Journal Article

Properties of X-ray-selected broad absorption-line quasars*

A. J. Blustin, T. Dwelly, M. J. Page, I. M. McHardy, N. Seymour, J. A. Kennea, N. S. Loaring, K. O. Mason and K. Sekiguchi

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 390, issue 3, pages 1229-1240
Published in print November 2008 | ISSN: 0035-8711
Published online October 2008 | e-ISSN: 1365-2966 | DOI:
Properties of X-ray-selected broad absorption-line quasars*

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Broad absorption-line quasars (commonly termed BALQSOs) contain the most dramatic examples of active galactic nucleus (AGN) driven winds. The high absorbing columns in these winds, ∼1024cm−2, ensure that BALQSOs are generally X-ray faint. This high X-ray absorption means that almost all BALQSOs have been discovered through optical surveys, and so what little we know about their X-ray properties is derived from very bright optically selected sources. A small number of X-ray-selected BALQSOs (XBALQSOs) have, however, recently been found in deep X-ray survey fields. In this paper we investigate the X-ray and rest-frame ultraviolet (UV) properties of five XBALQSOs for which we have obtained XMM–Newton EPIC X-ray spectra and deep optical imaging and spectroscopy. We find that, although the XBALQSOs have an αox steeper by ∼0.5 than normal QSOs, their median αox is nevertheless flatter by 0.30 than that of a comparable sample of optically selected BALQSOs (OBALQSOs). We rule out the possibility that the higher X-ray to optical flux ratio is due to intrinsic optical extinction. We find that the amount of X-ray and UV absorption due to the wind in XBALQSOs is similar, or perhaps greater than, the corresponding wind absorption in OBALQSOs, so the flatter αox cannot be a result of weaker wind absorption. We conclude that these XBALQSOs have intrinsically higher X-ray to optical flux ratios than the OBALQSO sample with which we compare them.

Keywords: quasars: absorption lines; quasars: individual: CXOU J014546.9−043031; quasars: individual: CXOU J014517.1−042503; quasars: individual: CXOU J014553.9−043726; quasars: individual: CXOU J014546.5−042450; quasars: individual: CXOCDFS J033209.5−274807; ultraviolet: galaxies

Journal Article.  7557 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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