Physical Conditions in Quasar Outflows: VLT Observations of QSO 2359-1241 (original) (raw)
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Physical conditions in quasar outflows: very large telescope observations of QSO 2359-1241
The Astrophysical …, 2008
We analyze the physical conditions of the outflow seen in QSO 2359-1241 (NVSS J235953-124148), based on high resolution spectroscopic VLT observations. This object was previously studied using Keck/HIRES data. The main improvement over the HIRES results is our ability to accurately determine the number density of the outflow. For the major absorption component, level population from five different Fe II excited level yields n H = 10 4.4 cm −3 with less than 20% scatter. We find that the Fe II absorption arises from a region with 1 Based on observations made with ESO Telescopes at the Paranal Observatories under programme ID 078.B-0433(A) -2roughly constant conditions and temperature greater than 9000 K, before the ionization front where temperature and electron density drop. Further, we model the observed spectra and investigate the effects of varying gas metalicities and the spectral energy distribution of the incident ionizing radiation field. The accurately measured column densities allow us to determine the ionization parameter (log U H ≈ −2.4) and total column density of the outflow (log N H (cm −2 ) ≈ 20.6). Combined with the number density finding, these are stepping stones towards determining the mass flux and kinetic luminosity of the outflow, and therefore its importance to AGN feedback processes.
Physical Conditions in Quasar Outflows: VLT Observations of Qso 2359–1241 1
We analyze the physical conditions of the outflow seen in QSO 2359–1241 (NVSS J235953-124148), based on high resolution spectroscopic VLT observations. This object was previously studied using Keck/HIRES data. The main improvement over the HIRES results is our ability to accurately determine the number density of the outflow. For the major absorption component, level population from five different Fe II excited level yields nH = 104.4 cm−3 with less than 20 % scatter. We find that the Fe II absorption arises from a region with 1 Based on observations made with ESO Telescopes at the Paranal Observatories under programme ID
The Quasar Outflow Contribution to AGN Feedback: VLT Measurements of SDSS J0318-0600
The Astrophysical …, 2010
We present high spectral resolution VLT observations of the BAL quasar SDSS J0318-0600. This high quality data set allows us to extract accurate ionic column densities and determine an electron number density of n e =10 3.3±0.2 cm −3 for the main outflow absorption component. The heavily reddened spectrum of SDSS J0318-0600 requires purely silicate dust with a reddening curve characteristic of predominately large grains, from which we estimate the bolometric luminosity. We carry out photoionization modeling to determine the total column density, ionization parameter and distance of the gas and find that the photionization models suggest abundances greater than solar. Due to the uncertainty in the location of the dust extinction, we arrive at two viable distances for the main ouflow component from the central source, 6 and 18 kpc, where we consider the 6 kpc location as somewhat more physically plausable. Assuming the canonical global covering of 20% for the outflow and a distance of 6 kpc, our analysis yields a mass flux of 120 M ⊙ yr −1 and a kinetic luminosity that is ∼0.1% of the bolometric luminosity of the object. Should the dust be part of the outflow, then these values are ∼4× larger. The large mass flux and kinetic luminosity make this outflow a significant contributor to AGN feedback processes.
Using high-resolution Very Large Telescope spectra, we study the multi-component outflow systems of two quasars exhibiting intrinsic Fe ii absorption (QSO 2359-1241 and SDSS J0318-0600). From the extracted ionic column densities and using photoionization modeling, we determine the gas density, total column density, and ionization parameter for several of the components. For each object, the largest column density component is also the densest, and all other components have densities of roughly 1/4 of that of the main component. We demonstrate that all the absorbers lie roughly at the same distance from the source. Further, we calculate the total kinetic luminosities and mass outflow rates of all components and show that these quantities are dominated by the main absorption component.
Quasar Outflow Contribution to AGN Feedback: Observations of QSO SDSS J0838+ 2955
We present a detailed analysis of the Astrophysical Research Consortium 3.5m telescope spectrum of QSO SDSS J0838+2955. The object shows three broad absorption line (BAL) systems at 22,000, 13,000, and 4900 km s −1 blueshifted from the systemic redshift of z=2.043. Of particular interest is the lowest velocity system that displays absorption from low-ionization species such as Mg ii, Al ii, Si ii, Si ii*, Fe ii and Fe ii*. Accurate column densities were measured for all transitions in this lowest velocity BAL using an inhomogeneous absorber model. The ratio of column densities of Si ii* and Fe ii* with respect to their ground states gave an electron number density of log n e (cm −3 ) = 3.75 ± 0.22 for the outflow. Photoionization modeling with careful regards to chemical abundances and the incident spectral energy distribution predicts an ionization parameter of log U H = -1.93 ± 0.21 and a hydrogen column density of log N H (cm −2 ) = 20.80 ± 0.28. This places the outflow at 3.3 +1.5 −1.0 kpc from the central active galactic nucleus (AGN). Assuming that the fraction of solid angle subtended by the outflow is 0.2, these values yield a kinetic luminosity of (4.5 +3.1 −1.8 ) × 10 45 erg s −1 , which is (1.4 +1.1 −0.6 )% the bolometric luminosity of the QSO itself. Such large kinetic luminosity suggests that QSO outflows are a major contributor to AGN feedback mechanisms.
Metal-Enriched Outflows in the Ultraluminous Infrared Quasar Q1321+058
Quasar outflows may play important role in the evolution of its host galaxy and central black hole, and are most often studied in absorption lines. In this paper, we present a detailed study of multiple outflows in the obscured ultraluminous infrared quasar Q1321+058. The outflows reveal themselves in the complex optical and ultraviolet (UV) emission-line spectrum, with a broad component blueshifted by 1650 km s −1 and a narrow component by 360 km s −1 , respectively. The higher velocity component shows ever strong N iii] (N iii]/C iii] = 3.8 ± 0.3 and N iii]/C iv = 0.53) and strong Si iii] (Si iii]/C iii] 1), in addition to strong [O iii]λ5007 and [Ne iii]λ3869 emission. A comparison of these line ratios with photoionization models suggests an overabundance of N and Si relative to C. The abundance pattern is consistent with a fast chemical enriching process associated with a recent starburst, triggered by a recent galaxy merger. The outflow extends to several tens to hundred parsecs from the quasar, and covers only a very small sky. We find that the outflow with line emitting gas is energetically insufficient to remove the interstellar medium of the host galaxy, but total kinetic energy may be much larger than suggested by the emission lines. The velocity range and the column density suggest that the outflow might be part of the low-ionization broad absorption line region as seen in a small class of quasars. The optical and UV continuum is starlight dominated and can be modeled with a young-aged (1 Myr) plus an intermediate-aged (∼0.5-1 Gyr) stellar populations, suggesting a fast building of the stellar mass in the host galaxy, consistent with the starburst-type metal abundances inferred from the high-velocity outflow spectrum.
The extremely high velocity outflow in quasar PG0935+417
Monthly Notices of the Royal Astronomical Society, 2010
We report the detection of O VI λλ1031, 1037 and N V λλ1238, 1242 absorption in a system of 'mini-broad' absorption lines (mini-BALs) previously reported to have variable C IV λλ1548, 1550 in the quasar PG0935+417. The formation of these lines in an extremely high velocity outflow (with v ∼ −50 000 km s −1) is confirmed by the line variability, broad smooth absorption profiles and partial covering of the background light source. H I and lower-ionization metals are not clearly present. The line profiles are complex and asymmetric, with full widths at half-minimum (FWHM) of different components in the range ∼660 to ∼2510 km s −1. The resolved O VI doublet indicates that these lines are moderately saturated, with the absorber covering ∼80 per cent of the quasar continuum source (C f ∼ 0.8). We derive ionic column densities of the order of 10 15 cm −2 in C IV and several times larger in O VI, indicating an ionization parameter of log U −0.5. Assuming solar abundances, we estimate a total column density of N H ∼ 5 × 10 19 cm −2. Comparisons to data in the literature show that this outflow emerged sometime between 1982 when it was clearly not present and 1993 when it was first detected. Our examination of the C IV data from 1993 to 2007 shows that there is variable complex absorption across a range of velocities from −45 000 to −54 000 km s −1. There is no clear evidence for acceleration or deceleration of the outflow gas. The observed line variations are consistent with either changes in the ionization state of the gas or clouds crossing our lines of sight to the continuum source. In the former case, the recombination times constrain the location of outflow to be at a radial distance of r 1.2 kpc with density of n H 1.1 × 10 4 cm −3. In the latter case, the nominal transit times of moving clouds indicate r 0.9 pc. Outflows are common in active galactic nuclei (AGN), but extreme speeds such as those reported here are extremely rare. It is not clear what properties of PG 0935+417 might produce this unusual outflow. The quasar is exceptionally luminous, with L ∼ 6 × 10 47 erg s −1 , but it has just a modest Eddington ratio, L/L Edd ∼ 0.2, and no apparent unusual properties compared to other quasars. In fact, PG 0935+417 has significantly less X-ray absorption than typical BAL quasars even though its outflow has a degree of ionization typical of BALs at speeds that are 2-3 times larger than most BALs. These results present a challenge to theoretical models that invoke strong radiative shielding in the X-rays/far-UV to moderate the outflow ionization and thus enable its radiative acceleration to high speeds.
The Astrophysical …, 2010
Using high-resolution Very Large Telescope spectra, we study the multi-component outflow systems of two quasars exhibiting intrinsic Fe ii absorption (QSO 2359-1241 and SDSS J0318-0600). From the extracted ionic column densities and using photoionization modeling, we determine the gas density, total column density, and ionization parameter for several of the components. For each object, the largest column density component is also the densest, and all other components have densities of roughly 1/4 of that of the main component. We demonstrate that all the absorbers lie roughly at the same distance from the source. Further, we calculate the total kinetic luminosities and mass outflow rates of all components and show that these quantities are dominated by the main absorption component.
The Astrophysical …, 2011
We present absorption line analysis of the outflow in the quasar IRAS F04250-5718. Far-ultraviolet data from the Cosmic Origins Spectrograph onboard the Hubble Space Telescope reveal intrinsic narrow absorption lines from high ionization ions (e.g., C iv, N v, and O vi) as well as low ionization ions (e.g., C ii and Si iii). We identify three kinematic components with central velocities ranging from ∼ -50 to ∼ -230 km s −1 . Velocity dependent, non-black saturation is evident from the line profiles of the high ionization ions. From the non-detection of absorption from a metastable level of C ii, we are able to determine that the electron number density in the main component of the outflow is < ∼ 30 cm −3 . Photoionization analysis yields an ionization parameter log U H ∼ −1.6 ± 0.2, which accounts for changes in the metallicity of the outflow and the shape of the incident spectrum. We also consider solutions with two ionization parameters. If the ionization structure of the outflow is due to photoionization by the active galactic nucleus, we determine that the distance to this component from the central source is > ∼ 3 kpc. Due to the large distance determined for the main kinematic component, we discuss the possibility that this outflow is part of a galactic wind.
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.