers with quasars on different but neighbouring lines of sight, we measure the clustering of absorbers around quasars on comoving scales between 4 and 30 Mpc. The observed comoving correlation lengths are ro∼ 5h−1Mpc, similar to those observed for bright galaxies at these redshifts. Comparing correlations between absorbers and the quasars, in whose spectra they are identified, then implies: (i) that quasars destroy absorbers to comoving distances of ∼300 kpc (C iv) and ∼800 kpc (Mg ii) along their lines of sight; (ii) that ≳40 per cent of C iv absorbers within 3000 km s−1 of the quasi-stellar object are not a result of large-scale clustering but rather are directly associated with the quasar itself; (iii) that this intrinsic absorber population extends to outflow velocities of the order of 12 000 km s−1; (iv) that this outflow component is present in both radio-loud and radio-quiet quasars and (v) that a small high-velocity outflow component is also observed in the Mg ii population. We also find an indication that absorption systems within 3000 km s−1 are more abundant for radio-loud quasars than for radio-quiet quasars. This suggests either that radio-loud objects live in more massive haloes, or that their radio activity generates an additional low-velocity outflow, or both.

Keywords: accretion, accretion discs; galaxies: active; quasars: absorption lines; large-scale structure of Universe

Journal Article.  12383 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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