PG 1254+047: An Intrinsically X‐Ray Weak, Heavily Absorbed Broad Absorption Line Quasar?

Sabra, B.; Hamann, Fred

doi:10.1086/324043

Cited by 30 publications

(36 citation statements)

References 29 publications

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“…At X‐ray energies most BAL quasars are ‘X‐ray weak’, a property explained by line‐of‐sight absorption in moderately ionized gas with column densities up to N H = 10 23 cm −2 (e.g. Hamann 1998; Sabra, & Hamann 2001; Gallagher et al 2002). Crucially, these observations have not revealed whether the X‐ray absorbing column is moving or stationary.…”

Section: Discussionmentioning

confidence: 99%

Evidence of a high-velocity ionized outflow in a second narrow-line quasar PG 0844+349

Pounds

King

Page

et al. 2003

Monthly Notices of the Royal Astronomical Society

146

110

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Following the discovery of X‐ray absorption in a high‐velocity outflow from the bright quasar PG 1211 + 143 we have searched for similar features in XMM–Newton archival data of a second (high accretion rate) quasar PG 0844+349. Evidence is found for several faint absorption lines in both the EPIC and RGS spectra, whose most likely identification with resonance transitions in H‐like Fe, S and Ne implies an origin in highly ionized matter with an outflow velocity of order ∼0.2c. The line equivalent widths require a line‐of‐sight column density of NH∼ 4 × 1023 cm−2, at an ionization parameter of log ξ∼ 3.7. Assuming a radial outflow being driven by radiation pressure from the inner accretion disc, as suggested previously for PG 1211 + 143, the flow in PG 0844+349 is also likely to be optically thick, in this case within ∼25 Schwarzschild radii. Our analysis suggests that a high‐velocity, highly ionized outflow is likely to be a significant component in the mass and energy budgets of active galactic nuclei accreting at or above the Eddington rate.

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Section: Discussionmentioning

confidence: 99%

Evidence of a high-velocity ionized outflow in a second narrow-line quasar PG 0844+349

Pounds

King

Page

et al. 2003

Monthly Notices of the Royal Astronomical Society

146

110

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“…If the 1999 ASCA data are more representative, then PG 2112+059 might return to this emission level at any time. At least one BAL quasar, PG 1254+047, was argued to be intrinsically X-ray-weak in addition to suffering from heavy X-ray absorption (Sabra & Hamann 2001). Although the X-ray data quality in that particular case was poor (only $44 photons), it is quite possible that the strength of the X-ray continuum of that source varies as well.…”

Section: Iron Emissionmentioning

confidence: 99%

Dramatic X‐Ray Spectral Variability of the Broad Absorption Line Quasar PG 2112+059

Gallagher¹,

Brandt²,

Wills³

et al. 2004

ApJ

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With a 1999 ASCA observation, PG 2112+059 became notable as the first broad absorption line (BAL) quasar found to exhibit a typical radio-quiet quasar X-ray continuum underlying a large amount of intrinsic absorption. We present a recent Chandra ACIS-S3 observation of PG 2112+059 that demonstrates remarkable spectral and luminosity variability since that time. In addition to a decrease in the continuum normalization by a factor of $3.5, the absorption column density has apparently increased substantially, and a strong feature in the Fe K region has appeared. Concurrent Hubble Space Telescope (HST ) STIS data compared with archival HST data from earlier epochs show evidence for variability of the continuum (up to a factor of $1.7 in the ultraviolet), and in some absorption features of the C iv k1549 BAL since 1992; however, the O vi BAL structure is consistent with a 1995 observation. We also present evidence for Ly-O vi k1037.62 and Ly -N v k1242.80 line-locked absorption systems, supporting the assumption that ultraviolet line pressure is driving the BAL outflow. Whereas ultraviolet BALs typically exhibit only modest equivalent width variability over timescales of years, the dramatic X-ray variability of PG 2112+059 suggests that X-ray spectral variability studies of BAL quasars have great potential for probing the physics of quasar winds.

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“…In this scenario, a reflection‐dominated continuum originating in the accretion disc (caused by strong light bending) can also play an important role (see Schartel et al 2007, 2010; Gallo et al 2011). Finally, the observed weakness can be an intrinsic property due to a fundamentally distinct emission mechanism [Risaliti et al 2003; see also the case of PG 1254+047 (Sabra & Hamann 2001) and PHL 1811 (Leighly et al 2007)]. This last hypothesis implies different scenarios for the accretion disc.…”

Section: Introductionmentioning

confidence: 97%

XMM-Newton first X-ray detection of the low-ionization broad absorption line quasar PG 1700+518

Ballo

Piconcelli

Vignali

et al. 2011

Monthly Notices of the Royal Astronomical Society

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We report the first high‐energy detection of PG 1700+518, a well‐known low‐ionization broad absorption line quasar (quasi‐stellar object, QSO). Due to previous X‐ray non‐detection, it was classified as soft X‐ray weak QSO. We observed PG 1700+518 with XMM–Newton for about 60 ks divided in three exposures. The spectrum below 2 keV is very steep, Γ∼ 2.4–3.8, while at higher energies the extremely flat emission (photon index Γ∼ 0.15, when modelled with a power law) suggests the presence of strong absorption (NH, pl∼ 2 × 1023 cm−2, Γ fixed to 1.8) or a reflection‐dominated continuum. The broad‐band flux is consistent with previous non‐detection. Simultaneous European Photon Imaging Camera (EPIC) and Optical Monitor (OM) data confirm its X‐ray weakness (observedαox∼−2.2). The level of obscuration derived from the X‐ray spectra of PG 1700+518 cannot explain its soft X‐ray nuclear weakness unless a column density of NH≳ 2 × 1024 cm−2 is present.

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PG 1254+047: An Intrinsically X‐Ray Weak, Heavily Absorbed Broad Absorption Line Quasar?

Cited by 30 publications

References 29 publications

Evidence of a high-velocity ionized outflow in a second narrow-line quasar PG 0844+349

Evidence of a high-velocity ionized outflow in a second narrow-line quasar PG 0844+349

Dramatic X‐Ray Spectral Variability of the Broad Absorption Line Quasar PG 2112+059

XMM-Newton first X-ray detection of the low-ionization broad absorption line quasar PG 1700+518

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