Search

We present the Data Release 12 Quasar catalog (DR12Q) from the Baryon Oscillation Spectroscopic Survey (BOSS) of the Sloan Digital Sky Survey III. This catalog includes all SDSS-III/BOSS objects that were spectroscopically targeted as quasar candidates during the full survey and that are confirmed as quasars via visual inspection of the spectra, have luminosities Mi [z = 2] 2.15 (184 101, of which 167 742 are new discoveries) is about an order of magnitude greater than the number of z > 2.15 quasars known prior to BOSS. Redshifts and FWHMs are provided for the strongest emission lines (C iv, C iii], Mg ii). The catalog identifies 29 580 broad absorption line quasars and lists their characteristics. For each object, the catalog presents five-band (u, g, r, i, z) CCD-based photometry with typical accuracy of 0.03 mag together with some information on the optical morphology and the selection criteria. When available, the catalog also provides information on the optical variability of quasars using SDSS and Palomar Transient Factory multi-epoch photometry. The catalog also contains X-ray, ultraviolet, near-infrared, and radio emission properties of the quasars, when available, from other large-area surveys. The calibrated digital spectra, covering the wavelength region 3600-10 500 Å at a spectral resolution in the range 1300 < R < 2500, can be retrieved from the SDSS Catalog Archive Server. We also provide a supplemental list of an additional 4841 quasars that have been identified serendipitously outside of the superset defined to derive the main quasar catalog.

We present the Data Release 10 Quasar (DR10Q) catalog from the Baryon Oscillation Spectroscopic Survey (BOSS) of the Sloan Digital Sky Survey III. The catalog includes all BOSS objects that were targeted as quasar candidates during the first 2.5 years of the survey and that are confirmed as quasars via visual inspection of the spectra, have luminosities Mi[z = 2] 2.15 (117 668) is ~5 times greater than the number of z > 2.15 quasars known prior to BOSS. Redshifts and FWHMs are provided for the strongest emission lines (C iv, C iii, Mg ii). The catalog identifies 16 461 broad absorption line quasars and gives their characteristics. For each object, the catalog presents five-band (u, g, r, i, z) CCD-based photometry with typical accuracy of 0.03 mag and information on the optical morphology and selection method. The catalog also contains X-ray, ultraviolet, near-infrared, and radio emission properties of the quasars, when available, from other large-area surveys. The calibrated digital spectra cover the wavelength region 3600-10 500 Å at a spectral resolution in the range 1300 < R < 2500; the spectra can be retrieved from the SDSS Catalog Archive Server. We also provide a supplemental list of an additional 2376 quasars that have been identified among the galaxy targets of the SDSS-III/BOSS. © 2014 ESO.

We study the connection between the X-ray and ultraviolet (UV) properties of the broad absorption line (BAL) wind in the highly X-ray variable quasar PG 2112+059 by comparing Chandra -ACIS data with contemporaneous UV HST /STIS spectra in three different epochs. We observe a correlation whereby an increase in the equivalent widths (EWs) of the BALs is accompanied by a redder UV spectrum. The growth in the BAL EWs is also accompanied by a significant dimming in soft X-ray emission (⁠|${\lesssim}2 \, \text{keV}$|⁠), consistent with increased absorption. Variations in the hard X-ray emission (⁠|${\gtrsim}2\, \text{keV}$|⁠) are only accompanied by minor spectral variations of the UV-BALs and do not show significant changes in the EW of BALs. These trends suggest a wind-shield scenario where the outflow inclination with respect to the line of sight is decreasing and/or the wind mass is increasing. These changes elevate the covering fraction and/or column densities of the BALs and are likely accompanied by a nearly contemporaneous increase in the column density of the shield. [ABSTRACT FROM AUTHOR]

We present a dynamical study of the narrow-line regions in two nearby type 2 quasars (QSO2s). We construct dynamical models based on detailed photoionization models of the emission-line gas, including the effects of internal dust, to apply to observations of large-scale outflows from these active galactic nuclei (AGNs). We use Mrk 477 and Mrk 34 in order to test our models against recent Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS) observations of [O  iii ] emission-line kinematics, since these AGNs possess more energetic outflows than found in Seyfert galaxies. We find that the outflows within 500 pc are consistent with radiative acceleration of dusty gas, however the outflows in Mrk 34 are significantly more extended and may not be directly accelerated by radiation. We characterize the properties of X-ray winds found from the expansion of [O  iii ]-emitting gas close to the black hole. We show that such winds possess the kinetic energy density to disturb [O  iii ] gas at ∼1.8 kpc, and have sufficient energy to entrain the [O  iii ] clouds at ∼1.2 kpc. Assuming that the X-ray wind possesses the same radial mass distribution as the [O  iii ] gas, we find that the peak kinetic luminosity for this wind is 2 per cent of Mrk 34's bolometric luminosity, which is in the 0.5–5 per cent range required by some models for efficient feedback. Our work shows that, although the kinetic luminosity as measured from [O  iii ]-emitting gas is frequently low, X-ray winds may provide more than one order of magnitude higher kinetic power. [ABSTRACT FROM AUTHOR]

Abiotic stresses strongly impair plant development and might impose detrimental effects particularly on seedlings. Irradiance and water deficit are relevant factors, which affect performance of young plants under controlled conditions. In our study, we investigated the influence of water shortage combined with different radiation sources - light emitting diodes (LED) and compact fluorescence lamps (CFL) - on physiological and biochemical parameters of young apple plants. Stress responses were assessed by fluorescence-based indices, while relative water, chlorophyll (Chl), and proline content served as reference parameters. The watering regime had a higher impact on biochemical indicators than the radiation sources. Lower Chl content was determined in plants grown under LED both in control and in water deficit plants. Nitrogen balance index and nitrogen balance index with red radiation excitation showed similar patterns regarding leaf Chl results in relation to the radiation source, being higher under CFL. In contrast, the flavonol index was higher in plants cultivated under LED. Stomatal conductance and maximal photochemical efficiency emphasised a radiation quality effect with higher values for CFL. In conclusion, fluorescence indices related to nitrogen status and flavonol content are promising parameters to sense physiological impairments under the given conditions. However, discrepancies compared to previous studies might be related to the different plant species, the nature of dehydration, and the measuring conditions. [ABSTRACT FROM AUTHOR]

We use Hubble Space Telescope /Space Telescope Imaging Spectrograph long-slit G430M and G750M spectra to analyse the extended [O  iii ] λ5007 emission in a sample of 12 nearby (z < 0.12) luminous (L bol > 1.6 × 1045 erg s−1) QSO2s. The purpose of the study is to determine the properties of the mass outflows of ionized gas and their role in active galactic nucleus feedback. We measure fluxes and velocities as functions of radial distances. Using cloudy models and ionizing luminosities derived from [O  iii ] λ5007, we are able to estimate the densities for the emission-line gas. From these results, we derive masses of [O  iii ]-emitting gas, mass outflow rates, kinetic energies, kinetic luminosities, momenta, and momentum flow rates as a function of radial distance for each of the targets. For the sample, masses are several times |$10^{3}$| – |$10^{7}\, {\rm M_{\odot }}$| and peak outflow rates are from 9.3 × 10−3 to |$10.3\, {\rm M_{\odot }}\, {\rm yr^{-1}}$|⁠. The peak kinetic luminosities are (3.4 × 10−8)–(4.9 × 10−4) of the bolometric luminosity, which does not approach the (5.0 × 10−3)–(5.0 × 10−2) range required by some models for efficient feedback. For Mrk 34, which has the largest kinetic luminosity of our sample, in order to produce efficient feedback there would have to be 10 times more [O  iii ]-emitting gas than that we detected at its position of maximum kinetic luminosity. Three targets show extended [O  iii ] emission, but compact outflow regions. This may be due to different mass profiles or different evolutionary histories. [ABSTRACT FROM AUTHOR]

Past X-ray observations of the nearby luminous quasar PDS 456 (at z = 0.184) have revealed a wide-angle accretion disk wind with an outflow velocity of ∼−0.25c, as observed through observations of its blueshifted iron K-shell absorption line profile. Here we present three new XMM-Newton observations of PDS 456: one in 2018 September where the quasar was bright and featureless and two in 2019 September, 22 days apart, occurring when the quasar was five times fainter and where strong blueshifted lines from the wind were present. During the second 2019 September observation, three broad (σ = 3000 km s−1) absorption lines were resolved in the high-resolution Reflection Grating Spectrometer spectrum that are identified with blueshifted O viii Lyα, Ne ix Heα, and Ne x Lyα. The outflow velocity of this soft X-ray absorber was found to be v/c = −0.258 ± 0.003, fully consistent with an iron K absorber with v/c = −0.261 ± 0.007. The ionization parameter and column density of the soft X-ray component (log ξ = 3.4, NH = 2 × 1021 cm−2) outflow was lower by about 2 orders of magnitude when compared to the high-ionization wind at iron K (log ξ = 5, NH = 7 × 1023 cm−2). Substantial variability was seen in the soft X-ray absorber between the 2019 observations, declining from NH = 1023 to 1021 cm−2 over 20 days, while the iron K component was remarkably stable. We conclude that the soft X-ray wind may originate from an inhomogeneous wind streamline passing across the line of sight that, due to its lower ionization, is located further from the black hole, on parsec scales, than the innermost disk wind. [ABSTRACT FROM AUTHOR]

We investigate extremely red quasars (ERQs), a remarkable population of heavily reddened quasars at redshift z  ∼ 2−3 that might be caught during a short-lived 'blow-out' phase of quasar/galaxy evolution. We perform a near-IR observational campaign using Keck/NIRSPEC, VLT/X-shooter, and Gemini/GNIRS to measure rest-frame optical spectra of 28 ERQs with median infrared luminosity 〈log L (erg s−1)〉 ∼ 46.2. They exhibit the broadest and most blueshifted [O  iii ] λ4959,5007 emission lines ever reported, with widths (w 90) ranging between 2053 and 7227 km s−1, and maximum outflow speeds (v98) up to 6702 km s−1. ERQs on average have [O  iii ] outflows velocities about three times larger than those of luminosity-matched blue quasar samples. This discrepancy can be explained by a strong correlation between [O  iii ] kinematics and i–W3 colour, and not by radio loudness, or higher Eddington ratios. We estimate for these objects that at least 3–5 per cent of their bolometric luminosity is being converted into the kinetic power of the observed wind. Our results reveal that ERQs have the potential to strongly affect the evolution of host galaxies. [ABSTRACT FROM AUTHOR]

Theoretical models have suggested an evolutionary model for quasars, in which most of luminous quasars are triggered by major mergers. It is also postulated that reddening as well as powerful outflows indicate an early phase of activity, close to the merger event. We test this model on a sample of quasars with powerful low-ionization outflows seen in broad iron absorption lines (FeLoBAL). This sample of objects show strong reddening in the optical and fast (∼0.1c) high-column density outflows. We present HST WFC3/IR F160W imaging of 10 FeLoBAL host galaxies at redshifts |$z$| ∼ 0.9 (⁠|$\lambda _{\mathrm{ rest}}\sim 8500\, \mathrm{\mathring{\rm A} }$|⁠). We compare the host galaxy morphologies and merger signatures of FeLoBALs to luminous blue non-BAL quasars from Villforth et al. (2017) of comparable luminosity, which show no excess of merger features compared to inactive control samples. If FeLoBAL quasars are indeed in a young evolutionary state, close in time to the initial merging event, they should have strong merger features. We find that the host galaxies of FeLoBAL quasars are of comparable luminosity to the host galaxies of optical quasars and show no enhanced merger rates. When looking only at quasars without strong point spread function residuals, an enhancement in disturbed and merger rates is seen. While FeLoBAL hosts show weak enhancements over a control of blue quasars, their host galaxies are not dominated by recent major mergers. [ABSTRACT FROM AUTHOR]

We investigate the N  v absorption signal along the line of sight of background quasars, in order to test the robustness of the use of this ion as the criterion to select intrinsic (i.e. physically related to the quasar host galaxy) narrow absorption lines (NALs). We build composite spectra from a sample of ∼ 1000 C  iv absorbers, covering the redshift range 2.55 < z < 4.73, identified in 100 individual sight lines from the XQ-100 Legacy Survey. We detect a statistically significant N  v absorption signal only within 5000 km s−1 of the systemic redshift, |$z_{\rm em}$|⁠. This absorption trough is ∼ 15 σ when only C  iv systems with N (C  iv) > 1014 cm−2 are included in the composite spectrum. This result confirms that N  v offers an excellent statistical tool to identify intrinsic systems. We exploit stacks of 11 different ions to show that the gas in proximity to a quasar exhibits a considerably different ionization state with respect to gas in the transverse direction and intervening gas at large velocity separations from the continuum source. Indeed, we find a dearth of cool gas, as traced by low-ionization species and in particular by Mg  ii, in the proximity of the quasar. We compare our findings with the predictions given by a range of cloudy ionization models and find that they can be naturally explained by ionization effects of the quasar. [ABSTRACT FROM AUTHOR]

Quasar outflows have long been recognized as potential contributors to the co-evolution between supermassive black holes (SMBHs) and their host galaxies. The role of outflows in active galactic nucleus (AGN) feedback processes can be better understood by placing observational constraints on wind locations and kinetic energies. We utilize broad absorption line (BAL) variability to investigate the properties of a sample of 71BAL quasarswith P V broad absorption. The presence of P V BALs indicates that other BALs like C IV are saturated, such that variability in those lines favours clouds crossing the line of sight.We use these constraints with measurements of BALvariability to estimate outflowlocations and energetics. Our data set consists of multiple-epoch spectra from the Sloan Digital Sky Survey and MDM Observatory. We detect significant (4σ) BAL variations from 10 quasars in our sample over rest-frame timescales between ≤0.2-3.8 yr. Our derived distances for the 10 variable outflows are nominally ≲1-10 pc from the SMBH using the transverse-motion scenario, and ≲100-1000 pc from the central source using ionization-change considerations. These distances, in combination with the estimated high outflow column densities (i.e. NH ≳ 1022 cm-2), yield outflow kinetic luminosities between ~0.001 and 1 times the bolometric luminosity of the quasar, indicating that many absorber energies within our sample are viable for AGN feedback. [ABSTRACT FROM AUTHOR]

Broad absorption lines (BALs) found in a significant fraction of quasar spectra identify highvelocity outflows that might be present in all quasars and could be a major factor in feedback to galaxy evolution. Understanding the nature of these flows requires further constraints on their physical properties, including their column densities, for which well-studied BALs, such as CIV λλ1548,1551, typically provide only a lower limit because of saturation effects. Low abundance lines, such as P V λλ1118,1128, indicate large column densities, implying that outflows more powerful than measurements of C IV alone would indicate. We search through a sample of 2694 BAL quasars from the Sloan Digital Sky Survey III/Baryon Oscillation Spectroscopic Survey data release 9 quasar catalogue for such absorption, and we identify 81 ‘definite’ and 86 ‘probable’ detections of P V broad absorption, yielding a firm lower limit of 3.0–6.2 per cent for the incidence of such absorption among BAL quasars. The P V-detected quasars tend to have stronger C IV and Si IV absorption, as well as a higher incidence of LoBAL absorption, than the overall BAL quasar population. Many of the P V-detected quasars have C IV troughs that do not reach zero intensity (at velocities where P V is detected), confirming that the outflow gas only partially covers the UV continuum source. P V appears significantly in a composite spectrum of non-P V-detected BAL quasars, indicating that P V absorption (and large column densities) is much more common than indicated by our search results. Our sample of P V detections significantly increases the number of known P V detections, providing opportunities for follow-up studies to better understand BAL outflow energetics. [ABSTRACT FROM AUTHOR]

Quasar outflows have been posited as a mechanism to couple supermassive black holes to evolution in their host galaxies.We use multi-epoch spectra from the Hubble Space Telescope (HST) and ground-based observatories to study the outflows in seven quasars that have CIV outflow lines ranging from a classic broad absorption line (BAL) to weaker/narrower 'mini-BALs' across restwavelengths of at least 850-1650 Å. The CIV outflowlines all variedwithin a time frame of ≤1.9 yr (rest). This includes equal occurrences of strengthening and weakening plus the emergence of a new BAL system at -38 800 km s-1 accompanied by dramatic strengthening in a mini-BAL at -22 800 km s-1. We infer from ∼1:1 doublet ratios in P V and other lines that the BAL system is highly saturated with line-of-sight covering fractions ranging from 0.27 to 0.80 in the highest to lowest column density regions, respectively. Three of the mini-BALs also provide evidence for saturation and partial covering based on ∼1:1 doublet ratios.We speculate that the BALs and mini-BALs form in similar clumpy/filamentary outflows, with mini-BALs identifying smaller or fewer clumps along our lines of sight. If we attribute the line variabilities to clumps crossing our lines of sight at roughly Keplerian speeds, then a typical variability time in our study, ∼1.1 yr, corresponds to a distance ∼2 pc from the central black hole. Combining this with the speed and minimum total column density inferred from the P V BAL, NH ≳ 2.5 × 1022 cm-2, suggests that the BAL outflow kinetic energy is in the range believed to be sufficient for feedback to galaxy evolution. [ABSTRACT FROM AUTHOR]

We statistically study the physical properties of a sample of narrow absorption line (NAL) systems looking for empirical evidences to distinguish between intrinsic and interveningNALs without taking into account any a priori definition or velocity cut-off. We analyse the spectra of 100 quasars with 3.5 < zem < 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 < 0.2Å) are also considered. We infer NV 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. [ABSTRACT FROM AUTHOR]

The physical scenario describing the origin of quasar winds remains largely unsettled due to our failure to account for X-ray weak BAL quasars. We approach this problem by studying the relation between the inner part of the outflow which is likely to be shielding the X-ray emission and the UV winds characterized by broad absorption lines (BALs). In particular, we aim to probe the wind-shield connection in the highly X-ray variable BAL quasar PG 2112+059, which has exhibited periods of X-ray weakness and X-ray normality in the past. A set of two 20 ks Chandra observations and two contemporaneous HST observations, separated by at least eight months, combined with a nearly simultaneous archival Chandra -HST observation from 2002, afford us a unique opportunity to study the connection between the shield (which is thought to be responsible for the X-ray absorption) and the ionization state of the wind (observed as UV BAL features; e.g., Civ and Ovi lines) over various timescales. In this review, which was based on a presentation in the XMM-Newton 2015 Science Workshop, we provide background relevant to our study and briefly analyze a recent Chandra observation of our new set of multiwavelength observations of PG 2112+059. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Iron low-ionization broad absorption lines (FeLoBALs) trace a rare class of quasar outflows with large column densities and potentially large kinetic energies that might be important for 'feedback' to galaxy evolution. In order to probe the physical properties of these outflows, we conducted a multiple-epoch, absorption line variability study of 12 FeLoBAL quasars spanning a redshift range of 0.7 ≤ z ≤ 1.9 over rest-frame time-scales of ∼10 d to 7.6 yr. We detect absorption line variability with ≥8σ confidence in 3 out of the 12 sources in our sample over time-scales of ∼0.6 to 7.6 yr. Variable wavelength intervals are associated with ground- and excited-state Fe II multiplets, the Mg II λλ2796, 2803 doublet, Mg I λ2852, and excited-state Ni II multiplets. The observed variability along with evidence of saturation in the absorption lines favours transverse motions of gas across the line of sight as the preferred scenario, and allows us to constrain the outflow distance from the supermassive black hole to be ≲69, 7, and 60 pc for our three variable sources. In combination with other studies, these results suggest that the outflowing gas in FeLoBAL quasars resides on a range of scales and includes matter within tens of parsecs of the central source. [ABSTRACT FROM AUTHOR]

The one-dimensional magnetohydrodynamics of a plasma cylindrical liner is addressed in the case of a two components magnetic field. The azimuthal component is responsible for the implosion of the liner and the axial field is compressed inside the liner. A complete set of analytical profiles for the magnetic field components, the density, and the local velocity are proposed at the scale of the liner thickness. Numerical simulations are also presented to test the validity of the analytical formulas. [ABSTRACT FROM AUTHOR]

Broad absorption lines (BALs) in quasar spectra identify high-velocity outflows that might exist in all quasars and could play a major role in feedback to galaxy evolution. The viability of BAL outflows as a feedback mechanism depends on their kinetic energies, as derived from the outflow velocities, column densities, and distances from the central quasar. We estimate these quantities for the quasar, Q1413+1143 (redshift ze = 2.56), aided by the first detection of P v λλ1118, 1128 BAL variability in a quasar. In particular, P v absorption at velocities where the C iv trough does not reach zero intensity implies that the C iv BAL is saturated and the absorber only partially covers the background continuum source (with characteristic size <0.01 pc). With the assumption of solar abundances, we estimate that the total column density in the BAL outflow is log NH ≳ 22.3 cm−2. Variability in the P v and saturated C iv BALs strongly disfavours changes in the ionization as the cause of the BAL variability, but supports models with high column density BAL clouds moving across our lines of sight. The observed variability time of 1.6 yr in the quasar rest frame indicates crossing speeds >750 km s−1 and a radial distance from the central black hole of ≲ 3.5 pc, if the crossing speeds are Keplerian. The total outflow mass is ∼4100 M⊙, the kinetic energy ∼4 × 1054 erg, and the ratio of the outflow kinetic energy luminosity to the quasar bolometric luminosity is ∼0.02 (at the minimum column density and maximum distance), which might be sufficient for important feedback to the quasar's host galaxy. [ABSTRACT FROM PUBLISHER]

We present results from an observation of the gravitationally lensed z = 1.51 narrow absorption line (NAL) active galactic nucleus (AGN) HS 0810+2554 performed with the Chandra X-Ray Observatory. The factor of ∼100 lensing magnification of HS 0810+2554 makes this source exceptionally bright. Absorption lines are detected at rest-frame energies of ∼7.7 keV and ∼11.0 keV at ≳97% significance. By interpreting these lines to arise from highly ionized iron the implied outflow velocities of the X-ray absorbing gas corresponding to these lines are 0.13c and 0.41c, respectively. The presence of these relativistic outflows and the absence of any significant low-energy X-ray absorption suggest that a shielding gas is not required for the generation of the relativistic X-ray absorbing winds in HS 0810+2554. UV spectroscopic observations with VLT/UVES indicate that the UV absorbing material is outflowing at vUV ∼0.065c. Our analysis indicates that the fraction of the total bolometric energy released by HS 0810+2554 into the intergalactic medium (IGM) in the form of kinetic energy is εk = 1.0. An efficiency of greater than unity implies that magnetic driving is likely a significant contributor to the acceleration of this X-ray absorbing wind. We also estimate the mass-outflow rate of the strongest absorption component to be = 1.1 M☼ yr–1. Assuming that the energetic outflow detected in the NAL AGN HS 0810+2554 is a common property of most AGN it would suggest that the X-ray absorbing wind may have a larger opening angle than previously thought. This has important consequences for estimating the feedback contribution of X-ray absorbing winds to the surrounding IGM. [ABSTRACT FROM AUTHOR]

We present a detailed investigation of the variability of 428 C IV and 235 Si IV broad absorption line (BAL) troughs identified in multi-epoch observations of 291 quasars by the Sloan Digital Sky Survey-I/II/III. These observations primarily sample rest-frame timescales of 1-3.7 yr over which significant rearrangement of the BAL wind is expected. We derive a number of observational results on, e.g., the frequency of BAL variability, the velocity range over which BAL variability occurs, the primary observed form of BAL-trough variability, the dependence of BAL variability upon timescale, the frequency of BAL strengthening versus weakening, correlations between BAL variability and BAL-trough profiles, relations between C IV and Si IV BAL variability, coordinated multi-trough variability, and BAL variations as a function of quasar properties. We assess implications of these observational results for quasar winds. Our results support models where most BAL absorption is formed within an order-of-magnitude of the wind-launching radius, although a significant minority of BAL troughs may arise on larger scales. We estimate an average lifetime for a BAL trough along our line-of-sight of a few thousand years. BAL disappearance and emergence events appear to be extremes of general BAL variability, rather than being qualitatively distinct phenomena. We derive the parameters of a random-walk model for BAL EW variability, finding that this model can acceptably describe some key aspects of EW variability. The coordinated trough variability of BAL quasars with multiple troughs suggests that changes in “shielding gas” may play a significant role in driving general BAL variability. [ABSTRACT FROM AUTHOR]

Broad absorption lines (BALs) in quasar spectra are prominent signatures of high-velocity outflows, which might be present in all quasars and could be a major contributor to feedback to galaxy evolution. Studying the variability in these BALs allows us to further our understanding of the structure, evolution and basic physical properties of the outflows. This is the third paper in a series on a monitoring programme of 24 luminous BAL quasars at redshifts 1.2 < z < 2.9. We focus here on the time-scales of variability in C iv λ1549 BALs in our full multi-epoch sample, which covers time-scales from 0.02 to 8.7 yr in the quasar rest frame. Our sample contains up to 13 epochs of data per quasar, with an average of seven epochs per quasar. We find that both the incidence and the amplitude of variability are greater across longer time-scales. Part of our monitoring programme specifically targeted half of these BAL quasars at rest-frame time-scales ≤2 months. This revealed variability down to the shortest time-scales we probe (8–10 d). Observed variations in only portions of BAL troughs or in lines that are optically thick suggest that at least some of these changes are caused by clouds (or some type of outflow substructures) moving across our lines of sight. In this crossing cloud scenario, the variability times constrain both the crossing speeds and the absorber locations. Specific results also depend on the emission and absorption geometries. We consider a range of geometries and use Keplerian rotational speeds to derive a general relationship between the variability times, crossing speeds and outflow locations. Typical variability times of the order of ∼1 yr indicate crossing speeds of a few thousand km s−1 and radial distances ∼1 pc from the central black hole. However, the most rapid BAL changes occurring in 8–10 d require crossing speeds of 17 000–84 000 km s−1 and radial distances of only 0.001–0.02 pc. These speeds are similar to or greater than the observed radial outflow speeds, and the inferred locations are within the nominal radius of the broad emission-line region. [ABSTRACT FROM PUBLISHER]

ABSTRACT We present Herschel-PACS spectroscopy of the [O i]63 μm far-infrared cooling line from a sample of six unlensed and spectroscopically confirmed 870 μm selected submillimetre (submm) galaxies (SMGs) at 1.1 < z < 1.6 from the LABOCA Extended Chandra Deep Field South (ECDFS) Submm Survey (LESS). This is the first survey of [O i]63 μm, one of the main photodissociation region (PDR) cooling lines, in SMGs. New high-resolution Atacama Large Millimetre Array (ALMA) interferometric 870 μm continuum imaging confirms that these six Herschel-targeted SMG counterparts are bona fide sources of submm emission. We detect [O i]63 μm in two SMGs with an SNR ≳ 3, tentatively detect [O i]63 μm in one SMG and constrain the line flux for the non-detections. We also exploit the combination of submm continuum photometry from 250 to 870 μm and our new PACS continuum measurements to constrain the far-infrared luminosity, LFIR, in these SMGs to ≲30 per cent. We find that SMGs do not show a deficit in their [O i]63 μm-to-far-infrared (FIR) continuum luminosity ratios (with ratios ranging from ≃0.5 to 1.5 per cent), similar to what was seen previously for the [C ii]158 μm-to-FIR ratios in SMGs. These observed ratios are about an order of magnitude higher than what is seen typically for local ultraluminous infrared galaxies (ULIRGs), which adds to the growing body of evidence that SMGs are not simply 'scaled up' versions of local ULIRGs. Rather, the PDR line-to- LFIR ratios suggest that the star formation modes of SMGs are likely more akin to that of local normal (lower-luminosity) star-forming galaxies, with the bulk of the star formation occurring in extended galaxy-scale (∼kpc) regions. These observations represent the first step towards a census of the major PDR cooling lines in typical SMGs that will be attainable with ALMA, enabling detailed modelling to probe the global properties of the star formation and the evolutionary status of SMGs. [ABSTRACT FROM AUTHOR]

ABSTRACT Broad absorption lines (BALs) in quasar spectra indicate high-velocity outflows that may be present in all quasars and could be an important contributor to feedback to their host galaxies. Variability studies of BALs help illuminate the structure, evolution and basic physical properties of the outflows. Here we present further results from an ongoing BAL monitoring campaign of a sample of 24 luminous quasars at redshifts 1.2 < z < 2.9. We directly compare the variabilities in the C ivλ1549 and Si ivλ1400 absorption to try to ascertain the cause(s) of the variability. We find that Si iv BALs are more likely to vary than C iv BALs. When looking at flow speeds >−20 000 km s−1, 47 per cent of quasars exhibited Si iv variability while 31 per cent exhibited C iv variability. Furthermore, ∼50 per cent of the variable Si iv regions did not have corresponding C iv variability at the same velocities, while nearly all occurrences of C iv variability had corresponding changes in Si iv. We do not find any correlation between the absolute change in strength in C iv and in Si iv, but the fractional change in strength tends to be greater in Si iv than in C iv. When both C iv and Si iv varied, those changes always occurred in the same sense (either getting weaker or stronger). We also include our full data set so far in this paper, which includes up to 10 epochs of data per quasar. The multi-epoch data show that the BAL changes were not generally monotonic across the full ∼5-8 yr time span of our observations, suggesting that the characteristic time-scale for significant line variations, and (perhaps) for structural changes in the outflows, is less than a few years. Coordinated variabilities between absorption regions at different velocities in individual quasars seem to favour changing ionization of the outflowing gas as the cause of the observed BAL variability. However, variability in limited portions of broad troughs fits naturally in a scenario where movements of individual clouds, or substructures in the flow, across our lines of sight cause the absorption to vary. The actual situation may be a complex mixture of changing ionization and cloud movements. Further discussion of the implications of variability, e.g. in terms of the size and location of the outflowing gas, will be presented in a forthcoming paper. [ABSTRACT FROM AUTHOR]

Broad absorption lines (BALs) in quasar spectra identify high-velocity outflows that likely exist in all quasars and could play a major role in feedback to galaxy evolution. The variability of BALs can help us understand the structure, evolution and basic physical properties of the outflows. Here we report on our first results from an ongoing BAL monitoring campaign of a sample of 24 luminous quasars at redshifts , focusing on C λ1549 BAL variability in two different time intervals: 4-9 months (short term) and 3.8-7.7 yr (long term) in the quasar rest frame. We find that 39 per cent (7/18) of the quasars varied in the short-term data, whereas 65 per cent (15/23) varied in the long-term data, with a larger typical change in strength in the long-term data. The variability occurs typically in only portions of the BAL troughs. The components at higher outflow velocities are more likely to vary than those at lower velocities, and weaker BALs are more likely to vary than stronger BALs. The fractional change in BAL strength correlates inversely with the strength of the BAL feature, but does not correlate with the outflow velocity. Both the short-term and long-term data indicate the same trends. The observed behaviour is most readily understood as a result of the movement of clouds across the continuum source. If the crossing speeds do not exceed the local Keplerian velocity, then the observed short-term variations imply that the absorbers are <6 pc from the central quasar. [ABSTRACT FROM AUTHOR]

ABSTRACT We report on the discovery of a high-velocity narrow absorption line outflow in the redshift 2.3 quasar J 212329.46 − 005052.9. Five distinct outflow systems are detected with velocity shifts from −9710 to −14 050 km s −1 and C iv λλ1548, 1551 linewidths of FWHM ≈ 62-164 km s −1. This outflow is remarkable for having high speeds and a degree of ionization similar to broad absorption line (BAL) flows, but linewidths 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 superthermal 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. These data require five distinct outflow structures with similar kinematics, physical conditions and characteristic sizes of order 0.01-0.02 pc (based on partial covering). The coordinated line variations, occurring on time-scales ≤0.63 yr (quasar frame), are best explained by global changes in the outflow ionization caused by changes in the quasar's ionizing flux. An upper limit on the acceleration, ≲3 km s −1 yr −1, is consistent with blobs of gas that are gravitationally unbound and coasting freely ≳5 pc from the central black hole. Additional constraints from the variability time indicate that the full range of plausible distances is 5 ≲ R ≲ 1100 pc. However, if these small absorbing structures were created in the inner flow, they should be near the ∼5 pc minimum radius because they can travel just a few pc before dissipating (without external confinement). An apparent double line-lock in C iv suggests that the flow was radiatively accelerated and its present trajectory is within ∼16 ° of the radial (line-of-sight) direction. The absence of strong X-ray absorption shows that radiative shielding in the far-UV and X-rays is not needed to maintain moderate BAL-like ionizations and therefore, apparently, it is not needed to facilitate the radiative acceleration to high speeds. We argue that the ionization is moderated, instead, by high gas densities in small outflow substructures. Finally, we estimate that the kinetic energy yield from this outflow is at least 2 orders of magnitude too low to be important for feedback to the host galaxy's evolution. [ABSTRACT FROM AUTHOR]

We report the first discovery of the emergence of a high-velocity broad-line outflow in a luminous quasar, J105400.40+034801.2, at redshift z∼ 2.1. The outflow is evident in ultraviolet C iv and Si iv absorption lines with velocity shifts v∼ 26 300 km s−1 and deblended widths FWHM ∼4000 km s−1. These features are marginally strong and broad enough to be considered broad absorption lines (BALs), but their large velocities exclude them from the standard BAL definition. The outflow lines appeared between two observations in the years 2002.18 and 2006.96. A third observation in 2008.48 showed the lines becoming ∼40 per cent weaker and 10 to 15 per cent narrower. There is no evidence for acceleration or for any outflow gas at velocities ≲23 000 km s−1. The lines appear to be optically thick, with the absorber covering just 20 per cent of the quasar continuum source. This indicates a characteristic absorber size of , but with a BAL-like total column density and average space density . We attribute the emergence of the outflow lines to a substantial flow structure moving across our line of sight, possibly near the ragged edge of the main BAL flow or possibly related to the onset of a BAL evolutionary phase. [ABSTRACT FROM AUTHOR]

We report on a survey for narrow (full widths at half-minimum <600 km s−1) C iv absorption lines in a sample of bright quasars at redshifts in the Sloan Digital Sky Survey. Our main goal is to understand the relationship of narrow C iv absorbers to quasar outflows and, more generally, to quasar environments. We determine velocity zero-points using the broad Mg ii emission line, and then measure the absorbers' quasar-frame velocity distribution. We examine the distribution of lines arising in quasar outflows by subtracting model fits to the contributions from cosmologically intervening absorbers and absorption due to the quasar host galaxy or cluster environment. We find that a substantial number ( per cent) of absorbers with Å in the velocity range km s−1 are intrinsic to the active galactic nucleus outflow. This ‘outflow fraction’ peaks near km s−1 with a value of . At velocities below km s−1, the incidence of outflowing systems drops, possibly due to geometric effects or to the over-ionization of gas that is nearer the accretion disc. Furthermore, we find that outflow absorbers are on average broader and stronger than cosmologically intervening systems. Finally, we find that ∼14 per cent of the quasars in our sample exhibit narrow, outflowing C iv absorption with Å, slightly larger than that for broad absorption line systems. [ABSTRACT FROM AUTHOR]

The Sphinx machine [F. Lassalle et al., “Status on the SPHINX machine based on the 1microsecond LTD technology”] based on microsecond linear transformer driver (LTD) technology is used to implode an aluminium wire array with an outer diameter up to 140 mm and maximum current from 3.5 to 5 MA. 700 to 800 ns implosion Z-pinch experiments are performed on this driver essentially with aluminium. Best results obtained before the improvement described in this paper were 1–3 TW radial total power, 100–300 kJ total yield, and 20–30 kJ energy above 1 keV. An auxiliary generator was added to the Sphinx machine in order to allow a multi microsecond current to be injected through the wire array load before the start of the main current. Amplitude and duration of this current prepulse are adjustable, with maxima ∼10 kA and 50 μs. This prepulse dramatically changes the ablation phase leading to an improvement of the axial homogeneity of both the implosion and the final radiating column. Total power was multiplied by a factor of 6, total yield by a factor of 2.5 with a reproducible behavior. This paper presents experimental results, magnetohydrodynamic simulations, and analysis of the effect of such a long current prepulse. [ABSTRACT FROM AUTHOR]

Background and purpose: The use of recombinant tissue plasminogen activator (rt-PA) is a proven therapy in acute stroke. Main concerns are based on hemorrhagic complications, which are connected with microvascular integrity loss. The aim of this study was to evaluate microvascular changes after various doses of rt-PA. Methods and results: Focal cerebral ischemia for 3 hours was induced using the suture model in rats and followed by 24 hours of reperfusion. Six rats received either saline, 0.9, 9, or 18 mg rtPA/kg body weight at the end of ischemia. By immunostaining of collagen type IV the density of microvessels and the total stained area in the basal ganglia and cortex was measured. Comparison of the ischemic with the non-ischemic hemisphere showed significantly less reduction of the number of microvessels in rats treated with low-dose rt-PA than in the other groups: controls 17 ± 3% (basal ganglia), 12 ± 7% (cortex); 0.9 mg rt-PA, 18 ± 3%, 10 ± 4%; 9 mg, 21 ± 4%, 13 ± 7%; 18 mg, 22 ± 4%, 15 ± 8%. A similar effect was observed on the total stained area: control 25 ± 4% (basal ganglia), 14 ± 7% (cortex); 0.9 mg rt-PA, 23 ± 2%, 7 ± 4%; 9 mg, 28 ± 4%, 15 ± 4%; 18 mg, 29 ± 4%, 17 ± 5%, p<0.001. The significant reduction of the area of infarction after low and moderate doses of rt-PA was visualized with an MAP2-antibody, and the volume was calculated by 3-D reconstruction: control, 165.2 mm 3 ± 21%; 0.9 mg rt-PA, 102.6 mm 3 ± 16%; 9 mg, 101.2 mm 3 ± 17%; 18 mg, 133.0 mm 3 ± 24%; p < 0.001. Conclusions: Rats exposed to low-dose rt-PA preserved basal lamina structures, and showed smaller infarct sizes. The protective effect of low-dose rt-PA might be due to an increased microvascular patency rate. [ABSTRACT FROM AUTHOR]

Intercomparison of the spectra of seven high-luminosity quasi-stellar objects (QSOs) shows that there is a gradation of properties in their broad emission-line regions (BELRs) that can be understood as differing mixtures of different gas components. Six of these seven objects have unusually narrow BELR profiles, which greatly facilitates the disentangling of blends and measuring of weak lines. In the QSO 0207 - 398, the BELR is made up of at least three kinematically distinct components; its spectrum is in fact a composite of the spectra of the more homogeneous BELRs in the QSOs at either end of our sequence of properties. This paper focuses on the properties of the line-emitting region in Q0207 - 398 dubbed component "A," which has sharp (FWHM = 1000 km s^-1^), symmetric line profiles centered at zero velocity. We find that these lines are emitted in very dense (n_H_ ~ 10^12.5^ cm^-3^) gas at a characteristic radius r ~ 10^17.7^ cm from the continuum source and which emits a low-ionization spectrum including strong A1 III λ1857. The second component, "B," in Q0207 - 398 is the subject of a companion paper. It is characterized by high-ionization lines such as N V λ1240, O VI λ1034, and C IV λ1549 with profiles that peak at zero velocity but have a blue tail extending out to - 11,000 km s^-1^. It receives about the same incident flux as component A and therefore may lie at the same distance from the continuum source, but it is significantly less dense (n_H_ ~ 10^11^ cm^-3^). The remaining line emission from Q0207 - 398 is attributed to a component "C" which has reasonably broad (FWHM = 2000 km s^-1^), symmetric line profiles centered at zero velocity. Most of the Lyα and C III] λ1909 emission comes from this region, but it also contributes to C IV, N V, and many other lines. The spectrum of component C is in fact quite similar to that of "normal" QSOs. We interpret component A as the dense source for radiatively accelerated, outward flowing gas which we see as component B. Component A may consist of the ablated atmospheres of stars which have strayed too close to the QSO nucleus. In addition, component A's velocity width is essentially the same as that of the stellar population in the nucleus of M87. From the radius and velocity, we infer the presence of a central mass of only 10^7^-10^8^ M_sun_, if we are measuring virial motions and if the ionizing continuum is isotropic. An alternate possibility is that the narrow single-peaked component A profile comes from a rotating torus/accretion disk, probably seen face-on, in which case it is impossible to measure the central mass. We discuss the similarity between Mg II-type broad absorption line (BAL) QSOs and Q0207 - 398, which does not have BALs. In fact, the two Mg II-type BAL objects in our sample have spectra almost exactly like that of Q0207 - 398, except that component B is seen in absorption rather than in emission., Astronomy