Suzaku Observations of Near-Relativistic Outflows in the BAL Quasar APM 08279+5255 (original) (raw)
Related papers
2004
We present the results of an analysis of data from XMM-Newton and CHANDRA observations of the high luminosity narrow-line quasar PG 1404+226. We confirm a strong soft X-ray excess in the X-ray spectrum and we find rapid variability (a factor of two in about 5000 s). When the X-ray spectrum is fit with a two component model which includes a power-law and a blackbody component, we find that low energy absorption lines are required to fit the data. If we interpret these lines as due to highly ionized species of heavy elements in an outflowing accretion disk wind, an outflow velocity of ∼ 26000 km s −1 could be derived. One interesting feature of the present observation is the possible detection of variability in the absorption features: the absorption lines are visible only when the source is bright. From the upper limits of the equivalent widths (EW) of the absorption lines during the low flux states and also from the model independent pulse height ratios, we argue that the strength o...
A high-velocity narrow absorption line outflow in the quasar J212329.46 − 005052.9
Monthly Notices of the Royal Astronomical Society, 2010
We report on the discovery of a high-velocity narrow absorption line outflow in the redshift 2.3 quasar J212329.46-005052.9. Five distinct outflow systems are detected with velocity shifts from −9710 to −14,050 km s −1 and C iv λλ1548,1551 line widths of FWHM ≈ 62 to 164 km s −1 . This outflow is remarkable for having high speeds and a degree of ionization similar to broad absorption line (BAL) flows, but line widths roughly 100 times narrower than BALs and no apparent X-ray absorption. This is also, to our knowledge, the highest-velocity narrow absorption line system confirmed to be in a quasar outflow by all three indicators of line variability, smooth super-thermal line profiles and doublet ratios that require partial covering of the quasar continuum source. All five systems have stronger absorption in O vi λλ1032,1038 than C iv with no lower ionization metal lines detected. Their line variabilities also appear coordinated, with each system showing larger changes in C iv than O vi and line strength variations accompanied by nearly commensurate changes in the absorber covering fractions. The metallicity is approximately twice solar.
2005
We present the results of an analysis of data from XMM-Newton and CHANDRA observations of the high luminosity narrow-line quasar PG 1404+226. We confirm a strong soft X-ray excess in the X-ray spectrum and we find rapid variability (a factor of two in about 5000 s). When the X-ray spectrum is fit with a two component model which includes a power-law and a blackbody component, we find that low energy absorption lines are required to fit the data. If we interpret these lines as due to highly ionized species of heavy elements in an outflowing accretion disk wind, an outflow velocity of ∼ 26000 km s −1 could be derived. One interesting feature of the present observation is the possible detection of variability in the absorption features: the absorption lines are visible only when the source is bright. From the upper limits of the equivalent widths (EW) of the absorption lines during the low flux states and also from the model independent pulse height ratios, we argue that the strength of absorption is lower during the low flux states. This constraints the physical size of the absorbing medium within 100 Schwartzschild radius (R g) of the putative supermassive black hole. We also find a marginal evidence for a correlation between the strength of the absorption line and the X-ray luminosity.
Context. We have re-analyzed the X-ray spectra of the gravitational lensed high-redshift BAL QSO APM 08279+5255, observed with the XMM-Newton and Chandra observatories. Previous studies ) detected unusual, highly-ionized iron absorption features, but differed in their interpretation of these features, regarding the kinematical and ionization structure. Aims. We seek one physical model that can be successfully applied to both observations. Methods. For the first time we have performed detailed photoionization modeling on the X-ray spectrum of APM 08279+5255. Results. The absorbing gas in APM 08279+5255 can be represented by a two-absorbers model with column densities N H (1) ≈ 7×10 22 cm −2 , N H (2) ≈ 6 × 10 22 cm −2 , and ionization parameters log ξ(1) ≈ 1.5 and log ξ(2) ≈ 3, with one of them (the high-ionization component) outflowing at v ≈ 0.18(±0.01)c, carrying large amount of gas out of the system. We find that the Chandra spectrum of APM 08279+5255 requires the same Fe/O ratio overabundance (previously) indicated by the XMM-Newton observation, showing that both absorber components underwent similar chemical evolution and/or have similar origin.
We statistically study the physical properties of a sample of narrow absorption line (NAL) systems looking for empirical evidences to distinguish between intrinsic and intervening NALs without taking into account any a priori definition or velocity cutoff. We analyse the spectra of 100 quasars with 3.5 < z em < 4.5, observed with X-shooter/Very Large Telescope in the context of the XQ-100 Legacy Survey. We detect an ∼8σ excess in the C IV number density within 10 000 km s −1 of the quasar emission redshift with respect to the random occurrence of NALs. This excess does not show a dependence on the quasar bolometric luminosity and it is not due to the redshift evolution of NALs. It extends far beyond the standard 5000 km s −1 cutoff traditionally defined for associated absorption lines. We propose to modify this definition, extending the threshold to 10 000 km s −1 when weak absorbers (equivalent width < 0.2 Å) are also considered. We infer N V is the ion that better traces the effects of the quasar ionization field, offering the best statistical tool to identify intrinsic systems. Following this criterion, we estimate that the fraction of quasars in our sample hosting an intrinsic NAL system is 33 per cent. Lastly, we compare the properties of the material along the quasar line of sight, derived from our sample, with results based on close quasar pairs investigating the transverse direction. We find a deficiency of cool gas (traced by C II) along the line of sight connected to the quasar host galaxy, in contrast with what is observed in the transverse direction.
On the absorption of X-ray bright broad absorption line quasars
Arxiv preprint arXiv:0809.0832, 2008
Abstract: Most X-ray studies of BALQSOs found significant (N_H~ 10^{22-24} cm^{-2}) intrinsic column densities of gas absorbing an underlying typical power-law continuum emission, in agreement with expectations from radiatively driven accretion disk wind ...
High velocity outflows in narrow absorption line quasars
The current paradigm for the AGN phenomenon is a central engine that consists of an inflow of material accreting in the form of a disk onto a supermassive black hole. Observations in the UV and optical find high velocity ionized material outflowing from the black hole. We present results from Suzaku and XMM-Newton observations of a sample of intrinsic NAL quasars with high velocity outflows. Our derived values of the intrinsic column densities of the X-ray absorbers are consistent with an outflow scenario in which NAL quasars are viewed at smaller inclination angles than BAL quasars. We find that the distributions of alpha_ox and D(alpha_ox) of the NAL quasars of our sample differ significantly from those of BAL quasars and SDSS radio-quiet quasars. The NAL quasars are not significantly absorbed in the X-ray band and the positive values of D(alpha_ox) suggest absorption in the UV band. The positive values of D(alpha_ox) of the intrinsic NAL quasars can be explained in a geometric scenario where our lines of sight towards the compact X-ray hot coronae of NAL quasars do not traverse the absorbing wind whereas lines of sight towards their UV emitting accretion disks do intercept the outflowing absorbers.
AChandraSurvey of Broad Absorption Line Quasars
The Astrophysical Journal, 2001
We have carried out a survey with the Chandra X-Ray Observatory of a sample of 10 bright broad absorption line (BAL) quasars (QSOs). Eight of 10 sources are detected. The six brightest sources have only high-ionization BALs (hiBALs), while the four faintest all show low-ionization BALs (loBALs). We perform a combined spectral Ðt for hiBAL QSOs (384 counts total ; 0.5È6 keV) to determine the mean spectral parameters of this sample. We derive an underlying best-Ðt power-law slope ! \ 1.8^0.35, which is consistent with the mean slope for radio-quiet QSOs from ASCA, but BAL QSOs require a (rest-frame) absorbing column of cm~2, with a partial covering fraction of The 6.5~3 .8 4.5 ] 1022 D80~1 7 9 %. opticalÈtoÈX-ray spectral slope from 2500 to 2 keV) varies from 1.7 to 2.4 across the full sample, (a ox Ó consistent with previous results that BAL QSOs appear to be weak soft X-ray emitters. Removing the absorption component from our best-Ðt spectral model yields a range of from 1.55 to 2.28. All six a ox hiBAL QSOs have deabsorbed X-ray emission consistent with non-BAL QSOs of similar luminosity. The spectral energy distributions of the hiBAL QSOsÈboth the underlying power-law slope and the Ðrst conclusive evidence that BAL QSOs have appeared to be X-ray weak because of a ox Èprovide intrinsic absorption and that their underlying emission is consistent with non-BAL QSOs. By contrast, the removal of the best-Ðt absorption column detected in the hiBAL QSOs still leaves the four loBAL QSOs with values of that are unusually X-ray faint for their optical luminosities, which is consis-a ox [ 2 tent with other evidence that loBALs have higher column density, dustier absorbers. Important questions of whether BAL QSOs represent a special line of sight toward a QSO nucleus or rather an early evolutionary or high-accretion phase in a QSO lifetime remain to be resolved, and the unique properties of loBAL QSOs will be an integral part of that investigation.
A Census of Intrinsic Narrow Absorption Lines in the Spectra of Quasars at z = 2–4
The Astrophysical Journal Supplement Series, 2007
We use Keck/HIRES spectra of 37 optically bright quasars at z = 2-4 to study narrow absorption lines that are intrinsic to the quasars (intrinsic NALs, produced in gas that is physically associated with the quasar central engine). We identify 150 NAL systems, that contain 124 C IV, 12 N V, and 50 Si IV doublets, of which 18 are associated systems (within 5,000 km s −1 of the quasar redshift). We use partial coverage analysis to separate intrinsic NALs from NALs produced in cosmologically intervening structures. We find 39 candidate intrinsic systems, (28 reliable determinations and 11 that are possibly intrinsic). We estimate that 10-17% of C IV systems at blueshifts of 5,000-70,000 km s −1 relative to quasars are intrinsic. At least 32% of quasars contain one or more intrinsic C IV NALs. Considering N V and Si IV doublets showing partial coverage as well, at least 50% of quasars host intrinsic NALs. This result constrains the solid angle subtended by the absorbers to the background source(s). We identify two families of intrinsic NAL systems, those with strong N V absorption, and those with negligible absorption in N V, but with partial coverage in the C IV doublet. We discuss the idea that these two families represent different regions or conditions in accretion disk winds. Of the 26 intrinsic C IV NAL systems, 13 have detectable low-ionization absorption lines at similar velocities, suggesting that these are two-phase structures in the wind rather than absorbers in the host galaxy. We also compare possible models for quasar outflows, including radiatively accelerated disk-driven winds, magnetocentrifugally accelerated winds, and pressure-driven winds, and we discuss ways of distinguishing between these models observationally.
The X-ray emission from broad absorption line quasars
1999
PG 1411+442, and PG 0043+039. All three objects are found to be X-ray quiet, possibly due to substantial intrinsic absorption with N-H > 10(23) cm(-2) but might have intrinsically a more typical spectral energy distribution. This picture is supported by explicit spectral fits to the combined ROSAT/ASCA data of the nearby bright object PG 1411+442. An analysis of the large number of radio-quiet quasars not detected in the ROSAT All-Sky Survey indicates that perhaps only a small fraction of BAL quasars have not been recognized before and that the number of intrinsically X-ray quiet quasars must be small.