WorldWideScience

Sample records for quasar outflow contribution

  1. Contribution of quasar-driven outflows to the extragalactic gamma-ray background

    Science.gov (United States)

    Wang, Xiawei; Loeb, Abraham

    2016-12-01

    The origin of the extragalactic γ-ray background permeating throughout the Universe remains a mystery forty years after its discovery. The extrapolated population of blazars can account for only half of the background radiation in the energy range of ~0.1-10 GeV (refs ,). Here we show that quasar-driven outflows generate relativistic protons that produce the missing component of the extragalactic γ-ray background and naturally match its spectral fingerprint, with a generic break above ~1 GeV. The associated γ-ray sources are too faint to be detected individually, explaining why they had not been identified so far. However, future radio observations may image their shock fronts directly. Our best fit to the Fermi-LAT observations of the extragalactic γ-ray background spectrum provides constraints on the outflow parameters that agree with observations of these outflows and theoretical predictions. Although our model explains the data, there might be additional contributing sources.

  2. Metallicity and Quasar Outflows

    CERN Document Server

    Wang, Huiyuan; Yuan, Weimin; Wang, Tinggui

    2012-01-01

    Correlations are investigated of the outflow strength of quasars, as measured by the blueshift and asymmetry index (BAI) of the CIV line (Wang et al. 2011), with intensities and ratios of broad emission lines, based on composite quasar spectra built from the Sloan Digital Sky Survey. We find that most of the line ratios of other ions to CIV prominently increases with BAI. These behaviors can be well understood in the context of increasing metallicity with BAI. The strength of dominant coolant, CIV line, decreases and weak collisionally excited lines increase with gas metallicity as a result of the competition between different line coolants. Using SiIV+OIV]/CIV as an indicator of gas metallicity, we present, for the first time, a strong correlation between the metallicitiy and the outflow strength of quasars over a wide range of 1.7 to 6.9 times solar abundance. Our result implies that the metallicity plays an important role in the formation of quasar outflows, likely via affecting outflow acceleration. This ...

  3. Emergence of a Quasar Outflow

    CERN Document Server

    Hamann, F; Hidalgo, P Rodriguez; Prochaska, J X; Herbert-Fort, S

    2008-01-01

    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 CIV and SiIV absorption lines with velocity shifts v ~ 26,300 km/s and deblended widths FWHM ~ 4000 km/s. 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% weaker and 10% to 15% narrower. There is no evidence for acceleration or for any outflow gas at velocities 21.2 and average space density n_H > 2 x 10^5 cm^-3. 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.

  4. Outflows of stars due to quasar feedback

    CERN Document Server

    Zubovas, Kastytis; Sazonov, Sergey; Sunyaev, Rashid

    2013-01-01

    Quasar feedback outflows are commonly invoked to drive gas out of galaxies in the early gas-rich epoch to terminate growth of galaxies. Here we present simulations that show that AGN feedback may drive not only gas but also stars out of their host galaxies under certain conditions. The mechanics of this process is as following: (1) AGN-driven outflows accelerate and compress gas filling the host galaxy; (2) the accelerated dense shells become gravitationally unstable and form stars on radial trajectories. For the spherically symmetric initial conditions explored here, the black hole needs to exceed the host's M_sigma mass by a factor of a few to accelerate the shells and the new stars to escape velocities. We discuss potential implications of these effects for the host galaxies: (i) radial mixing of bulge stars with the rest of the host; (ii) contribution of quasar outflows to galactic fountains as sources of high-velocity clouds; (iii) wholesale ejection of hyper velocity stars out of their hosts, giving ris...

  5. Intergalactic Magnetic Fields from Quasar Outflows

    CERN Document Server

    Furlanetto, S; Furlanetto, Steven; Loeb, Abraham

    2001-01-01

    Outflows from quasars inevitably pollute the intergalactic medium (IGM) with magnetic fields. The short-lived activity of a quasar leaves behind an expanding magnetized bubble in the IGM. We model the expansion of the remnant quasar bubbles and calculate their distribution as a function of size and magnetic field strength at different redshifts. We generically find that by a redshift z=3, about 5-20% of the IGM volume is filled by magnetic fields with an energy density >10% of the mean thermal energy density of a photo-ionized IGM (at T=10^4 K). As massive galaxies and X-ray clusters condense out of the magnetized IGM, the adiabatic compression of the magnetic field could result in the field strength observed in these systems without a need for further dynamo amplification. The intergalactic magnetic field could also provide a nonthermal contribution to the pressure of the photo-ionized gas that may account for the claimed discrepancy between the simulated and observed Doppler width distributions of the Ly-al...

  6. An Intergalactic Magnetic Field from Quasar Outflows

    CERN Document Server

    Furlanetto, S; Furlanetto, Steven; Loeb, Abraham

    2001-01-01

    Outflows from quasars inevitably pollute the intergalactic medium (IGM) with magnetic fields. The short-lived activity of a quasar leaves behind an expanding magnetized bubble in the IGM. We model the expansion of the remnant quasar bubbles and calculate their distribution as a function magnetic field strength at different redshifts. We find that by a redshift z ~ 3, about 5-80% of the IGM volume is filled by magnetic fields with an energy density > 10% of the mean thermal energy density of a photo-ionized IGM (at ~ 10^4 K). As massive galaxies and X-ray clusters condense out of the magnetized IGM, the adiabatic compression of the magnetic field could result in the fields observed in these systems without a need for further dynamo amplification.

  7. Quasar feedback revealed by giant molecular outflows

    CERN Document Server

    Feruglio, Chiara; Piconcelli, Enrico; Menci, Nicola; Aussel, Herve'; Lamastra, Alessandra; Fiore, Fabrizio

    2010-01-01

    In the standard scenario for galaxy evolution the transformation of young star-forming galaxies into red bulge-dominated spheroids, where star formation has been quenched, is often explained by invoking a strong negative feedback generated by accretion onto a central super-massive black hole. The depletion of gas resulting from quasar-driven outflows should eventually stop star-formation across the host galaxy and lead to the black hole "suicide" for starvation. Direct observational evidence for a major quasar feedback onto the host galaxy is still missing, since outflows previously observed in quasars are associated with the ionized component of the gas, which only accounts for a minor fraction of the total gas content, and typically occur in the central regions. We used the IRAM PdBI to observe the CO(1-0) transition in Mrk 231, the closest quasar known. We detect broad wings of the CO line, with velocities up to 750 km/s and spatially resolved on the kpc scale. Such broad CO wings trace a giant molecular o...

  8. OUTFLOW AND HOT DUST EMISSION IN HIGH-REDSHIFT QUASARS

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Huiyuan; Xing, Feijun; Wang, Tinggui; Zhou, Hongyan [Key Laboratory for Research in Galaxies and Cosmology, Department of Astronomy, University of Science and Technology of China, Chinese Academy of Sciences, Hefei, Anhui 230026 (China); Zhang, Kai [Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030 (China); Zhang, Shaohua, E-mail: whywang@mail.ustc.edu.cn [Polar Research Institute of China, Jinqiao Road 451, Shanghai 200136 (China)

    2013-10-10

    Correlations of hot dust emission with outflow properties are investigated, based on a large z ∼ 2 non-broad absorption line quasar sample built from the Wide-field Infrared Survey and the Sloan Digital Sky Survey data releases. We use the near-infrared slope and the infrared to UV luminosity ratio to indicate the hot dust emission relative to the emission from the accretion disk. In our luminous quasars, these hot dust emission indicators are almost independent of the fundamental parameters, such as luminosity, Eddington ratio and black hole mass, but moderately dependent on the blueshift and asymmetry index (BAI) and FWHM of C IV lines. Interestingly, the latter two correlations dramatically strengthen with increasing Eddington ratio. We suggest that, in high Eddington ratio quasars, C IV regions are dominated by outflows so the BAI and FWHM (C IV) can reliably reflect the general properties and velocity of outflows, respectively. In low Eddington ratio quasars, on the other hand, C IV lines are primarily emitted by virialized gas so the BAI and FWHM (C IV) become less sensitive to outflows. Therefore, the correlations for the highest Eddington ratio quasars are more likely to represent the true dependence of hot dust emission on outflows and the correlations for the entire sample are significantly diluted by the low Eddington ratio quasars. Our results show that an outflow with a large BAI or velocity can double the hot dust emission on average. We suggest that outflows either contain hot dust in themselves or interact with the dusty interstellar medium or torus.

  9. Line-driven radiative outflows in luminous quasars

    CERN Document Server

    Bowler, Rebecca A A; Allen, James T; Ferland, Gary J

    2014-01-01

    An analysis of ~19500 narrow (<200 km/s) CIV 1548.2,1550.8 absorbers in ~34000 Sloan Digital Sky Survey quasar spectra is presented. The statistics of the number of absorbers as a function of outflow-velocity shows that in approximately two-thirds of outflows, with multiple CIV absorbers present, absorbers are line-locked at the 500 km/s velocity separation of the CIV absorber doublet; appearing as 'triplets' in the quasar spectra. Line-locking is an observational signature of radiative line driving in outflowing material, where the successive shielding of 'clouds' of material in the outflow locks the clouds together in outflow velocity. Line-locked absorbers are seen in both broad absorption line quasars (BALs) and non-BAL quasars with comparable frequencies and with velocities out to at least 20000 km/s. There are no detectable differences in the absorber properties and the dust content of single CIV doublets and line-locked CIV doublets. The gas associated with both single and line-locked CIV absorption...

  10. A Variable PV Broad Absorption Line and Quasar Outflow Energetics

    CERN Document Server

    Capellupo, Daniel M; Barlow, Tom A

    2014-01-01

    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 $z_e = 2.56$), aided by the first detection of PV $\\lambda\\lambda$1118,1128 BAL variability in a quasar. In particular, PV absorption at velocities where the CIV trough does not reach zero intensity implies that the CIV BAL is saturated and the absorber only partially covers the background continuum source (with characteristic size 22.3 (cm^-2). Variability in the PV and saturated CIV BALs strongly disfavors 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 ...

  11. Outflow and hot dust emission in broad absorption line quasars

    CERN Document Server

    Zhang, Shaohua; Wang, Tinggui; Xing, Feijun; Zhang, Kai; Zhou, Hongyan; Jiang, Peng

    2014-01-01

    We have investigated a sample of 2099 broad absorption line (BAL) quasars with z=1.7-2.2 built from the Sloan Digital Sky Survey Data Release Seven and the Wide-field Infrared Survey. This sample is collected from two BAL quasar samples in the literature, and refined by our new algorithm. Correlations of outflow velocity and strength with hot dust indicator (beta_NIR) and other quasar physical parameters, such as Eddington ratio, luminosity and UV continuum slope, are explored in order to figure out which parameters drive outflows. Here beta_NIR is the near-infrared continuum slope, a good indicator of the amount of hot dust emission relative to accretion disk emission. We confirm previous findings that outflow properties moderately or weakly depends on Eddington ratio, UV slope and luminosity. For the first time, we report moderate and significant correlations of outflow strength and velocity with beta_NIR in BAL quasars. It is consistent with the behavior of blueshifted broad emission lines in non-BAL quasa...

  12. Outflow and hot dust emission in high redshift quasars

    CERN Document Server

    Wang, Huiyuan; Zhang, Kai; Wang, Tinggui; Zhou, Hongyan; Zhang, Shaohua

    2013-01-01

    Correlations of hot dust emission with outflow properties are investigated, based on a large z~2 non-BAL quasar sample built from the Wide-field Infrared Survey and the Sloan Digital Sky Survey data releases. We use the near infrared (NIR) slope and the infrared to UV luminosity ratio to indicate the hot dust emission relative to the emission from accretion disk. In our luminous quasars, these hot dust emission indicators are almost independent of the fundamental parameters, such as luminosity, Eddington ratio and black hole mass, but moderately dependent on the blueshift and asymmetry index (BAI) and FWHM of CIV lines. Interestingly, the latter two correlations dramatically strengthen with increasing Eddington ratio. We suggest that, in high Eddington ratio quasars, CIV regions are dominated by outflows so BAI and FWHM(CIV) can reliably reflect the general property and velocity of outflows, respectively. While in low Eddington ratio quasars, CIV lines are primarily emitted by virialized gas so BAI and FWHM(C...

  13. The Physics and Physical Properties of Quasar Outflows

    CERN Document Server

    Hamann, Fred; Chartas, George; McGraw, Sean; Hidalgo, Paola Rodriguez; Shields, Joseph; Charlton, Jane; Eracleous, Michael

    2013-01-01

    We describe two studies designed to characterize the total column densities, kinetic energies, and acceleration physics of broad absorption line (BAL) outflows in quasars. The first study uses new Chandra X-ray and ground-based rest-frame UV observations of 7 quasars with mini-BALs at extreme high speeds, in the range 0.1c to 0.2c, to test the idea that strong radiative shielding is needed to moderate the mini-BAL ionizations and facilitate their acceleration to extreme speeds. We find that the X-ray absorption is weak or absent, with generally N_H 15% of the UV continuum source along our lines of sight (based on measured line depths), then the radial thickness of these outflows is only Delta_R 8 x 10^15 cm. Thus the outflow regions have the shape of very thin "pancakes" viewed face-on, or they occupy larger volumes like a spray of dense cloudlets with a very small volume filling factor. We speculate that this situation (with ineffective shielding and small dense outflow substructures) applies to most quasar...

  14. Heating of the Intracluster Medium by Quasar Outflows

    Indian Academy of Sciences (India)

    Suparna Roychowdhury; Biman B. Nath

    2002-03-01

    We study the possibility of quasar outflows in clusters and groups of galaxies heating the intracluster gas in order to explain the recent observation of excess entropy in this gas. We show that radio galaxies alone cannot provide the energy required to explain the observations but the inclusion of Broad Absorption Line (BAL) outflows can do so, and that in this scenario most of the heating takes place at ∼ 1–4, the ``preheating” epoch being at a lower redshift for lower mass clusters.

  15. Fast outflows and star formation quenching in quasar host galaxies

    CERN Document Server

    Carniani, S; Maiolino, R; Balmaverde, B; Brusa, M; Cano-Díaz, M; Cicone, C; Comastri, A; Cresci, G; Fiore, F; Feruglio, C; La Franca, F; Mainieri, V; Mannucci, F; Nagao, T; Netzer, H; Piconcelli, E; Risaliti, G; Schneider, R; Shemmer, O

    2016-01-01

    Negative feedback from active galactic nuclei (AGN) is considered a key mechanism in shaping galaxy evolution. Fast, extended outflows are frequently detected in the AGN host galaxies at all redshifts and luminosities, both in ionised and molecular gas. However, these outflows are only "potentially" able to quench star formation and we are still missing a decisive evidence of negative feedback in action. Here we present Spectrograph for INtegral Field Observations in the Near Infrared (SINFONI) H- and K-band integral-field spectroscopic observations of two quasars at $z\\sim$2.4 characterised by fast, extended outflows detected through the [OIII]$\\lambda$5007 line (Carniani et al. 2015). The high signal-to-noise ratio of our observations allows us to identify faint narrow (FWHM $< 500$ km/s), and spatially extended components in [OIII]$\\lambda$5007 and H$\\alpha$ emission associated with star formation in the host galaxy. Such star-formation powered emission is spatially anti-correlated with the fast outflow...

  16. Ultra high energy cosmic rays from non-relativistic quasar outflows

    CERN Document Server

    Wang, Xiawei

    2016-01-01

    It has been suggested that non-relativistic outflows from quasars can naturally account for the missing component of the extragalactic $\\gamma$-ray background and explain the cumulative neutrino background through pion decay in collisions between protons accelerated by the outflow shock and interstellar protons. Here we show that the same quasar outflows are capable of accelerating protons to energies of $\\sim 10^{20}$ eV during the early phase of their propagation. The overall quasar population is expected to produce a cumulative ultra high energy cosmic ray flux of $\\sim10^{-7}\\,\\rm GeV\\,cm^{-2}s^{-1}sr^{-1}$ at $E_{\\rm CR}\\gtrsim10^{18}$ eV. The spectral shape and amplitude is consistent with recent observations for outflow parameters constrained to fit secondary $\\gamma$-rays and neutrinos without any additional parameter tuning. This indicates that quasar outflows simultaneously account for all three messengers at their observed levels.

  17. Discovery of Universal Elliptical Outflow Structures in Radio-Quiet Quasars

    CERN Document Server

    Lovegrove, Justin; Leiter, Darryl

    2010-01-01

    Fifty-nine quasars in the background of the Magellanic Clouds had brightness records monitored by the MACHO project during the years 1992 - 99. Because the circumpolar fields of these quasars had no seasonal sampling defects, their observation produced data sets well suited to further careful analysis. Following a preliminary report wherein we showed the existence of reverberation in the data for one of the radio-quiet quasars in this group, we now show that similar reverberations have been seen in all of the 55 radio-quiet quasars with adequate data, making possible the determination of the quasar inclination to the observer's line of sight. The reverberation signatures indicate the presence of large-scale elliptical outflow structures similar to that predicted by the Elvis (2000) and "dusty torus" models of quasars, whose characteristic sizes vary within a surprisingly narrow range of scales. More importantly the observed opening angle relative to the polar axis of the universal elliptical outflow structure...

  18. Fast Molecular Outflows in Luminous Galaxy Mergers: Evidence for Quasar Feedback from Herschel

    Science.gov (United States)

    Veilleux, S.; Melendez, M.; Sturm, E.; Garcia-Carpio, J.; Fischer, J.; Gonzalez-Alfonso, E.; Contursi, A.; Lutz, D.; Poglitsch, A.; Davies, R.; Genzel, R.; Tacconi, L.; deJong, J. A.; Sternberg, A.; Netzer, H.; Hailey-Dunsheath, S.; Verma, A.; Rupke, D. S. N.; Maiolino, R.; Teng, S. H.; Polisensky, E.

    2013-01-01

    We report the results from a systematic search for molecular (OH 119 micron) outflows with Herschel/PACS in a sample of 43 nearby (z 11.8 +/- 0.3]. The quasars in these systems play a dominant role in driving the molecular outflows. However, the most AGN dominated systems, where OH is seen purely in emission, show relatively modest OH line widths, despite their large AGN luminosities, perhaps indicating that molecular outflows subside once the quasar has cleared a path through the obscuring material.

  19. Far-infrared emission in luminous quasars accompanied by nuclear outflows

    Science.gov (United States)

    Maddox, Natasha; Jarvis, M. J.; Banerji, M.; Hewett, P. C.; Bourne, N.; Dunne, L.; Dye, S.; Eales, S.; Furlanetto, C.; Maddox, S. J.; Smith, M. W. L.; Valiante, E.

    2017-09-01

    Combining large-area optical quasar surveys with the new far-infrared (FIR) Herschel-ATLAS Data Release 1, we search for an observational signature associated with the minority of quasars possessing bright FIR luminosities. We find that FIR-bright quasars show broad C IV emission-line blueshifts in excess of that expected from the optical luminosity alone, indicating particularly powerful nuclear outflows. The quasars show no signs of having redder optical colours than the general ensemble of optically selected quasars, ruling out differences in line-of-sight dust within the host galaxies. We postulate that these objects may be caught in a special evolutionary phase, with unobscured, high black hole accretion rates and correspondingly strong nuclear outflows. The high FIR emission found in these objects is then either a result of star formation related to the outflow, or is due to dust within the host galaxy illuminated by the quasar. We are thus directly witnessing coincident small-scale nuclear processes and galaxy-wide activity, commonly invoked in galaxy simulations that rely on feedback from quasars to influence galaxy evolution.

  20. Evidence for Fluorescent Fe II Emission from Extended Low Ionization Outflows in Obscured Quasars

    Science.gov (United States)

    Wang, Tinggui; Ferland, Gary J.; Yang, Chenwei; Wang, Huiyuan; Zhang, Shaohua

    2016-06-01

    Recent studies have shown that outflows in at least some broad absorption line (BAL) quasars are extended well beyond the putative dusty torus. Such outflows should be detectable in obscured quasars. We present four WISE selected infrared red quasars with very strong and peculiar ultraviolet Fe ii emission lines: strong UV Fe ii UV arising from transitions to ground/low excitation levels, and very weak Fe ii at wavelengths longer than 2800 Å. The spectra of these quasars display strong resonant emission lines, such as C iv, Al iii and Mg ii but sometimes, a lack of non-resonant lines such as C iii], S iii and He ii. We interpret the Fe ii lines as resonantly scattered light from the extended outflows that are viewed nearly edge-on, so that the accretion disk and broad line region are obscured by the dusty torus, while the extended outflows are not. We show that dust free gas exposed to strong radiation longward of 912 Å produces Fe ii emission very similar to that observed. The gas is too cool to collisionally excite Fe ii lines, accounting for the lack of optical emission. The spectral energy distribution from the UV to the mid-infrared can be modeled as emission from a clumpy dusty torus, with UV emission being reflected/scattered light either by the dusty torus or the outflow. Within this scenario, we estimate a minimum covering factor of the outflows from a few to 20% for the Fe ii scattering region, suggesting that Fe ii BAL quasars are at a special stage of quasar evolution.

  1. The most powerful quasar outflows as revealed by the Civ {\\lambda}1549 resonance line

    CERN Document Server

    Marziani, P; Sulentic, J W; del Olmo, A; Stirpe, G M; Dultzin, D

    2015-01-01

    While quasar outflows may be quasi-ubiquitous, there are significant differences on a source-by- source basis. These differences can be organized along the 4D Eigenvector 1 sequence: at least at low z, with only Population A sources radiating at relatively high Eddington ratio and showing prominent high-velocity outflows in Civ {\\lambda}1549 line profiles. We discuss in this paper VLT-FORS observations of Civ {\\lambda}1549 emission line profiles for a high-luminosity sample of Hamburg- ESO quasars and how they are affected by outflow motion as a function of quasar luminosity. Our high- luminosity sample has the notable advantage that the rest frame has been accurately determined from previous VLT-ISAAC observations of H{\\beta} in the J, H, and K bands. This makes measures of inter-line velocity shifts accurate and free of systemic biases. As the redshift increases and the luminosity of the brightest quasars increases, powerful, high-velocity outflows become more frequent. We discuss the outflow contextualisat...

  2. An ultra-dense fast outflow in a quasar at z=2.4

    CERN Document Server

    Williams, R J; Krongold, Y; Carniani, S; Cresci, G; Mannucci, F; Marconi, A

    2016-01-01

    We present Adaptive Optics assisted near-IR integral field spectroscopic observations of a luminous quasar at $z = 2.4$, previously observed as the first known example at high redshift of large scale quasar-driven outflow quenching star formation in its host galaxy. The nuclear spectrum shows broad and blueshifted H$\\beta$ in absorption, which is tracing outflowing gas with high densities ($>10^8$ - $10^9$ cm$^{-3}$) and velocities in excess of 10,000 km s$^{-1}$. The properties of the outflowing clouds (covering factor, density, column density and inferred location) indicate that they likely originate from the Broad Line Region. The energetics of such nuclear regions are consistent with that observed in the large scale outflow, supporting models in which quasar driven outflows originate from the nuclear region and are energy conserving. We note that the asymmetric profile of both the H$\\beta$ and H$\\alpha$ emission lines is likely due to absorption by the dense outflowing gas along the line of sight. This ou...

  3. Probing Quasar Outflows with Intrinsic Narrow Absorption Lines

    CERN Document Server

    Misawa, T; Charlton, J C; Ganguly, R; Tytler, D; Kirkman, D; Suzuki, N; Lubin, D

    2006-01-01

    We present statistical and monitoring results of narrow absorption lines that are physically related to quasars (i.e., intrinsic NALs). We use Keck/HIRES spectra of 37 optically bright quasars at z=2-4, and identify 150 NAL systems that contain 124 C IV, 12 N V, and 50 Si IV doublets. Among them, 39 are classified as intrinsic systems based on partial coverage analysis. At least 50% of quasars host intrinsic NALs. We identify two families of intrinsic systems based on their ionization state. Some intrinsic systems have detectable low-ionization NALs at similar velocities as higher-ionization NALs, although such low-ionization lines are rare in broad absorption line (BAL) systems. We also have observed an optically bright quasar, HS1603+3820, eight times with Subaru/HDS and HET/MRS over an interval of 4.2 years (1.2 years in the quasar rest frame), for the purpose of monitoring a variable C IV mini-BAL system. We find that all the troughs of the system vary in concert. However, no other correlations are seen b...

  4. A Massive X-ray Outflow From The Quasar PDS 456

    Science.gov (United States)

    Reeves, J. N.; O'Brien, P. T.; Ward, M. J.

    2003-01-01

    We report on XMM-Newton spectroscopic observations of the luminous, radio-quiet quasar PDS 456. The hard X-ray spectrum of PDS 456 shows a deep absorption trough (constituting 50% of the continuum) at energies above 7 keV in the quasar rest frame, which can be attributed to a series of blue-shifted K-shell absorption edges due to highly ionized iron. The higher resolution soft X-ray grating RGS spectrum exhibits a broad absorption line feature near 1 keV, which can be modeled by a blend of L-shell transitions from highly ionized iron (Fe XVII - XXIV). An extreme outflow velocity of approx. 50000 km/s is required to model the K and L shell iron absorption present in the XMM-Newton data. Overall, a large column density (N(sub H) = 5 x 10(exp 23)/sq cm) of highly ionized gas (log xi = 2.5) is required in PDS 456. A large mass outflow rate of approx. 10 solar mass/year (assuming a conservative outflow covering factor of 0.1 steradian) is derived, which is of the same order as the overall mass accretion rate in PDS 456. This represents a substantial fraction (approx. 10%) of the quasar energy budget, whilst the large column and outflow velocity place PDS 456 towards the extreme end of the broad absorption line quasar population.

  5. Evidence for Fluorescent Fe II Emission from Extended Low Ionization Outflows in Obscured Quasars

    CERN Document Server

    Wang, Tinggui; Yang, Chenwei; Wang, Huiyuan; Zhang, Shaohua

    2016-01-01

    Recent studies have shown that outflows in at least some broad absorption line (BAL) quasars are extended well beyond the putative dusty torus. Such outflows should be detectable in obscured quasars. We present four WISE selected infrared red quasars with very strong and peculiar ultraviolet Fe ii emission lines: strong UV Fe II UV arising from transitions to ground/low excitation levels, and very weak Fe II at wavelengths longer than 2800 {\\AA}. The spectra of these quasars display strong resonant emission lines, such as C IV, Al III and Mg II but sometimes, a lack of non-resonant lines such as C III], S III and He II. We interpret the Fe II lines as resonantly scattered light from the extended outflows that are viewed nearly edge-on, so that the accretion disk and broad line region are obscured by the dusty torus, while the extended outflows are not. We show that dust free gas exposed to strong radiation longward of 912 {\\AA} produces Fe II emission very similar to that observed. The gas is too cool to coll...

  6. GBT Detection of Polarization-dependent HI Absorption and HI Outflows in Local ULIRGs and Quasars

    CERN Document Server

    Teng, Stacy H; Baker, Andrew J

    2013-01-01

    We present the results of a 21-cm HI survey of 27 local massive gas-rich late-stage mergers and merger remnants with the Robert C. Byrd Green Bank Telescope (GBT). These remnants were selected from the Quasar/ULIRG Evolution Study (QUEST) sample of ultraluminous infrared galaxies (ULIRGs; L$_{8-1000 \\mu m} > 10^{12}$ L$_\\odot$) and quasars; our targets are all bolometrically dominated by active galactic nuclei (AGN) and sample the later phases of the proposed ULIRG-to-quasar evolutionary sequence. We find the prevalence of HI absorption (emission) to be 100% (29%) in ULIRGs with HI detections, 100% (88%) in FIR-strong quasars, and 63% (100%) in FIR-weak quasars. The absorption features are associated with powerful neutral outflows that change from being mainly driven by star formation in ULIRGs to being driven by the AGN in the quasars. These outflows have velocities that exceed 1500 km s$^{-1}$ in some cases. Unexpectedly, we find polarization-dependent HI absorption in 57% of our spectra (88% and 63% of the...

  7. GBT Detection of Polarization-Dependent HI Absorption and HI Outflows in Local ULIRGs and Quasars

    Science.gov (United States)

    Teng, Stacy H.; Veilleux, Sylvain; Baker, Andrew J.

    2013-01-01

    We present the results of a 21-cm HI survey of 27 local massive gas-rich late-stage mergers and merger remnants with the Green Bank Telescope (GBT). These remnants were selected from the Quasar/ULIRG Evolution Study (QUEST) sample of ultraluminous infrared galaxies (ULIRGs; L(sub 8 - 1000 micron) > 10(exp 12) solar L) and quasars; our targets are all bolometrically dominated by active galactic nuclei (AGN) and sample the later phases of the proposed ULIRG-to-quasar evolutionary sequence. We find the prevalence of HI absorption (emission) to be 100% (29%) in ULIRGs with HI detections, 100% (88%) in FIR-strong quasars, and 63% (100%) in FIR-weak quasars. The absorption features are associated with powerful neutral outflows that change from being mainly driven by star formation in ULIRGs to being driven by the AGN in the quasars. These outflows have velocities that exceed 1500 km/s in some cases. Unexpectedly, we find polarization-dependent HI absorption in 57% of our spectra (88% and 63% of the FIR-strong and FIR-weak quasars, respectively). We attribute this result to absorption of polarized continuum emission from these sources by foreground HI clouds. About 60% of the quasars displaying polarized spectra are radio-loud, far higher than the approx 10% observed in the general AGN population. This discrepancy suggests that radio jets play an important role in shaping the environments in these galaxies. These systems may represent a transition phase in the evolution of gas-rich mergers into "mature" radio galaxies.

  8. Powerful quasar outflow in a massive disc galaxy at $z \\sim 5$

    CERN Document Server

    Curtis, Michael

    2016-01-01

    There is growing observational evidence of high-redshift quasars launching energetic, fast outflows, but the effects that these have on their host galaxies is poorly understood. We employ the moving-mesh code AREPO to study the feedback from a quasar that has grown to $\\sim 10^9 M_\\odot$ by $z \\sim 5$ and the impact that this has on its host galaxy. Our simulations use a super-Lagrangian refinement technique to increase the accuracy with which the interface of the quasar-driven wind and the surrounding gas is resolved. We find that the feedback injected in these simulations is less efficient at removing gas from the galaxy than in previous work using the same feedback strength, and that this leads to the growth of a massive, rotationally supported, star-forming disc, co-existing with a powerful quasar-driven outflow. The properties of our host galaxy, including the kinematical structure of the gaseous disc and of the outflow, are in good agreement with current observations. Upcoming ALMA and JWST observations...

  9. FAST MOLECULAR OUTFLOWS IN LUMINOUS GALAXY MERGERS: EVIDENCE FOR QUASAR FEEDBACK FROM HERSCHEL

    Energy Technology Data Exchange (ETDEWEB)

    Veilleux, S.; Meléndez, M. [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Sturm, E.; Gracia-Carpio, J.; Contursi, A.; Lutz, D.; Poglitsch, A.; Davies, R.; Genzel, R.; Tacconi, L.; De Jong, J. A. [Max-Planck-Institute for Extraterrestrial Physics (MPE), Giessenbachstrasse 1, D-85748 Garching (Germany); Fischer, J. [Naval Research Laboratory, Remote Sensing Division, 4555 Overlook Avenue SW, Washington, DC 20375 (United States); González-Alfonso, E. [Departamento de Física y Matemáticas, Universidad de Alcalá, Campus Universitario, E-28871 Alcalá de Henares, Madrid (Spain); Sternberg, A.; Netzer, H. [Sackler School of Physics and Astronomy, Tel Aviv University, Ramat Aviv 69978 (Israel); Hailey-Dunsheath, S. [Department of Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Verma, A. [Department of Astrophysics, Oxford University, Oxford OX1 3RH (United Kingdom); Rupke, D. S. N. [Department of Physics, Rhodes College, Memphis, TN 38112 (United States); Maiolino, R. [Cavendish Laboratory, University of Cambridge, 19 J.J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Teng, S. H., E-mail: veilleux@astro.umd.edu, E-mail: marcio@astro.umd.edu [Observational Cosmology Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); and others

    2013-10-10

    We report the results from a systematic search for molecular (OH 119 μm) outflows with Herschel/PACS in a sample of 43 nearby (z < 0.3) galaxy mergers, mostly ultraluminous infrared galaxies (ULIRGs) and QSOs. We find that the character of the OH feature (strength of the absorption relative to the emission) correlates with that of the 9.7 μm silicate feature, a measure of obscuration in ULIRGs. Unambiguous evidence for molecular outflows, based on the detection of OH absorption profiles with median velocities more blueshifted than –50 km s{sup –1}, is seen in 26 (70%) of the 37 OH-detected targets, suggesting a wide-angle (∼145°) outflow geometry. Conversely, unambiguous evidence for molecular inflows, based on the detection of OH absorption profiles with median velocities more redshifted than +50 km s{sup –1}, is seen in only four objects, suggesting a planar or filamentary geometry for the inflowing gas. Terminal outflow velocities of ∼–1000 km s{sup –1} are measured in several objects, but median outflow velocities are typically ∼–200 km s{sup –1}. While the outflow velocities show no statistically significant dependence on the star formation rate, they are distinctly more blueshifted among systems with large active galactic nucleus (AGN) fractions and luminosities [log (L{sub AGN}/L{sub ☉}) ≥ 11.8 ± 0.3]. The quasars in these systems play a dominant role in driving the molecular outflows. However, the most AGN dominated systems, where OH is seen purely in emission, show relatively modest OH line widths, despite their large AGN luminosities, perhaps indicating that molecular outflows subside once the quasar has cleared a path through the obscuring material.

  10. Discovery of extreme [O III] λ5007 Å outflows in high-redshift red quasars

    Science.gov (United States)

    Zakamska, Nadia L.; Hamann, Fred; Pâris, Isabelle; Brandt, W. N.; Greene, Jenny E.; Strauss, Michael A.; Villforth, Carolin; Wylezalek, Dominika; Alexandroff, Rachael M.; Ross, Nicholas P.

    2016-07-01

    Black hole feedback is now a standard component of galaxy formation models. These models predict that the impact of black hole activity on its host galaxy likely peaked at z = 2-3, the epoch of strongest star formation activity and black hole accretion activity in the Universe. We used XSHOOTER on the Very Large Telescope to measure rest-frame optical spectra of four z ˜ 2.5 extremely red quasars with infrared luminosities ˜1047 erg s-1. We present the discovery of very broad (full width at half max = 2600-5000 km s-1), strongly blueshifted (by up to 1500 km s-1) [O III] λ5007 Å emission lines in these objects. In a large sample of type 2 and red quasars, [O III] kinematics are positively correlated with infrared luminosity, and the four objects in our sample are on the extreme end in both [O III] kinematics and infrared luminosity. We estimate that at least 3 per cent of the bolometric luminosity in these objects is being converted into the kinetic power of the observed wind. Photo-ionization estimates suggest that the [O III] emission might be extended on a few kpc scales, which would suggest that the extreme outflow is affecting the entire host galaxy of the quasar. These sources may be the signposts of the most extreme form of quasar feedback at the peak epoch of galaxy formation, and may represent an active `blow-out' phase of quasar evolution.

  11. Quasar-driven outflows account for the missing extragalactic gamma-ray background

    CERN Document Server

    Wang, Xiawei

    2016-01-01

    The origin of the extragalactic $\\gamma$-ray background permeating throughout the Universe remains a mystery forty years after its discovery. The extrapolated population of blazars can account for only half of the background radiation at the energy range of ~ 0.1-10 GeV. Here we show that quasar-driven outflows generate relativistic protons that produce the missing component of the extragalactic $\\gamma$-ray background and naturally match its spectral fingerprint, with a generic break above ~ 1 GeV. The associated $\\gamma$-ray sources are too faint to be detected individually, explaining why they had not been identified so far. However, future radio observations may image their shock fronts directly. Our best fit to the Fermi-LAT observations of extragalactic $\\gamma$-ray background spectrum provides constraints on the outflow parameters that agree with observations of these outflows and theoretical predictions.

  12. Extreme-Velocity Quasar Outflows and the Role of X-ray Shielding

    CERN Document Server

    Hamann, Fred; McGraw, Sean; Hidalgo, Paola Rodriguez; Shields, Joseph; Capellupo, Daniel; Charlton, Jane; Eracleous, Michael

    2013-01-01

    Quasar accretion disk winds observed via broad absorption lines (BALs) in the UV produce strong continuous absorption in X-rays. The X-ray absorber is believed to serve critically as a radiative shield to enable radiative driving. However, "mini-BAL" and narrow absorption line outflows have dramatically less X-ray absorption than BALs. Here we examine X-ray and rest-frame UV spectra of 8 mini-BAL quasars with outflow speeds in the range 0.1c to 0.2c to test whether extreme speeds require a strong shield. We find that the X-ray absorption is weak or moderate, with neutral-equivalent column densities N_H ~ 8 x 10^15 cm (based on measured line depths), the outflows have shapes like thin "pancakes" viewed face-on, or they occupy larger volumes like a spray of many dense clouds with a small volume filling factor. These results favor models with magnetic confinement in magnetic disk winds.

  13. Fast outflows in broad absorption line quasars and their connection with CSS/GPS sources

    CERN Document Server

    Bruni, G; Montenegro-Montes, F M; Brienza, M; González-Serrano, J I

    2015-01-01

    Broad absorption line quasars are among the objects presenting the fastest outflows. The launching mechanism itself is not completely understood. Models in which they could be launched from the accretion disk, and then curved and accelerated by the effect of the radiation pressure, have been presented. We conducted an extensive observational campaign, from radio to optical band, to collect information about their nature and test the models present in the literature, the main dichotomy being between a young scenario and an orientation one. We found a variety of possible orientations, morphologies, and radio ages, not converging to a particular explanation for the BAL phenomenon. From our latest observations in the m- and mm-band, we obtained an indication of a lower dust abundance with respect to normal quasars, thus suggesting a possible feedback process on the host galaxy. Also, in the low-frequency regime we confirmed the presence of CSS components, sometime in conjunction with a GPS one already detected at...

  14. Outflows Driven by Quasars in High-Redshift Galaxies with Radiation Hydrodynamics

    Science.gov (United States)

    Bieri, Rebekka; Dubois, Yohan; Rosdahl, Joakim; Wagner, Alexander; Silk, Joseph; Mamon, Gary A.

    2016-09-01

    The quasar mode of Active Galactic Nuclei (AGN) in the high-redshift Universe is routinely observed in gas-rich galaxies together with large-scale AGN-driven winds. It is crucial to understand how photons emitted by the central AGN source couple to the ambient interstellar-medium to trigger large-scale outflows. By means of radiation-hydrodynamical simulations of idealised galactic discs, we study the coupling of photons with the multiphase galactic gas, and how it varies with gas cloud sizes, and the radiation bands included in the simulations, which are ultraviolet (UV), optical, and infrared (IR). We show how a quasar with a luminosity of 146 erg s-1 can drive large-scale winds with velocities of 102 - 103 km s-1 and mass outflow rates around 10^3 M_⊙ yr^{-1} for times of order a few million years. Infrared radiation is necessary to efficiently transfer momentum to the gas via multi-scattering on dust in dense clouds. However, IR multi-scattering, despite being extremely important at early times, quickly declines as the central gas cloud expands and breaks up, allowing the radiation to escape through low gas density channels. The typical number of multi-scattering events for an IR photon is only about a quarter of the mean optical depth from the center of the cloud. Our models account for the observed outflow rates of ˜ 500-1000 M_{⊙} {yr}^{-1} and high velocities of ˜ 10^3 km s^{-1}, favouring winds that are energy-driven via extremely fast nuclear outflows, interpreted here as being IR-radiatively-driven winds.

  15. Outflows Driven by Quasars in High-Redshift Galaxies with Radiation Hydrodynamics

    CERN Document Server

    Bieri, Rebekka; Rosdahl, Joakim; Wagner, Alexander Y; Silk, Joseph; Mamon, Gary A

    2016-01-01

    The quasar mode of Active Galactic Nuclei (AGN) in the high-redshift Universe is routinely observed in gas-rich galaxies together with large-scale AGN-driven winds. It is crucial to understand how photons emitted by the central AGN source couple to the ambient interstellar-medium to trigger large-scale outflows. By means of radiation-hydrodynamical simulations of idealised galactic discs, we study the coupling of photons with the multiphase galactic gas, and how it varies with gas cloud sizes, and the radiation bands included in the simulations, which are ultraviolet (UV), optical, and infrared (IR). We show how a quasar with a luminosity of $10^{46}$ erg/s can drive large-scale winds with velocities of $10^2-10^3$ km/s and mass outflow rates around $10^3$ M$_\\odot$/yr for times of order a few million years. Infrared radiation is necessary to efficiently transfer momentum to the gas via multi-scattering on dust in dense clouds. However, IR multi-scattering, despite being extremely important at early times, qu...

  16. Constraining the dynamical importance of hot gas and radiation pressure in quasar outflows using emission line ratios

    CERN Document Server

    Stern, Jonathan; Zakamska, Nadia L; Hennawi, Joseph F

    2015-01-01

    Quasar feedback models often predict an expanding hot gas bubble which drives a galaxy-scale outflow. In many circumstances the hot gas is predicted to radiate inefficiently, making the hot bubble hard to observe directly. We present an indirect method to detect the presence of a hot bubble using hydrostatic photoionization models of the cold (10^4 K) line-emitting gas. These models assume that the cold gas is in pressure equilibrium with either the hot gas pressure or with the radiation pressure, whichever is larger. We compare our models with observations of the broad line region (BLR), the inner face of the dusty torus, the narrow line region (NLR), and the extended NLR, and thus constrain the hot gas pressure over a dynamical range of 10^5 in radius, from 0.1 pc to 10 kpc. We find that the emission line ratios observed in the average quasar spectrum are consistent with radiation-pressure-dominated models on all scales. On scales > L_AGN/c inferred for galaxy-scale outflows in luminous quasars. This appare...

  17. IDENTIFICATION OF OUTFLOWS AND CANDIDATE DUAL ACTIVE GALACTIC NUCLEI IN SDSS QUASARS AT z = 0.8-1.6

    Energy Technology Data Exchange (ETDEWEB)

    Barrows, R. Scott; Lacy, Claud H. Sandberg; Kennefick, Julia; Kennefick, Daniel; Berrier, Joel C. [Arkansas Center for Space and Planetary Sciences, University of Arkansas, Fayetteville, AR 72701 (United States); Comerford, Julia M., E-mail: rbarrows@uark.edu [Astronomy Department, University of Texas at Austin, Austin, TX 78712 (United States)

    2013-06-01

    We present a sample of 131 quasars from the Sloan Digital Sky Survey at redshifts 0.8 < z < 1.6 with double peaks in either of the high-ionization narrow emission lines [Ne V] {lambda}3426 or [Ne III] {lambda}3869. These sources were selected with the intention of identifying high-redshift analogs of the z < 0.8 active galactic nuclei (AGNs) with double-peaked [O III] {lambda}5007 lines, which might represent AGN outflows or dual AGNs. Lines of high ionization potential are believed to originate in the inner, highly photoionized portion of the narrow line region, and we exploit this assumption to investigate the possible kinematic origins of the double-peaked lines. For comparison, we measure the [Ne V] {lambda}3426 and [Ne III] {lambda}3869 double peaks in low-redshift (z < 0.8) [O III]-selected sources. We find that [Ne V] {lambda}3426 and [Ne III] {lambda}3869 show a correlation between line splitting and line width similar to that of [O III] {lambda}5007 in other studies, and the velocity splittings are correlated with the quasar Eddington ratio. These results suggest an outflow origin for at least a subset of the double peaks, allowing us to study the high-ionization gas kinematics around quasars. However, we find that a non-negligible fraction of our sample show no evidence for an ionization stratification. For these sources, the outflow scenario is less compelling, leaving the dual AGN scenario as a viable possibility. Finally, we find that our sample shows an anti-correlation between the velocity-offset ratio and luminosity ratio of the components, which is a potential dynamical argument for the presence of dual AGNs. Therefore, this study serves as a first attempt at extending the selection of candidate dual AGNs to higher redshifts.

  18. RESOLVING THE CLUMPY STRUCTURE OF THE OUTFLOW WINDS IN THE GRAVITATIONALLY LENSED QUASAR SDSS J1029+2623

    Energy Technology Data Exchange (ETDEWEB)

    Misawa, Toru [School of General Education, Shinshu University, 3-1-1 Asahi, Matsumoto, Nagano 390-8621 (Japan); Inada, Naohisa [Department of Physics, Nara National College of Technology, Yamatokohriyama, Nara 639-1080 (Japan); Oguri, Masamune [Research Center for the Early Universe, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Gandhi, Poshak [Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom); Horiuchi, Takashi; Koyamada, Suzuka; Okamoto, Rina, E-mail: misawatr@shinshu-u.ac.jp [Department of Physics, Faculty of Science, Shinshu University, 3-1-1 Asahi, Matsumoto, Nagano 390-8621 (Japan)

    2014-10-20

    We study the geometry and the internal structure of the outflowing wind from the accretion disk of a quasar by observing multiple sightlines with the aid of strong gravitational lensing. Using Subaru/High Dispersion Spectrograph, we performed high-resolution (R ∼ 36,000) spectroscopic observations of images A and B of the gravitationally lensed quasar SDSS J1029+2623 (at z {sub em} ∼ 2.197) whose image separation angle, θ ∼ 22.''5, is the largest among those discovered so far. We confirm that the difference in absorption profiles in images A and B discovered by Misawa et al. has remained unchanged since 2010, implying the difference is not due to time variability of the absorption profiles over the delay between the images, Δt ∼ 744 days, but rather due to differences along the sightlines. We also discovered a time variation of C IV absorption strength in both images A and B due to a change in the ionization condition. If a typical absorber's size is smaller than its distance from the flux source by more than five orders of magnitude, it should be possible to detect sightline variations among images of other smaller separation, galaxy-scale gravitationally lensed quasars.

  19. Broad Absorption Line Quasars with Redshifted Troughs: High-Velocity Infall or Rotationally Dominated Outflows?

    CERN Document Server

    Hall, Patrick B; Petitjean, P; Paris, I; Ak, N Filiz; Shen, Yue; Gibson, R R; Aubourg, E; Anderson, S F; Schneider, D P; Bizyaev, D; Brinkmann, J; Malanushenko, E; Malanushenko, V; Myers, A D; Oravetz, D J; Ross, N P; Shelden, A; Simmons, A E; Streblyanska, A; Weaver, B A; York, D G

    2013-01-01

    We report the discovery in the Sloan Digital Sky Survey and the SDSS-III Baryon Oscillation Spectroscopic Survey of seventeen broad absorption line (BAL) quasars with high-ionization troughs that include absorption redshifted relative to the quasar rest frame. The redshifted troughs extend to velocities up to v=12,000 km/s and the trough widths exceed 3000 km/s in all but one case. Approximately 1 in 1000 BAL quasars with blueshifted C IV absorption also has redshifted C IV absorption; objects with C IV absorption present only at redshifted velocities are roughly four times rarer. In more than half of our objects, redshifted absorption is seen in C II or Al III as well as C IV, making low-ionization absorption at least ten times more common among BAL quasars with redshifted troughs than among standard BAL quasars. However, the C IV absorption equivalent widths in our objects are on average smaller than those of standard BAL quasars with low-ionization absorption. We consider several possible ways of generatin...

  20. NuSTAR Reveals Relativistic Reflection but no Ultra-fast Outflow in the Quasar PG1211+143

    DEFF Research Database (Denmark)

    Zoghbi, A.; Miller, J. M.; Walton, D. J.

    2015-01-01

    We report on four epochs of observations of the quasar PG 1211+143 using NuSTAR. The net exposure time is 300 ks. Prior work on this source found suggestive evidence of an ultra-fast outflow ( UFO) in the Fe K band with a velocity of approximately 0.1c. The putative flow would carry away a high-m...

  1. The link between quasar broad-line region and galaxy-scale outflows and accurate CIV-based black hole masses

    Science.gov (United States)

    Coatman, Liam; Hewett, Paul C.; Banerji, Manda; Richards, Gordon T.; Hennawi, Joseph F.; Prochaska, Jason X.

    2017-01-01

    Accurate black-hole (BH) mass estimates for high-redshift (z>2) quasars are essential for better understanding the relationship between super-massive BH accretion and star formation. Progress is currently limited by the large systematic errors in virial BH-masses derived from the CIV broad emission line, which is often significantly blueshifted relative to systemic, most likely due to outflowing gas in the quasar broad-line region. We have assembled Balmer-line based BH masses for a large sample of 230 high-luminosity (1045.5-1048 ergs-1), redshift 1.5blueshifts seen in the quasar population. We find the CIV-based BH-masses to be larger than the corresponding Balmer line-based masses by almost an order of magnitude at the most extreme blueshifts (˜5000 kms-1). An empirical correction to the CIV BH-masses is derived, which depends only on the properties of the CIV line itself (i.e. blueshift and FWHM). We show that this new correction now enables the derivation of un-biased CIV-based virial BH masses for the majority of high-luminosity, high-redshift quasars.In the same high-luminosity quasar sample, we find the narrow [OIII] emission to be weaker and more asymmetric than is generally found in lower-luminosity AGN and that a significant fraction of our quasars have exceptionally broad (FWHM > 3000 kms-1), blueshifted [OIII] emission. We find a strong correlation between the CIV and [OIII] blueshifts. This correlation holds even for quasars at fixed luminosity and suggests that broad line region outflows in quasars are connected to galaxy-scale winds.

  2. NuSTAR Reveals Relativistic Reflection But No Ultra-Fast Outflow in the Quasar Pg∼1211+143

    Science.gov (United States)

    Zoghbi, A.; Miller, J. M.; Walton, D. J.; Harrison, F. A.; Fabian, A. C.; Reynolds, C. S.; Boggs, S. E.; Christensen, F. E.; Craig, W.; Hailey, C. J.; Stern, D.; Zhang, W. W.

    2015-01-01

    We report on four epochs of observations of the quasar PG 1211+143 using NuSTAR. The net exposure time is 300 ks. Prior work on this source found suggestive evidence of an ultra-fast outflow (UFO) in the Fe K band with a velocity of approximately 0.1c. The putative flow would carry away a high-mass flux and kinetic power, with broad implications for feedback and black hole--galaxy co-evolution. NuSTAR detects PG 1211+143 out to 30 keV, meaning that the continuum is well-defined both through and above the Fe K band. A characteristic relativistic disk reflection spectrum is clearly revealed via a broad Fe K emission line and Compton back-scattering curvature. The data offer only weak constraints on the spin of the black hole. A careful search for UFOs shows no significant absorption feature above 90% confidence. The limits are particularly tight when relativistic reflection is included. We discuss the statistics and the implications of these results in terms of connections between accretion onto quasars, Seyferts, and stellar-mass black holes, and feedback into their host environments.

  3. NuSTAR REVEALS RELATIVISTIC REFLECTION BUT NO ULTRA-FAST OUTFLOW IN THE QUASAR PG 1211+143

    Energy Technology Data Exchange (ETDEWEB)

    Zoghbi, A.; Miller, J. M. [Department of Astronomy, University of Michigan, 1085 South University Avenue, Ann Arbor, MI 48109 (United States); Walton, D. J.; Stern, D. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Harrison, F. A. [Space Radiation Laboratory, California Institute of Technology, Pasadena, CA 91125 (United States); Fabian, A. C. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB3 OHA (United Kingdom); Reynolds, C. S. [Department of Astronomy, University of Maryland, College Park, MD 20742-2421 (United States); Boggs, S. E.; Craig, W. [Space Science Laboratory, University of California, Berkeley, CA 94720 (United States); Christensen, F. E. [DTU Space. National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark); Hailey, C. J. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Zhang, W. W., E-mail: abzoghbi@umich.edu [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2015-02-01

    We report on four epochs of observations of the quasar PG 1211+143 using NuSTAR. The net exposure time is 300 ks. Prior work on this source found suggestive evidence of an ultra-fast outflow (UFO) in the Fe K band with a velocity of approximately 0.1c. The putative flow would carry away a high-mass flux and kinetic power, with broad implications for feedback and black hole--galaxy co-evolution. NuSTAR detects PG 1211+143 out to 30 keV, meaning that the continuum is well-defined both through and above the Fe K band. A characteristic relativistic disk reflection spectrum is clearly revealed via a broad Fe K emission line and Compton back-scattering curvature. The data offer only weak constraints on the spin of the black hole. A careful search for UFOs shows no significant absorption feature above 90% confidence. The limits are particularly tight when relativistic reflection is included. We discuss the statistics and the implications of these results in terms of connections between accretion onto quasars, Seyferts, and stellar-mass black holes, and feedback into their host environments.

  4. Identification of Outflows and Candidate Dual Active Galactic Nuclei in SDSS Quasars at z=0.8-1.6

    CERN Document Server

    Barrows, R Scott; Kennefick, Julia; Comerford, Julia M; Kennefick, Daniel; Berrier, Joel C

    2013-01-01

    We present a sample of 131 quasars from the Sloan Digital Sky Survey at redshifts 0.8outflows or dual AGN. Lines of high-ionization potential are believed to originate in the inner, highly photoionized portion of the narrow line region (NLR), and we exploit this assumption to investigate the possible kinematic origins of the double-peaked lines. For comparison, we measure the [NeV]3426 and [NeIII]3869 double peaks in low-redshift (z<0.8) [OIII]-selected sources. We find that [NeV]3426 and [NeIII]3869 show a correlation between line-splitting and line-width similar to that of [OIII]5007 in other studies; and the velocity-splittings are correlated with the quasar Eddington ratio. These results suggest an outfl...

  5. NuSTAR Reveals Relativistic Reflection But No Ultra-Fast Outflow In The Quasar PG 1211+143

    CERN Document Server

    Zoghbi, A; Walton, D J; Harrison, F A; Fabian, A C; Reynolds, C S; Boggs, S E; Christensen, F E; Craig, W; Hailey, C J; Stern, D; Zhang, W W

    2015-01-01

    We report on four epochs of observations of the quasar PG 1211+143 using NuSTAR. The net exposure time is 300 ks. Prior work on this source found suggestive evidence of an 'ultra-fast outflow' (or, UFO) in the Fe K band, with a velocity of approximately 0.1c. The putative flow would carry away a high mass flux and kinetic power, with broad implications for feedback and black hole-galaxy co-evolution. NuSTAR detects PG 1211+143 out to 30 keV, meaning that the continuum is well-defined both through and above the Fe K band. A characteristic relativistic disk reflection spectrum is clearly revealed, via a broad Fe K emission line and Compton back-scattering curvature. The data offer only weak constraints on the spin of the black hole. A careful search for UFO's show no significant absorption feature above 90% confidence. The limits are particularly tight when relativistic reflection is included. We discuss the statistics and the implications of these results in terms of connections between accretion onto quasars,...

  6. Resolving the Clumpy Structure of the Outflow Winds in the Gravitationally Lensed Quasar SDSS J1029+2623

    CERN Document Server

    Misawa, Toru; Oguri, Masamune; Gandhi, Poshak; Horiuchi, Takashi; Koyamada, Suzuka; Okamoto, Rina

    2014-01-01

    We study the geometry and the internal structure of the outflowing wind from the accretion disk of a quasar by observing multiple sightlines with the aid of strong gravitational lensing. Using Subaru/HDS, we performed high-resolution ($R$ $\\sim$ 36,000) spectroscopic observations of images A and B of the gravitationally lensed quasar SDSS J1029+2623 (at $z_{em}$ $\\sim$ 2.197) whose image separation angle, $\\theta$ $\\sim$ 22$^{\\prime\\prime}\\!\\!$.5, is the largest among those discovered so far. We confirm that the difference in absorption profiles in the images A and B discovered by Misawa et al. (2013) remains unchanged since 2010, implying the difference is not due to time variability of the absorption profiles over the delay between the images, $\\Delta t$ $\\sim$ 744 days, but rather due to differences along the sightlines. We also discovered time variation of C IV absorption strength in both images A and B, due to change of ionization condition. If a typical absorber's size is smaller than its distance from ...

  7. Discovery of extreme [OIII]5007A outflows in high-redshift red quasars

    CERN Document Server

    Zakamska, Nadia L; Pâris, Isabelle; Brandt, W N; Greene, Jenny E; Strauss, Michael A; Villforth, Carolin; Wylezalek, Dominika; Alexandroff, Rachael M; Ross, Nicholas P

    2015-01-01

    Black hole feedback is now a standard component of galaxy formation models. These models predict that the impact of black hole activity on its host galaxy likely peaked at z=2-3, the epoch of strongest star formation activity and black hole accretion activity in the Universe. We used XShooter on the Very Large Telescope to measure rest-frame optical spectra of four z~2.5 extremely red quasars with infrared luminosities ~10^47 erg/sec. We present the discovery of very broad (full width at half max= 2600-5000 km/sec), strongly blue-shifted (by up to 1500 km/sec) [OIII]5007A emission lines in these objects. In a large sample of obscured and red quasars, [OIII] kinematics are positively correlated with infrared luminosity, and the four objects in our sample are on the extreme end both in [OIII] kinematics and infrared luminosity. We estimate that ~3% of the bolometric luminosity in these objects is being converted into the kinetic power of the observed wind. These sources may be the signposts of the most extreme ...

  8. Ultraviolet and Optical Emission Line Outflows in the Heavily Obscured Quasar SDSS J000610.67+121501.2: At the Scale of the Dusty Torus and Beyond

    Science.gov (United States)

    Zhang, Shaohua; Zhou, Hongyan; Shi, Xiheng; Pan, Xiang; Wang, Ji; Jiang, Ning; Ji, Tuo; Jiang, Peng; Liu, Wenjuan; Wang, Huiyuan

    2017-02-01

    Broad emission line outflows of active galactic nuclei have been proposed for many years but are very difficult to quantitatively study because of the coexistence of the gravitationally bound and outflow emission. We present detailed analysis of a heavily reddened quasar, SDSS J000610.67+121501.2, whose normal ultraviolet broad emission lines (BELs) are heavily suppressed by the dusty torus as a natural “coronagraph,” and thus the blueshifted BELs (BBELs) can be reliably measured. The physical properties of the emission-line outflows are derived as follows: ionization parameter U∼ {10}-0.5, column density {N}{{H}}∼ {10}22.0 cm‑2, covering fraction of ∼0.1, and upper limit density of {n}{{H}}∼ {10}5.8 cm‑3. The outflow gases are located at least 41 pc away from the central engine, which suggests that they have expanded to the scale of the dust torus or beyond. Besides, Lyα shows a narrow symmetric component, to our surprise, which is undetected in any other lines. After inspecting the narrow emission line region and the star-forming region as the origin of the Lyα narrow line, we propose that the end result of outflows, diffusing gases in the larger region, acts as the screen of Lyα photons. Future high spatial resolution spectrometry and/or spectropolarimetric observations are needed to make a final clarification.

  9. SDSS J163459.82+204936.0: A Ringed Infrared-Luminous Quasar with Outflows in both Absorption and Emission Lines

    CERN Document Server

    Liu, Wen-Juan; Jiang, Ning; Wu, Xufen; Lyu, Jianwei; Shi, Xiheng; Shu, Xinwen; Jiang, Peng; Ji, Tuo; Wang, Jiang-Guo; Wang, Shu-Fen; Sun, Luming

    2016-01-01

    SDSS J1634+2049 is a local (z = 0.1293) infrared-luminous quasar with LIR= 10^11.91 Lsun. We present a detailed multiwavelength study of both the host galaxy and the nucleus. The host galaxy demonstrates violent, obscured star formation activities with SFR ~ 140 Msun yr^-1, estimated from either the PAH emission or IR luminosity. The optical to NIR spectra exhibit a blueshifted narrow cuspy component in Hb, HeI5876,10830 and other emission lines consistently with an offset velocity of ~900 km/s, as well as additional blueshifting phenomena in high-ionization lines , while there exist blueshifted broad absorption lines (BALs) in NaID and HeI*3889,10830, indicative of the AGN outflows producing BALs and emission lines. Constrained mutually by the several BALs with CLOUDY, the physical properties of the absorption-line outflow are derived as follows: 10^4 < n_H <= 10^5 cm^-3, 10^-1.3 <= U <= 10^-0.7 and 10^22.5<= N_H <= 10^22.9 cm^-2 , similar to those derived for the emission-line outflows. Th...

  10. The Complete Ultraviolet Spectrum of the Archetypal "Wind-dominated" Quasar Mrk 231: Absorption and Emission from a High-speed Dusty Nuclear Outflow

    Science.gov (United States)

    Veilleux, S.; Meléndez, M.; Tripp, T. M.; Hamann, F.; Rupke, D. S. N.

    2016-07-01

    New near- and far-ultraviolet (NUV and FUV) Hubble Space Telescope spectra of Mrk 231, the nearest quasar known, are combined with ground-based optical spectra to study the remarkable dichotomy between the FUV and NUV-optical spectral regions in this object. The FUV emission-line features are faint, broad, and highly blueshifted (up to ˜7000 km s-1), with no significant accompanying absorption. In contrast, the profiles of the NUV absorption features resemble those of the optical Na i D, He i, and Ca ii H and K lines, exhibiting broad blueshifted troughs that overlap in velocity space with the FUV emission-line features and indicate a dusty, high-density and patchy broad absorption line (BAL) screen covering ˜90% of the observed continuum source at a distance ≲2-20 pc. The FUV continuum emission does not show the presence of any obvious stellar features and is remarkably flat compared with the steeply declining NUV continuum. The NUV (FUV) features and continuum emission have not varied significantly over the past ˜22 (3) years and are unresolved on scales ˜40 (170) pc. These results favor an active galactic nucleus origin for the NUV-FUV line and continuum emission. The observed FUV line emission is produced in the outflowing BAL cloud system, while the Balmer lines arise primarily from the standard broad line region seen through the dusty BAL screen. Our data are inconsistent with the recently proposed binary black hole model. We argue instead that Mrk 231 is the nearest example of weak-lined “wind-dominated” quasars with high Eddington ratios and geometrically thick (“slim”) accretion disks; these quasars are likely more common in the early universe.

  11. The XMM deep survey in the CDF-S. IX. An X-ray outflow in a luminous obscured quasar at z~1.6

    CERN Document Server

    Vignali, C; Comastri, A; Gilli, R; Lanzuisi, G; Ranalli, P; Cappelluti, N; Mainieri, V; Georgantopoulos, I; Carrera, F J; Fritz, J; Brusa, M; Brandt, W N; Bauer, F E; Fiore, F; Tombesi, F

    2015-01-01

    In active galactic nuclei (AGN)-galaxy co-evolution models, AGN winds and outflows are often invoked to explain why super-massive black holes and galaxies stop growing efficiently at a certain phase of their lives. They are commonly referred to as the leading actors of feedback processes. Evidence of ultra-fast (v>0.05c) outflows in the innermost regions of AGN has been collected in the past decade by sensitive X-ray observations for sizable samples of AGN, mostly at low redshift. Here we present ultra-deep XMM-Newton and Chandra spectral data of an obscured (Nh~2x10^{23} cm^-2), intrinsically luminous (L2-10keV~4x10^{44} erg/s) quasar (named PID352) at z~1.6 (derived from the X-ray spectral analysis) in the Chandra Deep Field-South. The source is characterized by an iron emission and absorption line complex at observed energies of E~2-3 keV. While the emission line is interpreted as being due to neutral iron (consistent with the presence of cold absorption), the absorption feature is due to highly ionized ir...

  12. The Contribution of Host Galaxies to the Infrared Energy Output of z ≳ 5.0 Quasars

    Science.gov (United States)

    Lyu, Jianwei; Rieke, G. H.; Alberts, Stacey

    2016-01-01

    The infrared spectral energy distributions of z ≳ 5 quasars can be reproduced by combining a low-metallicity galaxy template with a standard active galactic nucleus (AGN) template. The host galaxy is represented by Haro 11, a compact, moderately low metallicity, starbursting galaxy that shares typical features of high-z galaxies. For the vast majority of z ≳ 5 quasars, the AGN contribution is well modeled by a standard empirical template with the contamination of star formation in the infrared subtracted. Together, these two templates can separate the contributions from the host galaxy and the AGN even in the case of limited data points, given that this model has only two free parameters. Using this method, we reanalyze 69 z ≳ 5 quasars with extensive Herschel observations and derive their AGN luminosities [LAGN = (0.78{--}27.4)× {10}13 {L}⊙ ], infrared luminosities from star formation [{L}{{SF,IR}}\\quad ≲ (1.5{--}25.7)× {10}12 {L}⊙ ], and corresponding star formation rates ({{SFR}}\\quad ≲ 290{--}2650{M}⊙ {{{yr}}}-1). The average infrared luminosity from star formation and the average total AGN luminosity of the z ≳ 5 quasar sample follow the correlation defined by quasars at z ˜ (3{--}5)× {10}11{M}⊙ . Combining with the black hole (BH) mass measurements, this stellar mass is adequate to establish a BH-galaxy mass ratio {M}{{BH}}/{M}* at 0.1%-1%, consistent with the local relation.

  13. Cosmic reionization of hydrogen and helium: contribution from both mini-quasars and stars

    CERN Document Server

    Hao, Jing-Meng; Wang, Lei

    2015-01-01

    Observations on the high-redshift galaxies at $z>6$ imply that their ionizing emissivity is unable to fully reionize the Universe at $z\\sim 6$. Either a high escape fraction of ionizing photons from these galaxies or a large population of faint galaxies below the detection limit are required. However, these requirements are somewhat in tension with present observations. In this work, we explored the combined contribution of mini-quasars and stars to the reionization of cosmic hydrogen and helium. Our model is roughly consistent with: (1) the low escape fractions of ionizing photons from the observed galaxies, (2) the optical depth of Cosmic Microwave Background (CMB) measured by the WMAP-7, and (3) the redshift of the end of hydrogen and helium reionization at $z\\approx 6$ and $z\\approx 3$, respectively. Neither an extremely high escape fraction nor a large population of fainter galaxies is required in this scenario. In our most optimistic model, more than $\\sim20\\%$ of the cosmic helium is reionized by $z\\si...

  14. The Contribution of Host Galaxies to the Infrared Energy Output of $z\\gtrsim5.0$ QUASARS

    CERN Document Server

    Lyu, Jianwei; Alberts, Stacey

    2015-01-01

    The infrared spectral energy distributions (SEDs) of $z\\gtrsim 5$ quasars can be reproduced by combining a low-metallicity galaxy template with a standard AGN template. The host galaxy is represented by Haro 11, a compact, moderately low metallicity, star-bursting galaxy that shares typical features of high-$z$ galaxies. For the vast majority of $z\\gtrsim 5$ quasars, the AGN contribution is well modeled by a standard empirical template with the contamination of star formation in the infrared subtracted. Together, these two templates can separate the contributions from the host galaxy and the AGN even in the case of limited data points, given that this model has only two free parameters. Using this method, we re-analyze 69 $z\\gtrsim 5$ quasars with extensive Herschel observations, and derive their AGN luminosities $L_{\\rm AGN}$ in a range $\\sim (0.78-27.4) \\times10^{13}\\, L_{\\odot}$, the infrared luminosities from star formation $L_{\\rm SF,IR} \\sim (<1.5-25.7)\\times10^{12}\\, L_{\\odot}$, and the correspondin...

  15. Minor Contribution of Quasars to Ionizing Photon Budget at z ∼ 6: Update on Quasar Luminosity Function at the Faint End with Subaru/Suprime-Cam

    Science.gov (United States)

    Onoue, Masafusa; Kashikawa, Nobunari; Willott, Chris J.; Hibon, Pascale; Im, Myungshin; Furusawa, Hisanori; Harikane, Yuichi; Imanishi, Masatoshi; Ishikawa, Shogo; Kikuta, Satoshi; Matsuoka, Yoshiki; Nagao, Tohru; Niino, Yuu; Ono, Yoshiaki; Ouchi, Masami; Tanaka, Masayuki; Tang, Ji-Jia; Toshikawa, Jun; Uchiyama, Hisakazu

    2017-10-01

    We constrain the quasar contribution to the cosmic reionization based on our deep optical survey of z ∼ 6 quasars down to z R = 24.15 using Subaru/Suprime-Cam in three UKIDSS-DXS fields covering 6.5 deg2. In Kashikawa et al. (2015), we select 17 quasar candidates and report our initial discovery of two low-luminosity quasars ({M}1450∼ -23) from seven targets, one of which might be a Lyα-emitting galaxy. From an additional optical spectroscopy, none of the four candidates out of the remaining 10 turn out to be genuine quasars. Moreover, the deeper optical photometry provided by the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) shows that, unlike the two already-known quasars, the i ‑ z and z ‑ y colors of the last six candidates are consistent with M- or L-type brown dwarfs. Therefore, the quasar luminosity function (QLF) measurement in the previous paper is confirmed. Compiling the QLF measurements from the literature over a wide magnitude range, including an extremely faint AGN candidate from Parsa et al. (2017), to fit them with a double power law, we find that the best-fit faint-end slope is α =-{2.04}-0.18+0.33 (-{1.98}-0.21+0.48) and characteristic magnitude is {M}1450* =-{25.8}-1.9+1.1 (-{25.7}-1.8+1.0) in the case of two (one) quasar detection. Our result suggests that, if the QLF is integrated down to {M}1450=-18, quasars produce ∼1%–12% of the ionizing photons required to fully ionize the universe at z ∼ 6 with a 2σ confidence level, assuming that the escape fraction is {f}{esc}=1 and the intergalactic medium clumpy factor is C = 3. Even when the systematic uncertainties are taken into account, our result supports the scenario that quasars are the minor contributors of the reionization.

  16. Physical properties of galactic winds using background quasars

    CERN Document Server

    Bouche, N; Vargas, R; Kacprzak, G G; Martin, C L; Cooke, J; Churchill, C W

    2011-01-01

    We investigate the spatial location of quasar lines-of-sight with strong MgII absorption (with EW>0.3 AA) passing near spectroscopically identified galaxies at z~0.1. Using a dozen quasar-galaxy pairs available from the literature, we find that the azimuthal orientation of the quasar sight-lines is bi-modal, with about half the MgII sight-lines aligned with the major axis and the other half within $\\alpha=$30 degree of the minor axis. This dichotomy is also present in the instantaneous star-formation rates (SFRs) of the host. These results indicate that both gaseous disks and strong bipolar outflows contribute to MgII cross-section. In addition, a simple bi-conical wind model is able to reproduce the observed MgII kinematics for the sight-lines aligned with the minor axis, showing that bipolar outflows contribute significantly to the MgII cross-section. Finally, using our kinematic wind model, we can extract directly key wind properties such as the de-projected outflow speed $V_{out}$ of the material traced b...

  17. The X-ray Spectrum and Spectral Energy Distribution of FIRST J155633.8+351758: a LoBAL Quasar with a Probable Polar Outflow

    CERN Document Server

    Berrington, Robert C; Gallagher, Sarah C; Ganguly, Rajib; Shang, Zhaohui; DiPompeo, Michael; Chatterjee, Ritaban; Lacy, Mark; Gregg, Michael D; Hall, Patrick B; Laurent-Muehleisen, S A

    2013-01-01

    We report the results of a new 60 ks Chandra X-ray Observatory Advanced CCD Imaging Spectrometer S-array (ACIS-S) observation of the reddened, radio-selected, highly polarized `FeLoBAL' quasar FIRST J1556+3517. We investigated a number of models of varied sophistication to fit the 531-photon spectrum. These models ranged from simple power laws to power laws absorbed by hydrogen gas in differing ionization states and degrees of partial covering. Preferred fits indicate that the intrinsic X-ray flux is consistent with that expected for quasars of similarly high luminosity, i.e., an intrinsic, dereddened and unabsorbed optical to X-ray spectral index of -1.7. We cannot tightly constrain the intrinsic X-ray power-law slope, but find indications that it is flat (photon index Gamma = 1.7 or flatter at a >99% confidence for a neutral hydrogen absorber model). Absorption is present, with a column density a few times 10^23 cm^-2, with both partially ionized models and partially covering neutral hydrogen models providi...

  18. The Complete Ultraviolet Spectrum of the Archetypal "Wind-Dominated" Quasar Mrk~231: Absorption and Emission from a High-Speed Dusty Nuclear Outflow

    CERN Document Server

    Veilleux, S; Tripp, T M; Hamann, F; Rupke, D S N

    2016-01-01

    New near- and far-ultraviolet (NUV and FUV) HST spectra of Mrk 231, the nearest quasar known, are combined with ground-based optical spectra to study the remarkable dichotomy between the FUV and NUV-optical spectral regions in this object. The FUV emission-line features are faint, broad, and highly blueshifted (up to ~7000 km/s), with no significant accompanying absorption. In contrast, the profiles of the NUV absorption features resemble those of the optical Na I D, He I, and Ca II H and K lines, exhibiting broad blue-shifted troughs that overlap in velocity space with the FUV emission-line features and indicate a dusty, high-density and patchy broad absorption line (BAL) screen covering ~90% of the observed continuum source at a distance less than ~2 - 20 pc. The FUV continuum emission does not show the presence of any obvious stellar features and is remarkably flat compared with the steeply declining NUV continuum. The NUV (FUV) features and continuum emission have not varied significantly over the past ~2...

  19. HST images of FeLoBAL quasars: Testing quasar-galaxy evolution models

    Science.gov (United States)

    Herbst, Hanna; Hamann, Fred; Villforth, Carolin; Caselli, Paola; Koekemoer, Anton M.; Veilleux, Sylvain

    2016-01-01

    We present preliminary results from an HST imaging study of FeLoBAL quasars, which have extremely low-ionization Broad Absorption Line (BAL) outflows and might be a young quasar population based on their red colors, large far-IR luminosities (suggesting high star formation rates), and powerful outflows. Some models of quasar - host galaxy evolution propose a triggering event, such as a merger, to fuel both a burst of star formation and the quasar/AGN activity. These models suggest young quasars are initially obscured inside the dusty starburst until a "blowout" phase, driven by the starburst or quasar outflows like FeLoBALs, ends the star formation and reveals the visibly luminous quasar. Despite the popularity of this evolution scheme, there is little observational evidence to support the role of mergers in triggering AGN or the youth of dust-reddened quasars (such as FeLoBALs) compared to normal blue quasars.Our Cycle 22 HST program is designed to test the youth of FeLoBAL quasars and the connection of FeLoBALs to mergers. We obtain WFC3/IR F160W images of 10 FeLoBAL quasars at redshift z~0.9 (covering ~8500A in the quasar rest frame). We will compare the host galaxy morphologies and merger signatures of FeLoBALs with normal blue quasars (which are older according to the evolution model) and non-AGN galaxies matched in redshift and stellar mass. If FeLoBAL quasars are indeed in a young evolutionary state, close in time to the initial merging event, they should have stronger merger features compared to blue quasars and non-AGN galaxies. Preliminary results suggest that this is not the case - FeLoBAL quasars appear to reside in faint, compact hosts with weak or absent merger signatures. We discuss the implications of these results for galaxy evolution models and other studies of dust-reddened quasar populations.

  20. Hubble Space Telescope Ultraviolet spectroscopy of 14 low-redshift quasars

    NARCIS (Netherlands)

    Ganguly, R.; Kaastra, J.S.

    2007-01-01

    We present low-resolution ultraviolet spectra of 14 low-redshift quasars observed with the Hubble Space Telescope STIS as part of a Snapshot project to understand the relationship between quasar outflows and luminosity. The quasar is radio-loud but has a steep spectral index and a lobe-dominated

  1. Dusty Quasars

    CERN Document Server

    Krawczyk, Coleman M; Gallagher, S C; Leighly, Karen M; Hewett, Paul C; Ross, Nicholas P; Hall, P B

    2014-01-01

    We explore the extinction/reddening of ~35,000 uniformly-selected quasars with 00.1 and 0.1% (1.3%) with E(B-V)>0.2. Simulations show both populations of quasars are intrinsically bluer than the mean composite, with a mean spectral index (${\\alpha}_{\\lambda}$) of -1.79 (-1.83). The emission and absorption-line properties of both samples reveal that quasars with intrinsically red continua have narrower Balmer lines and stronger ionizing spectral lines, the latter indicating a harder continuum in the extreme-UV and the former indicating either smaller BH mass or more face-on orientation.

  2. Blue outliers among intermediate redshift quasars

    CERN Document Server

    Marziani, P; Stirpe, G M; Dultzin, D; Del Olmo, A; Martínez-Carballo, M A

    2015-01-01

    [Oiii]{\\lambda}{\\lambda}4959,5007 "blue outliers" -- that are suggestive of outflows in the narrow line region of quasars -- appear to be much more common at intermediate z (high luminosity) than at low z. About 40% of quasars in a Hamburg ESO intermediate-z sample of 52 sources qualify as blue outliers (i.e., quasars with [OIII] {\\lambda}{\\lambda}4959,5007 lines showing large systematic blueshifts with respect to rest frame). We discuss major findings on what has become an intriguing field in active galactic nuclei research and stress the relevance of blue outliers to feedback and host galaxy evolution.

  3. Extremely red quasars in BOSS

    Science.gov (United States)

    Hamann, Fred; Zakamska, Nadia L.; Ross, Nicholas; Paris, Isabelle; Alexandroff, Rachael M.; Villforth, Carolin; Richards, Gordon T.; Herbst, Hanna; Brandt, W. Niel; Cook, Ben; Denney, Kelly D.; Greene, Jenny E.; Schneider, Donald P.; Strauss, Michael A.

    2017-01-01

    Red quasars are candidate young objects in an early transition stage of massive galaxy evolution. Our team recently discovered a population of extremely red quasars (ERQs) in the Baryon Oscillation Spectroscopic Survey (BOSS) that has a suite of peculiar emission-line properties including large rest equivalent widths (REWs), unusual `wingless' line profiles, large N V/Lyα, N V/C IV, Si IV/C IV and other flux ratios, and very broad and blueshifted [O III] λ5007. Here we present a new catalogue of C IV and N V emission-line data for 216 188 BOSS quasars to characterize the ERQ line properties further. We show that they depend sharply on UV-to-mid-IR colour, secondarily on REW(C IV), and not at all on luminosity or the Baldwin Effect. We identify a `core' sample of 97 ERQs with nearly uniform peculiar properties selected via i-W3 ≥ 4.6 (AB) and REW(C IV) ≥ 100 Å at redshifts 2.0-3.4. A broader search finds 235 more red quasars with similar unusual characteristics. The core ERQs have median luminosity ˜ 47.1, sky density 0.010 deg-2, surprisingly flat/blue UV spectra given their red UV-to-mid-IR colours, and common outflow signatures including BALs or BAL-like features and large C IV emission-line blueshifts. Their SEDs and line properties are inconsistent with normal quasars behind a dust reddening screen. We argue that the core ERQs are a unique obscured quasar population with extreme physical conditions related to powerful outflows across the line-forming regions. Patchy obscuration by small dusty clouds could produce the observed UV extinctions without substantial UV reddening.

  4. Correlations between different line-forming regions in quasar environments

    Science.gov (United States)

    Chen, Chen; Hamann, Fred; Lundgren, Britt

    2017-01-01

    The early stage of massive galaxy evolution can involve outflows driven by a starburst or a central quasar plus cold mode accretion (infall) adding to the mass build-up in the galaxies. We are using SDSS-BOSS DR12 database to study the nature of infall and outflows in quasar environments by examining the relationships of their narrow absorption lines (NALs) at positive and negative velocity shifts to other quasar properties such as their broad absorption line (BAL) outflows, emission line characteristics, radio-loudness, and reddening by dust. We also test for extreme high-velocity NAL outflows (with speeds 0.1-0.2c) based on relationships to low-speed NALs and quasar properties, and we perform detailed analyses of particular cases of rich multi-component NAL complexes that might result from high-speed quasar outflows shredding and dispersing interstellar clouds in the host galaxies. Our results show that low-velocity NALs and rich NAL complexes correlate strongly with BALs, suggesting a physical relationship. Infalling systems are less common in quasars with BALs, suggesting that BAL outflows can halt or disrupt gas accretion. The extreme high-velocity NALs (at 0.1-0.2c) show a weak relationship to BALs and a strong dependence on low-velocity NALs, indicating that a significant fraction of these systems is ejected from the quasars (and are *not* unrelated intervening clouds). We find no correlations between radio flux and low-velocity NALs, infalling systems, or rich complexes, which indicates that none of these features are closely tied to quasar radio properties. We analyze the relationship of the N V/C IV line strengths (a possible abundance/metallicity probe) in emission versus absorption lines and find no correlation between them.

  5. Protostellar Outflows

    Science.gov (United States)

    Bally, John

    2016-09-01

    Outflows from accreting, rotating, and magnetized systems are ubiquitous. Protostellar outflows can be observed from radio to X-ray wavelengths in the continuum and a multitude of spectral lines that probe a wide range of physical conditions, chemical phases, radial velocities, and proper motions. Wide-field visual and near-IR data, mid-IR observations from space, and aperture synthesis with centimeter- and millimeterwave interferometers are revolutionizing outflow studies. Many outflows originate in multiple systems and clusters. Although most flows are bipolar and some contain highly collimated jets, others are wide-angle winds, and a few are nearly isotropic and exhibit explosive behavior. Morphologies and velocity fields indicate variations in ejection velocity, mass-loss rate, and in some cases, flow orientation and degree of collimation. These trends indicate that stellar accretion is episodic and often occurs in a complex dynamical environment. Outflow power increases with source luminosity but decreases with evolutionary stage. The youngest outflows are small and best traced by molecules such as CO, SiO, H2O, and H2. Older outflows can grow to parsec scales and are best traced by shock-excited atoms and ions such as hydrogen-recombination lines, [Sii], and [Oii]. Outflows inject momentum and energy into their surroundings and provide an important mechanism in the self-regulation of star formation. However, momentum injection rates remain uncertain with estimates providing lower bounds.

  6. Star formation in quasar hosts and the origin of radio emission in radio-quiet quasars

    CERN Document Server

    Zakamska, Nadia L; Petric, Andreea; Dicken, Daniel; Greene, Jenny E; Heckman, Timothy M; Hickox, Ryan C; Ho, Luis C; Krolik, Julian H; Nesvadba, Nicole P H; Strauss, Michael A; Geach, James E; Oguri, Masamune; Strateva, Iskra V

    2015-01-01

    Radio emission from radio-quiet quasars may be due to star formation in the quasar host galaxy, to a jet launched by the supermassive black hole, or to relativistic particles accelerated in a wide-angle radiatively-driven outflow. In this paper we examine whether radio emission from radio-quiet quasars is a byproduct of star formation in their hosts. To this end we use infrared spectroscopy and photometry from Spitzer and Herschel to estimate or place upper limits on star formation rates in hosts of ~300 obscured and unobscured quasars at z<1. We find that low-ionization forbidden emission lines such as [NeII] and [NeIII] are likely dominated by quasar ionization and do not provide reliable star formation diagnostics in quasar hosts, while PAH emission features may be suppressed due to the destruction of PAH molecules by the quasar radiation field. While the bolometric luminosities of our sources are dominated by the quasars, the 160 micron fluxes are likely dominated by star formation, but they too should...

  7. LAMOST Quasar Survey

    CERN Document Server

    Wu, Xue-Bing

    2011-01-01

    The main objective of the Chinese LAMOST spectroscopic quasar survey is to discover 0.4 million new quasars from 1 million quasar candidates brighter than the magnitude limit i=20.5 in the next 5 years. This will hopefully provide the largest quasar sample for the further studies of AGN physics and cosmology. The improved quasar selection criteria based on the UKIDSS near-IR and SDSS optical colors are presented, and their advantages in uncovering the missing quasars in the quasar 'redshift desert' are demonstrated. In addition, some recent discoveries of new quasars during the LAMOST commissioning phase are presented.

  8. Decoding quasars: gravitationally redshifted spectral lines !

    CERN Document Server

    Kantharia, Nimisha G

    2016-01-01

    Further investigation of data on quasars, especially in the ultraviolet band, yields an amazingly coherent narrative which we present in this paper. Quasars are characterised by strong continuum emission and redshifted emission and absorption lines which includes the famous Lyman $\\alpha$ forest. We present irrefutable evidence in support of (1) the entire line spectrum arising in matter located inside the quasar system, (2) the range of redshifts shown by the lines being due to the variable contribution of the gravitational redshift in the observed line velocity, (3) existence of rotating black holes and of matter inside its ergosphere, (4) quasars located within cosmological redshifts $\\sim 3$, (5) $\\gamma$ ray bursts being explosive events in a quasar. These results are significant and a game-changer when we realise that the absorbing gas has been postulated to exist along the line-of-sight to the quasar and observations have accordingly been interpreted. In light of these definitive results which uniquely...

  9. Absorbing Outflows in AGN

    Science.gov (United States)

    Mathur, Smita

    2002-01-01

    The goal of this program was a comprehensive multiwavelength study of absorption phenomena in active galactic nuclei (AGN). These include a variety of associated absorption systems: X-ray warm absorbers, X-ray cold absorbers. UV absorbers with high ionization lines, MgII absorbers, red quasars and BALQSOs. The aim is to determine the physical conditions in the absorbing outflows, study their inter-relations and their role in AGN. We designed several observing programs to achieve this goal: X-ray spectroscopy, UV spectroscopy, FLAY spectroscopy and X-ray imaging. We were very successful towards achieving the goal over the five year period as shown through following observing programs and papers. Copies of a few papers are attached with this report.

  10. Distribution of Doppler Redshifts of Associated Absorbers of SDSS Quasars

    Indian Academy of Sciences (India)

    Cai-Juan Pan; Zhi-Fu Chen

    2013-12-01

    Doppler redshifts of a sample of Mg II associated absorbers of SDSS DR7 quasars are analysed. We find that there might be three Gaussian components in the distribution of the Doppler redshift. The first Gaussian component, with the peak being located at Dopp = -0.0074, probably arises from absorbers with outflow histories observed in the direction close to jets of quasars. The second Gaussian component, with the peak being located at Dopp = -0.0017, possibly arises from absorbers with outflow histories observed in the direction far away from jets of quasars. Whereas, the third Gaussian component, with the peak being located at Dopp = -0.0004, might arise from the random motion of absorbers with respect to quasars.

  11. Probing the circumgalactic medium of active galactic nuclei with background quasars

    CERN Document Server

    Kacprzak, Glenn G; Murphy, Michael T; Cooke, Jeff

    2014-01-01

    We performed a detailed study of the extended cool gas, traced by MgII absorption [$W_r(2796)\\geq0.3$~{\\AA}], surrounding 14 narrow-line active galactic nuclei (AGNs) at 0.1250$ km/s, indicating outflowing gas. The 2/2 intrinsic MgII systems have outflow velocities a factor of $\\sim4$ higher than the NaID outflow velocities. Our results are consistent with AGN-driven outflows destroying the cool gas within their halos, which dramatically decreases their cool gas covering fraction, while star-burst driven winds are expelling cool gas into their circumgalactic media (CGM). This picture appears contrary to quasar--quasar pair studies which show that the quasar CGM contains significant amounts of cool gas whereas intrinsic gas found `down-the-barrel' of quasars reveals no cool gas. We discuss how these results are complementary and provide support for the AGN unified model.

  12. Chandra Observations of 12 Luminous Red Quasars

    Energy Technology Data Exchange (ETDEWEB)

    Urrutia, T; Lacy, M; Gregg, M D; Becker, R H

    2005-03-11

    The authors present results of a study of 12 dust-reddened quasars with 0.4 < z < 2.65 and reddenings in the range 0.15 < E(B-V) < 1.7. They obtained ACIS-S X-ray spectra of these quasars, estimated the column densities towards them, and hence obtained the gas:dust ratios in the material obscuring the quasar. They detect all but one of the red quasars in the X-rays. Even though there is no obvious correlation between the X-ray determined column densities of the sources and their optical color or reddening, all of the sources show absorbed X-ray spectra. When they correct the luminosity for absorption, they can be placed among luminous quasars; therefore their objects belong to the group of high luminosity analogues of the sources contributing to the X-ray background seen in deep X-ray observations. Such sources are also found in serendipitous shallow X-ray surveys. There is a hint that the mean spectral slope of the red quasar is higher than that of normal, unobscured quasars, which could be an indication for higher accretion rates and/or an evolutionary effect. They investigate the number density of these sources compared to type 2 AGN based on the X-ray background and estimate how many moderate luminosity red quasars may be found in deep X-ray fields.

  13. Ultra-fast outflows (aka UFOs) from AGNs and QSOs

    Science.gov (United States)

    Cappi, M.; Tombesi, F.; Giustini, M.

    During the last decade, strong observational evidence has been accumulated for the existence of massive, high velocity winds/outflows (aka Ultra Fast Outflows, UFOs) in nearby AGNs and in more distant quasars. Here we briefly review some of the most recent developments in this field and discuss the relevance of UFOs for both understanding the physics of accretion disk winds in AGNs, and for quantifying the global amount of AGN feedback on the surrounding medium.

  14. Ultra-fast outflows (aka UFOs) from AGNs and QSOs

    CERN Document Server

    Cappi, M; Giustini, M

    2013-01-01

    During the last decade, strong observational evidence has been accumulated for the existence of massive, high velocity winds/outflows (aka Ultra Fast Outflows, UFOs) in nearby AGNs and in more distant quasars. Here we briefly review some of the most recent developments in this field and discuss the relevance of UFOs for both understanding the physics of accretion disk winds in AGNs, and for quantifying the global amount of AGN feedback on the surrounding medium.

  15. Probing Quasar Winds Using Intrinsic Narrow Absorption Lines

    Science.gov (United States)

    Culliton, Christopher S.; Charlton, Jane C.; Eracleous, Michael; Roberts, Amber; Ganguly, Rajib; Misawa, Toru; Muzahid, Sowgat

    2017-01-01

    Quasar outflows are important for understanding the accretion and growth processes of the central black hole. Furthermore, outflows potentially have a role in providing feedback to the galaxy, and halting star formation and infall of gas. The geometry and density of these outflows remain unknown, especially as a function of ionization and velocity. Having searched ultraviolet spectra at both high redshift (VLT/UVES; 1.4physically associated with) the quasar. We identify intrinsic NALs with a wide range of properties, including ejection velocity, coverage fraction, and ionization level. We also consider the incidence of intrinsic absorbers as a function of quasar properties (optical, radio and X-ray fluxes), and find that radio properties and quasar orientation are influential in determining if a quasar is likely to host an intrinsic system. We find that there is a continuum of properties within the intrinsic NAL sample, rather than discrete families, ranging from partially covered CIV systems with black Lya and with a separate low ionization gas phase to partially covered NV systems with partially covered Lya and without detected low ionization gas. Additionally, we construct a model describing the spatial distributions, geometries, and varied ionization structures of intrinsic NALs.

  16. Quasar feedback in the early Universe: the case of SDSS J1148+5251

    NARCIS (Netherlands)

    Valiante, Rosa; Schneider, Raffaella; Maiolino, Roberto; Salvadori, Stefania; Bianchi, Simone

    2012-01-01

    Galaxy-scale gas outflows triggered by active galactic nuclei have been proposed as a key physical process to regulate the co-evolution of nuclear black holes and their host galaxies. The recent detection of a massive gas outflow in one of the most distant quasars, SDSS J1148+5251 at z= 6.4,

  17. Quasar feedback in the early Universe : The case of SDSS J1148+5251

    NARCIS (Netherlands)

    Valiante, Rosa; Schneider, Raffaella; Maiolino, Roberto; Salvadori, Stefania; Bianchi, Simone

    2012-01-01

    Galaxy-scale gas outflows triggered by active galactic nuclei have been proposed as a key physical process to regulate the co-evolution of nuclear black holes and their host galaxies. The recent detection of a massive gas outflow in one of the most distant quasars, SDSS J1148+5251 at z = 6.4,

  18. Broad absorption line (BAL) quasars as a class of low luminosity AGNs

    CERN Document Server

    Kunert-Bajraszewska, M; Roskowinski, C; Gawronski, M

    2015-01-01

    Broad absorption lines seen in some quasars prove the existence of ionized plasma outflows from the accretion disk. Outflows together with powerful jets are important feedback processes. Understanding physics behind BAL outflows might be a key to comprehend Galaxy Evolution as a whole. First radio-loud BAL quasar was discovered in 1997 and this discovery has opened new possibilities for studies of the BAL phenomena, this time on the basis of radio emission. However, information about the radio structures, orientation and age of BAL quasars is still very limited due to weak radio emission and small sizes of these objects. Our high-resolution radio survey of a sample of BAL quasars aims to increase our knowledge about these objects. In this article, we present some conclusions arising from our research.

  19. Quasars with P v broad absorption in BOSS data release 9

    Science.gov (United States)

    Capellupo, D. M.; Hamann, F.; Herbst, H.; Brandt, W. N.; Ge, J.; Pâris, I.; Petitjean, P.; Schneider, D. P.; Streblyanska, A.; York, D.

    2017-07-01

    Broad absorption lines (BALs) found in a significant fraction of quasar spectra identify high-velocity 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 C iv 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.

  20. BAL Quasars without intrinsic X-ray absorption

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ While observing a sample of quasars with broad absorption line (BAL) in their spectra, Prof. WANG Junxian and his colleagues Prof. WANG Tinggui and Dr. ZHOU Hongyan with the Center for Astrophysics at the University of Science and Technology of China (USTC) discovered that unlike most of BAL quasars, two of the observed do not show intrinsic X-ray absorption, indicating a different composition of matter in their outflows. This might help us better understand how black holes devour and project gases, according to the astronomers.

  1. Changing Look Quasars

    Science.gov (United States)

    Green, Paul J.; MacLeod, Chelsea; Anderson, Scott F.; Eracleous, Michael; Ruan, John J.; Runnoe, Jessie C.; Graham, Matthew J.

    2017-01-01

    Accretion onto black holes (BH) illuminates fascinating physics from the stellar mass BHs in Galactic X-ray binaries (XRBs) to the supermassive black holes (SMBH) in Seyferts and quasars. Alas, BH accretion regions are too compact to be spatially resolved. Temporal changes in XRB spectral states have gone a long way to unravel the accretion physics in XRBs, and suggest powerful theoretical and observational analogies to quasars. However, simple mass scaling to SMBHs suggests impractically long timescales (millenia) for accretion state transitions in quasars. However, large spectral state changes in quasars have now been detected that both inform and invigorate debates about accretion theory and the nature of historical quasar classes (e.g., Type 1 vs Type 2). In the last couple of years, a dozen luminous "changing-look quasars" (CLQs) were discovered to exhibit strong, persistent changes in luminosity, accompanied by the dramatic emergence or disappearance of broad emission-line (BEL) components. The availability of repeat spectroscopy for large samples of quasars provided by Sloan Digital Sky Survey (SDSS) and its ongoing Time Domain Spectroscopic Survey (TDSS) now extend this rare and remarkable phenomenon to regimes of luminosity and redshift that overlap the huge cosmological samples of quasars in the SDSS. We review the current understanding of these events, and upcoming possibilities for their detection, characterization and modeling.

  2. Gravitational lensing of quasars

    CERN Document Server

    Eigenbrod, Alexander

    2013-01-01

    The universe, in all its richness, diversity and complexity, is populated by a myriad of intriguing celestial objects. Among the most exotic of them are gravitationally lensed quasars. A quasar is an extremely bright nucleus of a galaxy, and when such an object is gravitationally lensed, multiple images of the quasar are produced – this phenomenon of cosmic mirage can provide invaluable insights on burning questions, such as the nature of dark matter and dark energy. After presenting the basics of modern cosmology, the book describes active galactic nuclei, the theory of gravitational lensing, and presents a particular numerical technique to improve the resolution of astronomical data. The book then enters the heart of the subject with the description of important applications of gravitational lensing of quasars, such as the measurement of the famous Hubble constant, the determination of the dark matter distribution in galaxies, and the observation of the mysterious inner parts of quasars with much higher r...

  3. Outflow and metallicity in the broad-line region of low-redshift active galactic nuclei

    CERN Document Server

    Shin, Jaejin; Woo, Jong-Hak

    2016-01-01

    Outflows in active galactic nuclei (AGNs) are crucial to understand in investigating the co-evolution of supermassive black holes (SMBHs) and their host galaxies since outflows may play an important role as an AGN feedback mechanism. Based on the archival UV spectra obtained with HST and IUE, we investigate outflows in the broad-line region (BLR) in low-redshift AGNs (z < 0.4) through the detailed analysis of the velocity profile of the CIV emission line. We find a dependence of the outflow strength on the Eddington ratio and the BLR metallicity in our low-redshift AGN sample, which is consistent with the earlier results obtained for high-redshift quasars. These results suggest that the BLR outflows, gas accretion onto SMBH, and past star-formation activity in the host galaxies are physically related in low-redshift AGNs as in powerful high-redshift quasars.

  4. AGN feedback on molecular gas reservoirs in quasars at z 2.4

    Science.gov (United States)

    Carniani, S.; Marconi, A.; Maiolino, R.; Feruglio, C.; Brusa, M.; Cresci, G.; Cano-Díaz, M.; Cicone, C.; Balmaverde, B.; Fiore, F.; Ferrara, A.; Gallerani, S.; La Franca, F.; Mainieri, V.; Mannucci, F.; Netzer, H.; Piconcelli, E.; Sani, E.; Schneider, R.; Shemmer, O.; Testi, L.

    2017-09-01

    We present new ALMA observations aimed at mapping molecular gas reservoirs through the CO(3-2) transition in three quasars at z ≃ 2.4, LBQS 0109+0213, 2QZ J002830.4-281706, and [HB89] 0329-385. Previous [Oiii]λ5007 observations of these quasars showed evidence for ionised outflows quenching star formation in their host galaxies. Systemic CO(3-2) emission has been detected only in one quasar, LBQS 0109+0213, where the CO(3-2) emission is spatially anti-correlated with the ionised outflow, suggesting that most of the molecular gas may have been dispersed or heated in the region swept by the outflow. In all three sources, including the one detected in CO, our constraints on the molecular gas mass indicate a significantly reduced reservoir compared to main-sequence galaxies at the same redshift, supporting a negative feedback scenario. In the quasar 2QZ J002830.4-281706, we tentatively detect an emission line blob blue-shifted by v - 2000 km s-1 with respect to the galaxy systemic velocity and spatially offset by 0.2'' (1.7 kpc) with respect to the ALMA continuum peak. Interestingly, such emission feature is coincident in both velocity and space with the ionised outflow as seen in [Oiii]λ5007. This tentative detection must be confirmed with deeper observations but, if real, it could represent the molecular counterpart of the ionised gas outflow driven by the Active Galactic Nucleus (AGN). Finally, in all ALMA maps we detect the presence of serendipitous line emitters within a projected distance 160 kpc from the quasars. By identifying these features with the CO(3-2) transition, we find that the serendipitous line emitters would be located within | Δv | quasars, hence suggesting an overdensity of galaxies in two out of three quasars.

  5. Functional Regression for Quasar Spectra

    CERN Document Server

    Ciollaro, Mattia; Freeman, Peter; Genovese, Christopher; Lei, Jing; O'Connell, Ross; Wasserman, Larry

    2014-01-01

    The Lyman-alpha forest is a portion of the observed light spectrum of distant galactic nuclei which allows us to probe remote regions of the Universe that are otherwise inaccessible. The observed Lyman-alpha forest of a quasar light spectrum can be modeled as a noisy realization of a smooth curve that is affected by a `damping effect' which occurs whenever the light emitted by the quasar travels through regions of the Universe with higher matter concentration. To decode the information conveyed by the Lyman-alpha forest about the matter distribution, we must be able to separate the smooth `continuum' from the noise and the contribution of the damping effect in the quasar light spectra. To predict the continuum in the Lyman-alpha forest, we use a nonparametric functional regression model in which both the response and the predictor variable (the smooth part of the damping-free portion of the spectrum) are function-valued random variables. We demonstrate that the proposed method accurately predicts the unobserv...

  6. Quasars: A Progress Report.

    Science.gov (United States)

    Weedman, Daniel

    1988-01-01

    Reports on some of the discoveries over the last quarter century regarding quasars including spectra and energy sources, formation and evolution, and cosmological probes. Describes some of the fundamental mysteries that remain. (CW)

  7. Testing quasar unification: radiative transfer in clumpy winds

    Science.gov (United States)

    Matthews, J. H.; Knigge, C.; Long, K. S.; Sim, S. A.; Higginbottom, N.; Mangham, S. W.

    2016-05-01

    Various unification schemes interpret the complex phenomenology of quasars and luminous active galactic nuclei (AGN) in terms of a simple picture involving a central black hole, an accretion disc and an associated outflow. Here, we continue our tests of this paradigm by comparing quasar spectra to synthetic spectra of biconical disc wind models, produced with our state-of-the-art Monte Carlo radiative transfer code. Previously, we have shown that we could produce synthetic spectra resembling those of observed broad absorption line (BAL) quasars, but only if the X-ray luminosity was limited to 1043 erg s-1. Here, we introduce a simple treatment of clumping, and find that a filling factor of ˜0.01 moderates the ionization state sufficiently for BAL features to form in the rest-frame UV at more realistic X-ray luminosities. Our fiducial model shows good agreement with AGN X-ray properties and the wind produces strong line emission in, e.g., Lyα and C IV 1550 Å at low inclinations. At high inclinations, the spectra possess prominent LoBAL features. Despite these successes, we cannot reproduce all emission lines seen in quasar spectra with the correct equivalent-width ratios, and we find an angular dependence of emission line equivalent width despite the similarities in the observed emission line properties of BAL and non-BAL quasars. Overall, our work suggests that biconical winds can reproduce much of the qualitative behaviour expected from a unified model, but we cannot yet provide quantitative matches with quasar properties at all viewing angles. Whether disc winds can successfully unify quasars is therefore still an open question.

  8. The Growth of Central Black Hole and the Ionization Instability of Quasar Disk

    Science.gov (United States)

    Lu, Ye; Cheng, K. S.; Zhang, S. N.

    2003-01-01

    A possible accretion model associated with the ionization instability of quasar disks is proposed to address the growth of the central black hole harbored in the host galaxy. The evolution of quasars in cosmic time is assumed to change from a highly active state to a quiescent state triggered by the S-shaped ionization instability of the quasar accretion disk. For a given external mass transfer rate supplied by the quasar host galaxy, ionization instability can modify accretion rate in the disk and separates the accretion flows of the disk into three different phases, like a S-shape. We suggest that the bright quasars observed today are those quasars with disks in the upper branch of S-shaped instability, and the faint or 'dormant' quasars are simply the system in the lower branch. The middle branch is the transition state which is unstable. We assume the quasar disk evolves according to the advection-dominated inflow-outflow solutions (ADIOS) configuration in the stable lower branch of S-shaped instability, and Eddington accretion rate is used to constrain the accretion rate in each phase. The mass ratio between black hole and its host galactic bulge is a nature consequence of ADIOS. Our model also demonstrates that a seed black hole (BH) similar to those found in spiral galaxies today is needed to produce a BH with a final mass 2 x 10(exp 8) solar mases.

  9. Quasar Absorption Studies

    Science.gov (United States)

    Mushotzky, Richard (Technical Monitor); Elvis, Martin

    2004-01-01

    The aim of the proposal is to investigate the absorption properties of a sample of inter-mediate redshift quasars. The main goals of the project are: Measure the redshift and the column density of the X-ray absorbers; test the correlation between absorption and redshift suggested by ROSAT and ASCA data; constrain the absorber ionization status and metallicity; constrain the absorber dust content and composition through the comparison between the amount of X-ray absorption and optical dust extinction. Unanticipated low energy cut-offs where discovered in ROSAT spectra of quasars and confirmed by ASCA, BeppoSAX and Chandra. In most cases it was not possible to constrain adequately the redshift of the absorber from the X-ray data alone. Two possibilities remain open: a) absorption at the quasar redshift; and b) intervening absorption. The evidences in favour of intrinsic absorption are all indirect. Sensitive XMM observations can discriminate between these different scenarios. If the absorption is at the quasar redshift we can study whether the quasar environment evolves with the Cosmic time.

  10. The Discovery of Quasars

    CERN Document Server

    Kellermann, K I

    2013-01-01

    Although the extragalactic nature of quasars was discussed as early as 1960, it was rejected largely because of preconceived ideas about what appeared to be an unrealistically high radio and optical luminosity. Following the 1962 occultations of the strong radio source 3C 273 at Parkes, and the subsequent identification with an apparent stellar object, Maarten Schmidt recognized that the relatively simple hydrogen line Balmer series spectrum implied a redshift of 0.16 Successive radio and optical measurements quickly led to the identification of other quasars with increasingly large redshifts and the general, although for some decades not universal, acceptance of quasars as being by far the most distant and the most luminous objects in the Universe. Curiously, 3C 273, which is one of the strongest extragalactic sources in the sky, was first catalogued in 1959 and the magnitude 13 optical counterpart was observed at least as early as 1887. Since 1960, much fainter optical counterparts were being routinely iden...

  11. Astrometric Redshifts for Quasars

    CERN Document Server

    Kaczmarczik, Michael C; Mehta, Sajjan S; Schlegel, David J

    2009-01-01

    The wavelength dependence of atmospheric refraction causes differential chromatic refraction (DCR), whereby objects imaged at different optical/UV wavelengths are observed at slightly different positions in the plane of the detector. Strong spectral features induce changes in the effective wavelengths of broad-band filters that are capable of producing significant positional offsets with respect to standard DCR corrections. We examine such offsets for broad-emission-line (type 1) quasars from the Sloan Digital Sky Survey (SDSS) spanning 0quasar spectrum with the SDSS bandpasses as a function of redshift and airmass. This astrometric information can be used to break degeneracies in photometric redshifts of quasars (or other emission-line sources) and, for extreme cases, may be suitable for determining "astrometric redshifts". On the SDSS's southern equatorial stripe, where it is pos...

  12. Lensed Quasar Hosts

    CERN Document Server

    Peng, C Y; Rix, H W; Keeton, C R; Falco, E E; Kochanek, C S; Lehár, J; McLeod, B A; Peng, Chien Y.; Impey, Chris D.; Rix, Hans-Walter; Keeton, Charles R.; Falco, Emilio E.; Kochanek, Chris S.; Lehar, Joseph; Leod, Brian A. Mc

    2006-01-01

    Gravitational lensing assists in the detection of quasar hosts by amplifying and distorting the host light away from the unresolved quasar core images. We present the results of HST observations of 30 quasar hosts at redshifts 1 1.7 is a factor of 3--6 higher than the local value. But, depending on the stellar content the ratio may decline at z>4 (if E/S0-like), flatten off to 6--10 times the local value (if Sbc-like), or continue to rise (if Im-like). We infer that galaxy bulge masses must have grown by a factor of 3--6 over the redshift range 3>z>1, and then changed little since z~1. This suggests that the peak epoch of galaxy formation for massive galaxies is above z~1. We also estimate the duty cycle of luminous AGNs at z>1 to be ~1%, or 10^7 yrs, with sizable scatter.

  13. Surveys of Luminous Quasars in the Post-reionization Universe at z=5-6

    Science.gov (United States)

    Yang, Jinyi; Wu, Xue-Bing; Fan, Xiaohui; Wang, Feige; McGreer, Ian D.; Bian, Fuyan; Green, Richard F.; Yang, Qian; Jiang, Linhua; Wang, Ran; Yi, Weimin; UHS Team

    2017-01-01

    Quasars at z ~ 5 to 6, the post-reionization epoch, are crucial tools to explore the evolution of intergalactic medium (IGM), quasar evolution and the early super-massive black hole growth. The quasar luminosity function (QLF) and its evolution at z >~ 5 is also needed to estimate the contribution of quasars to the ionizing background during and after the reionization epoch. McGreer et al. (2013) provided the first complete measurement of the z ~ 5 QLF. However, their work focused on faint quasars over a small sky area; there were only 8 quasars with M1450 4, previous studies have concluded that the number density evolution steepens at high redshift, such that luminous quasars decline as a population more steeply at higher redshift (z ~ 5.5) than from z=4 to 5. However, quasars at redshifts 5.3 Up to date, we have constructed an uniform luminous z ~ 5.5 quasar sample with 26 new quasars. Our final completed sample of quasars at z=5-6 will be used to study QLF, evolution model and IGM evolution in the post-deionization universe.

  14. Understanding the contributions of anthropogenic and biogenic sources to CO enhancements and outflow observed over North America and the western Atlantic Ocean by TES and MOPITT

    Science.gov (United States)

    Choi, Yunsoo; Osterman, Gregory; Eldering, Annmarie; Wang, Yuhang; Edgerton, Eric

    2010-05-01

    We investigate the effects of anthropogenic and biogenic sources on tropospheric CO enhancements and outflow over North America and the Atlantic during July-August 2006, the 3rd warmest summer on record. The analysis is performed using the 3D Regional chEmical trAnsport Model (REAM), satellite data from TES on the Aura satellite, MOPITT on the Terra satellite and surface monitor data from the SEARCH network. The satellite measurements of CO provide insight into the location of regional CO enhancements along with the ability to resolve vertical features. Satellite and surface monitor data are used to compare with REAM, illustrating model's ability to reproduce observed CO concentrations. The REAM model used in this study features CO emissions reduced by 50% from the 1999 EPA NEI and biogenic VOC emissions scaled by EPA-observed isoprene concentrations (20% reduction). The REAM simulations show large variations in surface CO, lower tropospheric CO and column CO, which are also observed by the surface observations and satellite data. Over the US, during July-August 2006, the model estimates monthly CO production from anthropogenic sources (5.3 and 5.1 Tg CO) is generally larger than biogenic sources (4.3 and 3.5 Tg CO). However, the model shows that for very warm days, biogenic sources produce as much CO as anthropogenic sources, a result of increased biogenic production due to warmer temperatures. The satellite data show CO outflow occurs along the East Coast of the US and Canada in July and is more broadly distributed over the Atlantic in August. REAM results show the longitudinally exported CO enhancements from anthropogenic sources (3.3 and 3.9 Tg CO) are larger than biogenic sources (2.8 and 2.7 Tg CO) along the eastern boundary of REAM for July-August 2006. We show that when compared with the impacts of both sources on increasing tropospheric CO exports, the relative impacts in August are greater than in July because of preferable outflow transport.

  15. Radiation pressure confinement - IV. Application to broad absorption line outflows

    CERN Document Server

    Baskin, Alexei; Stern, Jonathan

    2014-01-01

    A fraction of quasars present broad absorption lines, produced by outflowing gas with typical velocities of 3000 - 10,000 km/s. If the outflowing gas fills a significant fraction of the volume where it resides, then it will be highly ionized by the quasar due to its low density, and will not produce the observed UV absorption. The suggestion that the outflow is shielded from the ionizing radiation was excluded by recent observations. The remaining solution is a dense outflow with a filling factor $f<10^{-3}$. What produces such a small $f$? Here we point out that radiation pressure confinement (RPC) inevitably leads to gas compression and the formation of dense thin gas sheets/filaments, with a large gradient in density and ionization along the line of sight. The total column of ionized dustless gas is a few times $10^{22}$ cm$^{-2}$, consistent with the observed X-ray absorption and detectable P V absorption. The predicted maximal columns of various ions show a small dependence on the system parameters, a...

  16. Quasars : The Observational Perspectives

    NARCIS (Netherlands)

    D'Onofrio, Mauro; Marziani, Paola; Sulentic, Jack W.; Shields, Greg; Gaskell, Martin; Boroson, Todd; Laor, Ari; Hawkins, Michael; Pronik, Vladimir; Sergeev, Sergey; Dultzin, Deborah; Grupe, Dirk; Richards, Gordon; Morganti, Raffaella; Volvach, Aleksander; Zamfir, Sebastian; Falcke, Heino; Körding, Elmar; Elvis, Martin; Turner, Tracey Jane; Kembhavi, Ajit; Foschini, Luigi; Neshpor, Yuri; Franceschini, Alberto

    2012-01-01

    The empirical basis of quasar astronomy can be overawing especially in the twenty-first century. A first source of intricacy involves the nomenclature that has evolved to label the multifold phenomenological manifestations now united under the umbrella of active galactic nuclei (AGNs). A further com

  17. A Quasar Turns On

    Science.gov (United States)

    Kohler, Susanna

    2017-02-01

    The intermediate Palomar Transient Factory (iPTF) has discovered a quasar the brightly-shining, active nucleus of a galaxy abruptly turning on in what appears to be the fastest such transition ever seen in such an object.A Rapid TransitionQuasars are expected to show variations in brightness on timescales of hours to millions of years, but its not often that we get to study their major variability in real time! So far, weve discovered only a dozen changing-look quasars active galactic nuclei that exhibit major changes in their spectral class and brightness between observations. Roughly half of these were quasars that turned on and half were quasars that turned off, generally on timescales of maybe 5 or 10 years.The dramatic change in spectrum of iPTF 16bco between the archival SDSS data from 2004 (bottom) and the follow-up spectroscopy from Keck 2+DEIMOS in 2016 (top). [Adapted from Gezari et al. 2017]In June 2016, however, a team of scientists led by Suvi Gezari (University of Maryland) discovered iPTF 16bco, a nuclear transient that wasnt there the last time Palomar checked in 2012. A search through archival Sloan Digital Sky Survey and GALEX data in addition to some follow-up X-ray imaging and spectroscopic observations told the team what they needed to know: iPTF 16bco is a quasar that only just turned on within the 500 days preceding the iPTF observations.This source, in fact, is a 100-million-solar-mass black hole located at the center of a galaxy at a redshift of z= 0.237. In just over a year, the source changed classification from a galaxy with weak narrow-line emission to a quasar with characteristic strong, broad emission lines and a ten-fold increase in continuum brightness! What caused this sudden transition?Instabilities at Fault?iPTF 16bco and the other known changing-look quasars with disappearing (red circles) and appearing (blue circles) broad-line emission. [Adapted from Gezari et al. 2017]Gezari and collaborators used the large number of recent

  18. Quasar emission lines as probes of orientation: implications for disc wind geometries and unification

    Science.gov (United States)

    Matthews, J. H.; Knigge, C.; Long, K. S.

    2017-01-01

    The incidence of broad absorption lines (BALs) in quasar samples is often interpreted in the context of a geometric unification model consisting of an accretion disc and an associated outflow. We use the the Sloan Digital Sky Survey (SDSS) quasar sample to test this model by examining the equivalent widths (EWs) of C IV 1550 Å, Mg II 2800 Å, [O III] 5007 Å and C III] 1909 Å. We find that the emission line EW distributions in BAL and non-BAL quasars are remarkably similar - a property that is inconsistent with scenarios in which a BAL outflow rises equatorially from a geometrically thin, optically thick accretion disc. We construct simple models to predict the distributions from various geometries; these models confirm the above finding and disfavour equatorial geometries. We show that obscuration, line anisotropy and general relativistic effects on the disc continuum are unlikely to hide an EW inclination dependence. We carefully examine the radio and polarisation properties of BAL quasars. Both suggest that they are most likely viewed (on average) from intermediate inclinations, between type 1 and type 2 AGN. We also find that the low-ionization BAL quasars in our sample are not confined to one region of `Eigenvector I' parameter space. Overall, our work leads to one of the following conclusions, or some combination thereof: (i) the continuum does not emit like a geometrically thin, optically thick disc; (ii) BAL quasars are viewed from similar angles to non-BAL quasars, i.e. low inclinations; (iii) geometric unification does not explain the fraction of BALs in quasar samples.

  19. Molecules in Bipolar Outflows

    CERN Document Server

    Tafalla, Mario

    2012-01-01

    Bipolar outflows constitute some of the best laboratories to study shock chemistry in the interstellar medium. A number of molecular species have their abundance enhanced by several orders of magnitude in the outflow gas, likely as a combined result of dust mantle disruption and high temperature gas chemistry, and therefore become sensitive indicators of the physical changes taking place in the shock. Identifying these species and understanding their chemical behavior is therefore of high interest both to chemical studies and to our understanding of the star-formation process. Here we review some of the recent progress in the study of the molecular composition of bipolar outflows, with emphasis in the tracers most relevant for shock chemistry. As we discuss, there has been rapid progress both in characterizing the molecular composition of certain outflows as well as in modeling the chemical processes likely involved. However, a number of limitations still affect our understanding of outflow chemistry. These i...

  20. Kiloparsec-scale outflows are prevalent among luminous AGN: outflows and feedback in the context of the overall AGN population

    CERN Document Server

    Harrison, C M; Mullaney, J R; Swinbank, A M

    2014-01-01

    We present integral field unit (IFU) observations covering the [O III]4959,5007 and H-Beta emission lines of sixteen z~(6-16) kpc in all targets and observe signatures of spherical outflows and bi-polar superbubbles. We show that our targets are representative of z 5x10^41 erg/s) type 2 AGN and that ionised outflows are not only common but also in >=70% (3 sigma confidence) of cases, they are extended over kiloparsec scales. Our study demonstrates that galaxy-wide energetic outflows are not confined to the most extreme star-forming galaxies or radio-luminous AGN; however, there may be a higher incidence of the most extreme outflow velocities in quasars hosted in ultra-luminous infrared galaxies. Both star formation and AGN activity appear to be energetically viable to drive the outflows and we find no definitive evidence that favours one process over the other. Although highly uncertain, we derive mass outflow rates (typically ~10x the SFRs), kinetic energies (~0.5-10% of L[AGN]) and momentum rates (typically...

  1. Investigating the Structure of the Windy Torus in Quasars

    CERN Document Server

    Gallagher, S C; Abado, M M; Keating, S K

    2015-01-01

    Thermal mid-infrared emission of quasars requires an obscuring structure that can be modeled as a magneto-hydrodynamic wind in which radiation pressure on dust shapes the outflow. We have taken the dusty wind models presented by Keating and collaborators that generated quasar mid-infrared spectral energy distributions (SEDs), and explored their properties (such as geometry, opening angle, and ionic column densities) as a function of Eddington ratio and X-ray weakness. In addition, we present new models with a range of magnetic field strengths and column densities of the dust-free shielding gas interior to the dusty wind. We find this family of models -- with input parameters tuned to accurately match the observed mid-IR power in quasar SEDs -- provides reasonable values of the Type 1 fraction of quasars and the column densities of warm absorber gas, though it does not explain a purely luminosity-dependent covering fraction for either. Furthermore, we provide predictions of the cumulative distribution of E(B-V...

  2. Radio jets and outflows of cold gas

    CERN Document Server

    Morganti, Raffaella

    2011-01-01

    Massive gas outflows are considered a key component in the process of galaxy formation and evolution. It is, therefore, not surprising that a lot of effort is going in quantifying their impact via detailed observations. This short contribution presents recent results obtained from HI and CO observations of different objects where the AGN - and in particular the radio jet - is likely playing an important role in producing the gas outflows. These preliminary results are reinforcing the conclusion that these outflows have a complex and multiphase structure where cold gas in different phases (atomic and molecular) is involved and likely represent a major component. These results will also provide important constraints for establishing how the interaction between AGN/radio jet and the surrounding ISM occurs and how efficiently the gas should cool to produce the observed properties of the outflowing gas. HI likely represents an intermediate phase in this process, while the molecular gas would be the final stage. Wh...

  3. MusE GAs FLOw and Wind (MEGAFLOW) I: First MUSE results on background quasars

    CERN Document Server

    Schroetter, Ilane; Wendt, Martin; Contini, Thierry; Finley, Hayley; Pello, Roser; Bacon, Roland; Cantalupo, Sebastiano; Marino, Raffaella; Richard, Johan; Lilly, Simon; Schaye, Joop; Soto, Kurt; Steinmetz, Matthias; Straka, Lorrie A; Wisotzki, Lutz

    2016-01-01

    The physical properties of galactic winds are one of the keys to understand galaxy formation and evolution. These properties can be constrained thanks to background quasar lines of sight (LOS) passing near star-forming galaxies (SFGs). We present the first results of the MusE GAs FLOw and Wind (MEGAFLOW) survey obtained of 2 quasar fields which have 8 MgII absorbers of which 3 have rest-equivalent width greater than 0.8 \\AA. With the new Multi Unit Spectroscopic Explorer (MUSE) spectrograph on the Very Large Telescope (VLT), we detect 6 (75$\\%$) MgII host galaxy candidates withing a radius of 30 arcsec from the quasar LOS. Out of these 6 galaxy--quasar pairs, from geometrical arguments, one is likely probing galactic outflows, two are classified as "ambiguous", two are likely probing extended gaseous disks and one pair seems to be a merger. We focus on the wind$-$pair and constrain the outflow using a high resolution quasar spectra from Ultraviolet and Visual Echelle Spectrograph (UVES). Assuming the metal ab...

  4. Testing Disk-Wind Models with Quasar CIV 1549Å Associated Absorption Lines

    DEFF Research Database (Denmark)

    Vestergaard, Marianne

    2012-01-01

    Narrow associated C IV 1549Å absorption lines (NALs) with a rest equivalent width EW =3 Å detected in z ˜ 2 radio-loud and radio-quiet quasars, (a) exhibit evidence of an origin in radiatively accelerated gas, and (b) may be closely related to broad absorption line (BAL) outflows. These NALs...... and the few BALs detected in this quasar sample obey key predictions of models of radiatively driven disk-winds in which (1) the local disk luminosity launches the wind, (2) the central UV radiation drives it outwards, and (3) the wind acceleration (i.e., terminal velocity) depends on the strength of the X......-ray to UV emission ratio, i.e., aOX. The latter means that quasars with flat aOX (like radio-louds) should not have strong, high-velocity (BAL-like) outflows. These results are of interest not only to studies of disk wind scenarios and quasar structure, but also to studies of quasar feedback: NALs...

  5. Testing Disk-Wind Models with Quasar CIV 1549Å Associated Absorption Lines

    DEFF Research Database (Denmark)

    Vestergaard, Marianne

    2012-01-01

    Narrow associated C IV 1549Å absorption lines (NALs) with a rest equivalent width EW =3 Å detected in z ˜ 2 radio-loud and radio-quiet quasars, (a) exhibit evidence of an origin in radiatively accelerated gas, and (b) may be closely related to broad absorption line (BAL) outflows. These NALs...... and the few BALs detected in this quasar sample obey key predictions of models of radiatively driven disk-winds in which (1) the local disk luminosity launches the wind, (2) the central UV radiation drives it outwards, and (3) the wind acceleration (i.e., terminal velocity) depends on the strength of the X......-ray to UV emission ratio, i.e., aOX. The latter means that quasars with flat aOX (like radio-louds) should not have strong, high-velocity (BAL-like) outflows. These results are of interest not only to studies of disk wind scenarios and quasar structure, but also to studies of quasar feedback: NALs...

  6. Muse Gas Flow and Wind (MEGAFLOW). I. First MUSE Results on Background Quasars

    Science.gov (United States)

    Schroetter, I.; Bouché, N.; Wendt, M.; Contini, T.; Finley, H.; Pelló, R.; Bacon, R.; Cantalupo, S.; Marino, R. A.; Richard, J.; Lilly, S. J.; Schaye, J.; Soto, K.; Steinmetz, M.; Straka, L. A.; Wisotzki, L.

    2016-12-01

    The physical properties of galactic winds are one of the keys to understand galaxy formation and evolution. These properties can be constrained thanks to background quasar lines of sight (LOS) passing near star-forming galaxies (SFGs). We present the first results of the MusE GAs FLOw and Wind survey obtained from two quasar fields, which have eight Mg ii absorbers of which three have rest equivalent width greater than 0.8 Å. With the new Multi Unit Spectroscopic Explorer (MUSE) spectrograph on the Very Large Telescope (VLT), we detect six (75%) Mg ii host galaxy candidates within a radius of 30″ from the quasar LOS. Out of these six galaxy-quasar pairs, from geometrical argument, one is likely probing galactic outflows, where two are classified as “ambiguous,” two are likely probing extended gaseous disks and one pair seems to be a merger. We focus on the wind-pair and constrain the outflow using a high-resolution quasar spectra from the Ultraviolet and Visual Echelle Spectrograph. Assuming the metal absorption to be due to ga;s flowing out of the detected galaxy through a cone along the minor axis, we find outflow velocities in the order of ≈150 {km} {{{s}}}-1 (i.e., smaller than the escape velocity) with a loading factor, η ={\\dot{M}}{out}/{{SFR}}, of ≈0.7. We see evidence for an open conical flow, with a low-density inner core. In the future, MUSE will provide us with about 80 multiple galaxy-quasar pairs in two dozen fields. Based on observations made at the ESO telescopes under programs 094.A-0211(B) and 293.A-5038(A).

  7. Evaluating and improving the redshifts of z > 2.2 quasars

    Science.gov (United States)

    Mason, Michelle; Brotherton, Michael S.; Myers, Adam

    2017-08-01

    Quasar redshifts require the best possible precision and accuracy for a number of applications, such as setting the velocity scale for outflows as well as measuring small-scale quasar-quasar clustering. The most reliable redshift standard in luminous quasars is arguably the narrow [O iii] λλ4959, 5007 emission line doublet in the rest-frame optical. We use previously published [O iii] redshifts obtained using near-infrared spectra in a sample of 45 high-redshift (z > 2.2) quasars to evaluate redshift measurement techniques based on rest-frame ultraviolet spectra. At redshifts above z = 2.2, the Mg ii λ2798 emission line is not available in observed-frame optical spectra and the most prominent unblended and unabsorbed spectral feature available is usually C iv λ1549. Peak and centroid measurements of the C iv profile are often blueshifted relative to the rest-frame of the quasar, which can significantly bias redshift determinations. We show that redshift determinations for these high-redshift quasars are significantly correlated with the emission-line properties of C iv (i.e. the equivalent width, or EW, and the full width at half-maximum, or FWHM) as well as the luminosity, which we take from the Sloan Digital Sky Survey Data Release 7. We demonstrate that empirical corrections based on multiple regression analyses yield significant improvements in both the precision and accuracy of the redshifts of the most distant quasars and are required to establish consistency with redshifts determined in more local quasars.

  8. Dust Obscured Quasars: A Missing Link in Quasar Evolution

    Science.gov (United States)

    Glikman, Eilat; Djorgovski, S. G.; Mahabal, A.; Lacy, M.

    2007-12-01

    A host of observational evidence over several decades of research has suggested a formation and evolutionary link between the growth of supermassive black holes, quasar activity and the build-up of the stellar populations in their host galaxies. Such evolutionary scenarios have been invoked to explain the presence of buried AGN seen in ultraluminous infrared galaxies, a high fraction of which also show evidence of merging and interaction. However, the morphologies of luminous, blue quasars show no signs of interaction. Their hosts are mostly undistrubed elliptical galaxies. These seemingly conflicting observations suggest a missing link in the evolutionary path where the dust that completely buried the ULIRG is being cleared, eventually to reveal an unobscured, luminous quasar. This missing link may be a population of highly reddened, but not completely obscured quasars. We have constructed asample of dust obscured quasars using FIRST and 2MASS. We find that for K CRATES flat-spectrum radio catalog.

  9. The Search for Molecular Outflows in Local Volume AGNs with Herschel-PACS

    Science.gov (United States)

    Stone, M.; Veilleux, S.; Meléndez, M.; Sturm, E.; Graciá-Carpio, J.; González-Alfonso, E.

    2016-08-01

    We present the results from a systematic search for galactic-scale, molecular (OH 119 μm) outflows in a sample of 52 Local Volume (d\\lt 50 Mpc) Burst Alert Telescope detected active galactic nuclei (BAT AGNs) with Herschel-PACS. We combine the results from our analysis of the BAT AGNs with the published Herschel/PACS data of 43 nearby (z\\lt 0.3) galaxy mergers, mostly ultra-luminous infrared galaxies (ULIRGs) and QSOs. The objects in our sample of BAT AGNs have, on average, ˜ 10{--}100 times lower AGN luminosities, star formation rates, and stellar masses than those of the ULIRG and QSO samples. OH 119 μm is detected in 42 of our BAT AGN targets. Evidence for molecular outflows (i.e., OH absorption profiles with median velocities more blueshifted than -50 km s-1 and/or blueshifted wings with 84% velocities less than -300 km s-1) is seen in only four BAT AGNs (NGC 7479 is the most convincing case). Evidence for molecular inflows (i.e., OH absorption profiles with median velocities more redshifted than 50 km s-1) is seen in seven objects, although an inverted P-Cygni profile is detected unambiguously in only one object (Circinus). Our data show that both the starburst and AGN contribute to driving OH outflows, but the fastest OH winds require AGNs with quasar-like luminosities. We also confirm that the total absorption strength of OH 119 μm is a good proxy for dust optical depth as it correlates strongly with the 9.7 μm silicate absorption feature, a measure of obscuration originating in both the nuclear torus and host galaxy disk. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

  10. An X-ray view of quasars

    CERN Document Server

    Singh, K P

    2013-01-01

    I present an overview of observational studies of quasars of all types, with particular emphasis on X-ray observational studies. The presentation is based on the most popularly accepted unified picture of quasars - collectively referred to as AGN (active galactic nuclei) in this review. Characteristics of X-ray spectra and X-ray variability obtained from various X-ray satellites over the last 5 decades have been presented and discussed. The contribution of AGN in understanding the cosmic X-ray background is discussed very briefly. Attempt has been made to provide up-to-date information; however, this is a vast subject and this presentation is not intended to be comprehensive.

  11. Constraining FeLoBAL outflows from absorption line variability

    CERN Document Server

    McGraw, S M; Hamann, F W; Capellupo, D M; Gallagher, S C; Brandt, W N

    2015-01-01

    FeLoBALs are a rare class of quasar outflows with low-ionization broad absorption lines (BALs), 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 between 0.7 and 1.9 over rest frame time-scales of approximately 10 d to 7.6 yr. We detect absorption line variability with greater than 8 sigma 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 2796, 2803 doublet, Mg I 2852, and excited state Ni II multiplets. The observed variability along with evidence of saturation in the absorption lines favors transverse motions of gas across the line of sight (LOS) as the preferred scenario, and allows us to constrain the outflow distance from th...

  12. The Kinematics of Quasar Broad Emission Line Regions Using a Disk-Wind Model

    Science.gov (United States)

    Yong, Suk Yee; Webster, Rachel L.; King, Anthea L.; Bate, Nicholas F.; O'Dowd, Matthew J.; Labrie, Kathleen

    2017-09-01

    The structure and kinematics of the broad line region in quasars are still unknown. One popular model is the disk-wind model that offers a geometric unification of a quasar based on the viewing angle. We construct a simple kinematical disk-wind model with a narrow outflowing wind angle. The model is combined with radiative transfer in the Sobolev, or high velocity, limit. We examine how angle of viewing affects the observed characteristics of the emission line. The line profiles were found to exhibit distinct properties depending on the orientation, wind opening angle, and region of the wind where the emission arises.

  13. The optical-UV emissivity of quasars: dependence on black hole mass and radio loudness

    CERN Document Server

    Shankar, Francesco; Knigge, Christian; Matthews, James; Buckland, Rachel; Hryniewicz, Krzysztof; Sivakoff, Gregory; Dai, Xinyu; Richardson, Kayleigh; Riley, Jack; Gray, James; La Franca, Fabio; Altamirano, Diego; Croston, Judith; Gandhi, Poshak; Hoenig, Sebastian F; McHardy, Ian; Middleton, Matthew

    2016-01-01

    We analyzed a large sample of radio-loud and radio-quiet quasar spectra at redshift 1.0 < z < 1.2 to compare the inferred underlying quasar continuum slopes (after removal of the host galaxy contribution) with accretion disk models. The latter predict redder (decreasing) alpha_3000 continuum slopes (L_\

  14. A multi-wavelength survey of obscured and reddened quasars at the peak of galaxy formation

    Science.gov (United States)

    Alexandroff, Rachael

    2017-01-01

    While in the nearby universe the unification model seems firmly established, we are now seeing hints that at the peak of quasar activity and black hole growth (z~2.5) both obscured and reddened quasars may represent not just a specific quasar orientation but instead a unique stage of quasar evolution. Our group has developed several observational techniques to identify obscured and highly reddened quasars at z~2.5 using a combination of the SDSS spectroscopy and WISE photometry. Our sample contains objects with some of the most extreme ionized gas velocities observed (> 5000 km/s), indicating wind speeds too large to be contained by the galaxy potential though they are radio quiet. I will present both our sample selection and initial results from multi-wavelength follow-up of this sample using near-infrared spectroscopy, Keck spectropolarimentry and the VLA to test the AGN unification model and search for evidence of galaxy-wide quasar winds. High levels of polarized light (reaching ~20% of the total continuum emission in some cases) and changes in the polarization fraction and position angle across emission lines may argue for the presence of dusty outflows in our objects. This is supported by evidence from stacking analysis in the radio that presents a correlation between the observed outflow speeds in ionized gas (as measured by [OIII]) and the radio luminosity—arguing for a wind origin for the radio emission in these objects as well. The most extreme of these objects may thus represent the “blowout phase” of AGN evolution that proceeds or accompanies the cessation of star formation in the host galaxy due to the effects of radiatively-driven quasar driven winds.

  15. Quasars in the Cosmic Environment

    NARCIS (Netherlands)

    D'Onofrio, Mauro; Marziani, Paola; Sulentic, Jack W.; Dultzin, Deborah; Richards, Gordon; Knapen, Johan; Shlosman, Isaac; Morganti, Raffaella; Falomo, Renato; Hawkins, Mike; Cavaliere, Alfonso; McLure, Ross; Shields, Greg; Netzer, Hagai; Proga, Daniel; Franceschini, Alberto; Fan, Xiaoui; Elvis, Martin

    2012-01-01

    We now consider the environment of quasars in the widest possible sense, from the circumnuclear regions to very large scales of hundreds of kiloparsecs. The circumgalactic environment of nearby quasars has been widely studied since the late 1960s in an attempt to test its influence on the triggering

  16. Outshining the quasars at reionization

    DEFF Research Database (Denmark)

    Watson, D.; Reeves, J.N.; Hjorth, J.

    2006-01-01

    Gamma Rays: Bursts, Galaxies: Intergalactic Medium, Galaxies: Quasars: Absorption Lines, X-Rays: Galaxies, X-Rays: General Udgivelsesdato: 19 January......Gamma Rays: Bursts, Galaxies: Intergalactic Medium, Galaxies: Quasars: Absorption Lines, X-Rays: Galaxies, X-Rays: General Udgivelsesdato: 19 January...

  17. On the Radio and Optical Luminosity Evolution of Quasars

    Energy Technology Data Exchange (ETDEWEB)

    Singal, J.; /KIPAC, Menlo Park /SLAC; Petrosian, V.; /KIPAC, Menlo Park /SLAC /Stanford U., Phys. Dept. /Stanford U., Appl. Phys. Dept.; Lawrence, A.; /Edinburgh U., Inst. Astron.; Stawarz, L.; /JAXA, Sagamihara /Jagiellonian U., Astron. Observ.

    2011-05-20

    We calculate simultaneously the radio and optical luminosity evolutions of quasars, and the distribution in radio loudness R defined as the ratio of radio and optical luminosities, using a flux limited data set containing 636 quasars with radio and optical fluxes from White et al. We first note that when dealing with multivariate data it is imperative to first determine the true correlations among the variables, not those introduced by the observational selection effects, before obtaining the individual distributions of the variables. We use the methods developed by Efron and Petrosian which are designed to obtain unbiased correlations, distributions, and evolution with redshift from a data set truncated due to observational biases. It is found that as expected the population of quasars exhibits strong positive correlation between the radio and optical luminosities and that this correlation deviates from a simple linear relation in a way indicating that more luminous quasars are more radio loud. We also find that there is a strong luminosity evolution with redshift in both wavebands, with significantly higher radio than optical evolution. We conclude that the luminosity evolution obtained by arbitrarily separating the sources into radio loud (R > 10) and radio quiet (R < 10) populations introduces significant biases that skew the result considerably. We also construct the local radio and optical luminosity functions and the density evolution. Finally, we consider the distribution of the radio loudness parameter R obtained from careful treatment of the selection effects and luminosity evolutions with that obtained from the raw data without such considerations. We find a significant difference between the two distributions and no clear sign of bi-modality in the true distribution. Our results indicate therefore, somewhat surprisingly, that there is no critical switch in the efficiency of the production of disk outflows/jets between very radio quiet and very radio

  18. Quasars Probing Quasars VI. Excess HI Absorption Within One Proper Mpc of z~2 Quasars

    CERN Document Server

    Prochaska, J Xavier; Lee, Khee-Gan; Cantalupo, Sebastiano; Bovy, Jo; Djorgovski, S G; Ellison, Sara L; Lau, Marie Wingyee; Martin, Crystal L; Myers, Adam; Rubin, Kate H R; Simcoe, Robert A

    2013-01-01

    With close pairs of quasars at different redshifts, a background quasar sightline can be used to study a foreground quasar's environment in absorption. We use a sample of 650 projected quasar pairs to study the HI Lya absorption transverse to luminous, z~2 quasars at proper separations of 30kpc 17.3) at separations R<200kpc, which decreases to ~20% at R~1Mpc, but still represents a significant excess over the cosmic average. This excess of optically thick absorption can be described by a quasar-absorber cross-correlation function xi_QA(r) = (r/r_0)^gamma with a large correlation length r_0 = 12.5+2.7-1.4 Mpc/h (comoving) and gamma = 1.68+0.14-0.30. The HI absorption measured around quasars exceeds that of any previously studied population, consistent with quasars being hosted by massive dark matter halos Mhalo~10^12.5 Msun at z~2.5. The environments of these massive halos are highly biased towards producing optically thick gas, and may even dominate the cosmic abundance of Lyman limit systems and hence th...

  19. A Catalog of Broad Absorption Line Quasars from the Sloan Digital Sky Survey Third Data Release

    CERN Document Server

    Trump, J R; Brinkman, J; Fan, X; Hall, P B; Kleinman, S J; Knapp, G R; Nitta, A; Reichard, T A; Richards, G T; Schneider, D P; Vanden Berk, Daniel E; Anderson, Scott F.; Berk, Daniel E. Vanden; Fan, Xiaohui; Hall, Patrick B.; Knapp, Gillian R.; Nitta, Atsuko; Reichard, Timothy A.; Richards, Gordon T.; Schneider, Donald P.; Trump, Jonathan R.

    2006-01-01

    We present a total of 4784 unique broad absorption line quasars from the Sloan Digital Sky Survey Third Data Release. An automated algorithm was used to match a continuum to each quasar and to identify regions of flux at least 10% below the continuum over a velocity range of at least 1000 km/s in the CIV and MgII absorption regions. The model continuum was selected as the best-fit match from a set of template quasar spectra binned in luminosity, emission line width, and redshift, with the power-law spectral index and amount of dust reddening as additional free parameters. We characterize our sample through the traditional ``balnicity'' index and a revised absorption index, as well as through parameters such as the width, outflow velocity, fractional depth and number of troughs. From a sample of 16883 quasars at 1.7 \\le z \\le 4.38, we identify 4386 (26.0%) quasars with broad CIV absorption, of which 1756 (10.4%) satisfy traditional selection criteria. From a sample of 34973 quasars at 0.5 \\le z \\le 2.15, we id...

  20. BROAD ABSORPTION LINE DISAPPEARANCE ON MULTI-YEAR TIMESCALES IN A LARGE QUASAR SAMPLE

    Energy Technology Data Exchange (ETDEWEB)

    Filiz Ak, N.; Brandt, W. N.; Schneider, D. P. [Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States); Hall, P. B. [Department of Physics and Astronomy, York University, 4700 Keele St., Toronto, Ontario M3J 1P3 (Canada); Anderson, S. F.; Gibson, R. R. [Astronomy Department, University of Washington, Seattle, WA 98195 (United States); Lundgren, B. F. [Department of Physics, Yale University, New Haven, CT 06511 (United States); Myers, A. D. [Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071 (United States); Petitjean, P. [Institut d' Astrophysique de Paris, Universite Paris 6, F-75014, Paris (France); Ross, Nicholas P. [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 92420 (United States); Shen Yue [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS-51, Cambridge, MA 02138 (United States); York, D. G. [Department of Astronomy and Astrophysics, and Enrico Fermi Institute, University of Chicago, 5640 S. Ellis Ave., Chicago, IL 60637 (United States); Bizyaev, D.; Brinkmann, J.; Malanushenko, E.; Oravetz, D. J.; Pan, K.; Simmons, A. E. [Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349-0059 (United States); Weaver, B. A., E-mail: nfilizak@astro.psu.edu [Center for Cosmology and Particle Physics, New York University, New York, NY 10003 (United States)

    2012-10-01

    We present 21 examples of C IV broad absorption line (BAL) trough disappearance in 19 quasars selected from systematic multi-epoch observations of 582 bright BAL quasars (1.9 < z < 4.5) by the Sloan Digital Sky Survey-I/II (SDSS-I/II) and SDSS-III. The observations span 1.1-3.9 yr rest-frame timescales, longer than have been sampled in many previous BAL variability studies. On these timescales, Almost-Equal-To 2.3% of C IV BAL troughs disappear and Almost-Equal-To 3.3% of BAL quasars show a disappearing trough. These observed frequencies suggest that many C IV BAL absorbers spend on average at most a century along our line of sight to their quasar. Ten of the 19 BAL quasars showing C IV BAL disappearance have apparently transformed from BAL to non-BAL quasars; these are the first reported examples of such transformations. The BAL troughs that disappear tend to be those with small-to-moderate equivalent widths, relatively shallow depths, and high outflow velocities. Other non-disappearing C IV BALs in those nine objects having multiple troughs tend to weaken when one of them disappears, indicating a connection between the disappearing and non-disappearing troughs, even for velocity separations as large as 10,000-15,000 km s{sup -1}. We discuss possible origins of this connection including disk-wind rotation and changes in shielding gas.

  1. Is the Long-Term Persistency of Circular Polarisation due to the Constant Helicity of the Magnetic Fields in Rotating Quasar Engines?

    OpenAIRE

    Ensslin, Torsten A.

    2003-01-01

    Many compact radio sources like quasars, blazars, radio galaxies, and micro-quasars emit circular polarisation (CP) with surprising temporal persistent handedness. We propose that the CP is caused by Faraday conversion of linear polarisation synchrotron light which propagates along a line-of-sight through helical magnetic fields. Jet outflows from radio galaxies should have the required magnetic helicity in the emission region due to the magnetic torque of the accretion disc. Also advection d...

  2. Outflowing atomic and molecular gas at z ~ 0.67 towards 1504 + 377

    Science.gov (United States)

    Kanekar, Nissim; Chengalur, Jayaram N.

    2008-02-01

    We report the detection of OH 1667-MHz and wide HI 21-cm absorption at z ~ 0.67 towards the red quasar 1504 + 377, with the Green Bank Telescope and the Giant Metrewave Radio Telescope. The HI 21-cm absorption extends over a velocity range of ~600kms-1 blueward of the quasar redshift (z = 0.674), with the new OH 1667-MHz absorption component at ~-430kms-1, nearly coincident with earlier detections of millimetre-wave absorption at z ~ 0.6715. The atomic and molecular absorption appear to arise from a fast gas outflow from the quasar, with a mass outflow rate and a molecular hydrogen fraction . The radio structure of 1504 + 377 is consistent with the outflow arising as a result of a jet-cloud interaction, followed by rapid cooling of the cloud material. The observed ratio of HCO+ and OH column densities is ~20 times higher than typical values in Galactic and high-z absorbers. This could arise because of small-scale structure in the outflowing gas on sub-parsec scales, which would also explain the observed variability in the HI 21-cm line.

  3. The Road to Quasars

    CERN Document Server

    Kellermann, K I

    2014-01-01

    Although the extragalactic nature of 3C 48 and other quasi stellar radio sources was discussed as early as 1960 by John Bolton and others, it was rejected largely because of preconceived ideas about what appeared to be unrealistically high radio and optical luminosities. Not until the 1962 occultations of the strong radio source 3C 273 at Parkes, which led Maarten Schmidt to identify 3C 273 with an apparent stellar object at a redshift of 0.16, was the true nature understood. Successive radio and optical measurements quickly led to the identification of other quasars with increasingly large redshifts and the general, although for some decades not universal, acceptance of quasars as the very luminous nuclei of galaxies. Curiously, 3C 273, which is one of the strongest extragalactic sources in the sky, was first cataloged in 1959 and the magnitude 13 optical counterpart was observed at least as early as 1887. Since 1960, much fainter optical counterparts were being routinely identified using accurate radio inte...

  4. Dusty Quasars at High Redshifts

    CERN Document Server

    Weedman, Daniel

    2016-01-01

    A population of quasars at z ~ 2 is determined based on dust luminosities vLv(7.8 um) that includes unobscured, partially obscured, and obscured quasars. Quasars are classified by the ratio vLv(0.25 um)/vLv(7.8 um) = UV/IR, assumed to measure obscuration of UV luminosity by the dust which produces IR luminosity. Quasar counts at rest frame 7.8 um are determined for quasars in the Bootes field of the NOAO Deep Wide Field Survey using 24 um sources with optical redshifts from the AGN and Galaxy Evolution Survey (AGES) or infrared redshifts from the Spitzer Infrared Spectrograph. Spectral energy distributions are extended to far infrared wavelengths using observations from the Herschel Space Observatory Spectral and Photometric Imaging Receiver (SPIRE), and new SPIRE photometry is presented for 77 high redshift quasars from the Sloan Digital Sky Survey. It is found that unobscured and obscured quasars have similar space densities at rest frame 7.8 um, but the ratio Lv(100 um)/Lv(7.8 um) is about three times high...

  5. Disks and Outflows

    Science.gov (United States)

    Rodriguez, L. F.

    2002-05-01

    The presence of disks and outflows characterizes the earliest stages of stellar evolution. I will review recent results that exemplify how the radio observations have become powerful tools in the study of these extremely young objects. Binarity and multiplicity seem to be factors that we are only starting to understand. Outflows are now seen as laboratories for the chemistry of shocked regions. Finally, the efforts to extend the paradigm for low-mass stellar formation to more massive protostars can be tested critically in the radio wavelengths. I acknowledge the support from CONACyT, Mexico.

  6. Vanishing Absorption and Blueshifted Emission in FeLoBAL Quasars

    CERN Document Server

    Rafiee, Alireza; Hall, Patrick B; Galati, Natalee; Rogerson, Jesse; Ameri, Abtin

    2016-01-01

    We study the dramatic decrease in iron absorption strength in the iron low-ionization broad absorption line quasar SDSS J084133.15+200525.8. We report on the continued weakening of absorption in the prototype of this class of variable broad absorption line quasar, FBQS J140806.2+305448. We also report a third example of this class, SDSS J123103.70+392903.6; unlike the other two examples, it has undergone an increase in observed continuum brightness (at 3000~\\AA\\ rest-frame) as well as a decrease in iron absorption strength. These changes could be caused by absorber transverse motion or by ionization variability. We note that the \\mgii\\ and UV \\feii\\ lines in several FeLoBAL quasars are blueshifted by thousands of \\kms\\ relative to the \\Hb\\ emission line peak. We suggest that such emission arises in the outflowing winds normally seen only in absorption.

  7. Discovery of an X-ray Violently Variable Broad Absorption Line Quasar

    Science.gov (United States)

    Ghosh, Kajal K.; Gutierrez, Carlos M.; Punsly, Brian; Chevallier, Loic; Goncalves, Anabela C.

    2006-01-01

    In this letter, we report on a quasar that is violently variable in the X-rays, XVV. It is also a broad absorption line quasar (BALQSO) that exhibits both high ionization and low ionization UV absorption lines (LoBALQSO). It is very luminous in the X-rays (approximately 10(exp 46) ergs s(sup -l) over the entire X-ray band). Surprisingly, this does not over ionize the LoBAL outflow. The X-rays vary by a factor of two within minutes in the quasar rest frame, which is shorter than 1/30 of the light travel time across a scale length equal to the black hole radius. We concluded that the X-rays are produced in a relativistic jet beamed toward earth in which variations in the Doppler enhancement produce the XVV behavior.

  8. Testing Quasar Unification: Radiative Transfer in Clumpy Winds

    CERN Document Server

    Matthews, James H; Long, Knox S; Sim, Stuart A; Higginbottom, Nick; Mangham, Sam W

    2016-01-01

    Various unification schemes interpret the complex phenomenology of quasars and luminous active galactic nuclei (AGN) in terms of a simple picture involving a central black hole, an accretion disc and an associated outflow. Here, we continue our tests of this paradigm by comparing quasar spectra to synthetic spectra of biconical disc wind models, produced with our state-of-the-art Monte Carlo radiative transfer code. Previously, we have shown that we could produce synthetic spectra resembling those of observed broad absorption line (BAL) quasars, but only if the X-ray luminosity was limited to $10^{43}$ erg s$^{-1}$. Here, we introduce a simple treatment of clumping, and find that a filling factor of $\\sim0.01$ moderates the ionization state sufficiently for BAL features to form in the rest-frame UV at more realistic X-ray luminosities. Our fiducial model shows good agreement with AGN X-ray properties and the wind produces strong line emission in, e.g., Ly \\alpha\\ and CIV 1550\\AA\\ at low inclinations. At high ...

  9. Optical Variability Properties of Mini-BAL and NAL Quasars

    CERN Document Server

    Horiuchi, Takashi; Morokuma, Tomoki; Koyamada, Suzuka; Takahashi, Kazuma; Wada, Hisashi

    2016-01-01

    While narrow absorption lines (NALs) are relatively stable, broad absorption lines (BALs) and mini-BAL systems usually show violent time variability within a few years via a mechanism that is not yet understood. In this study, we examine variable ionization state (VIS) scenario as a plausible mechanism, as previously suspected. Over three years, we performed photometric monitoring observations of four mini-BAL and five NAL quasars at $z_{\\rm em}$ $\\sim$ 2.0 - 3.1 using the 105 cm Kiso Schmidt Telescope in $u$, $g$, and $i$-bands. We also performed spectroscopic monitoring observation of one of our mini-BAL quasar (HS1603+3820) using the 188-cm Okayama Telescope over the same period as the photometric observations. Our main results are as follows: (1) Structure function (SF) analysis revealed that the quasar UV flux variability over three years was not large enough to support the VIS scenario, unless the ionization condition of outflow gas is very low. (2) There was no crucial difference between the SFs of min...

  10. Mediterranean Outflow Mixing Dynamics

    Science.gov (United States)

    1993-02-01

    tugal. G. Parrnlla is at Instituto EspaWol Oceanografia , Fig. 2A. [Adapted from (36)] (C) The maximum observed velocity of outflow currents in the eastern...its sur- Oceanografia Fisica del Estrecho de Gibraltar, J. of Mediterranean water that we observed at the roundings (34) and retains its chemical L

  11. GALAXY OUTFLOWS WITHOUT SUPERNOVAE

    Energy Technology Data Exchange (ETDEWEB)

    Sur, Sharanya [Indian Institute of Astrophysics, 2nd Block, Koramangala, Bangalore 560034 (India); Scannapieco, Evan [School of Earth and Space Exploration, Arizona State University, P.O. Box 876004, Tempe-85287 (United States); Ostriker, Eve C., E-mail: sharanya.sur@iiap.res.in, E-mail: sharanya.sur@asu.edu [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)

    2016-02-10

    High surface density, rapidly star-forming galaxies are observed to have ≈50–100 km s{sup −1} line of sight velocity dispersions, which are much higher than expected from supernova driving alone, but may arise from large-scale gravitational instabilities. Using three-dimensional simulations of local regions of the interstellar medium, we explore the impact of high velocity dispersions that arise from these disk instabilities. Parametrizing disks by their surface densities and epicyclic frequencies, we conduct a series of simulations that probe a broad range of conditions. Turbulence is driven purely horizontally and on large scales, neglecting any energy input from supernovae. We find that such motions lead to strong global outflows in the highly compact disks that were common at high redshifts, but weak or negligible mass loss in the more diffuse disks that are prevalent today. Substantial outflows are generated if the one-dimensional horizontal velocity dispersion exceeds ≈35 km s{sup −1}, as occurs in the dense disks that have star-formation rate (SFR) densities above ≈0.1 M{sub ⊙} yr{sup −1} kpc{sup −2}. These outflows are triggered by a thermal runaway, arising from the inefficient cooling of hot material coupled with successive heating from turbulent driving. Thus, even in the absence of stellar feedback, a critical value of the SFR density for outflow generation can arise due to a turbulent heating instability. This suggests that in strongly self-gravitating disks, outflows may be enhanced by, but need not caused by, energy input from supernovae.

  12. On the Formation of Molecular Clumps in QSO Outflows

    Science.gov (United States)

    Ferrara, A.; Scannapieco, E.

    2016-12-01

    We study the origin of the cold molecular clumps in quasar outflows, recently detected in CO and HCN emission. We first describe the physical properties of such radiation-driven outflows and show that a transition from a momentum- to an energy-driven flow must occur at a radial distance of R≈ 0.25 {kpc}. During this transition, the shell of swept-up material fragments due to Rayleigh-Taylor instabilities, but these clumps contain little mass and are likely to be rapidly ablated by the hot gas in which they are immersed. We then explore an alternative scenario in which clumps form from thermal instabilities at R≳ 1 {kpc}, possibly containing enough dust to catalyze molecule formation. We investigate this process with 3D two-fluid (gas+dust) numerical simulations of a kpc3 patch of the outflow, including atomic and dust cooling, thermal conduction, dust sputtering, and photoionization from the QSO radiation field. In all cases, dust grains are rapidly destroyed in ≈ {10}4 years; and while some cold clumps form at later times, they are present only as transient features, which disappear as cooling becomes more widespread. In fact, we only find a stable two-phase medium with dense clumps if we artificially enhance the QSO radiation field by a factor of 100. This result, together with the complete destruction of dust grains, renders the interpretation of molecular outflows a very challenging problem.

  13. MAJOR CONTRIBUTOR TO AGN FEEDBACK: VLT X-SHOOTER OBSERVATIONS OF S IV BALQSO OUTFLOWS

    Energy Technology Data Exchange (ETDEWEB)

    Borguet, Benoit C. J.; Arav, Nahum; Edmonds, Doug; Chamberlain, Carter [Department of Physics, Virginia Tech, Blacksburg, VA 24061 (United States); Benn, Chris, E-mail: b.borguet@alumni.ulg.ac.be [Isaac Newton Group, Apartado 321, E-38700 Santa Cruz de La Palma (Spain)

    2013-01-01

    We present the most energetic BALQSO outflow measured to date, with a kinetic luminosity of at least 10{sup 46} erg s{sup -1}, which is 5% of the bolometric luminosity of this high Eddington ratio quasar. The associated mass-flow rate is 400 solar masses per year. Such kinetic luminosity and mass-flow rate should provide strong active galactic nucleus feedback effects. The outflow is located at about 300 pc from the quasar and has a velocity of roughly 8000 km s{sup -1}. Our distance and energetic measurements are based in large part on the identification and measurement of S IV and S IV* broad absorption lines (BALs). The use of this high-ionization species allows us to generalize the result to the majority of high-ionization BALQSOs that are identified by their C IV absorption. We also report the energetics of two other outflows seen in another object using the same technique. The distances of all three outflows from the central source (100-2000 pc) suggest that we observe BAL troughs much farther away from the central source than the assumed acceleration region of these outflows (0.01-0.1 pc).

  14. Accurate spectroscopic redshift of the multiply lensed quasar PSOJ0147 from the Pan-STARRS survey

    Science.gov (United States)

    Lee, C.-H.

    2017-09-01

    Context. The gravitational lensing time delay method provides a one-step determination of the Hubble constant (H0) with an uncertainty level on par with the cosmic distance ladder method. However, to further investigate the nature of the dark energy, a H0 estimate down to 1% level is greatly needed. This requires dozens of strongly lensed quasars that are yet to be delivered by ongoing and forthcoming all-sky surveys. Aims: In this work we aim to determine the spectroscopic redshift of PSOJ0147, the first strongly lensed quasar candidate found in the Pan-STARRS survey. The main goal of our work is to derive an accurate redshift estimate of the background quasar for cosmography. Methods: To obtain timely spectroscopically follow-up, we took advantage of the fast-track service programme that is carried out by the Nordic Optical Telescope. Using a grism covering 3200-9600 Å, we identified prominent emission line features, such as Lyα, N V, O I, C II, Si IV, C IV, and [C III] in the spectra of the background quasar of the PSOJ0147 lens system. This enables us to determine accurately the redshift of the background quasar. Results: The spectrum of the background quasar exhibits prominent absorption features bluewards of the strong emission lines, such as Lyα, N V, and C IV. These blue absorption lines indicate that the background source is a broad absorption line (BAL) quasar. Unfortunately, the BAL features hamper an accurate determination of redshift using the above-mentioned strong emission lines. Nevertheless, we are able to determine a redshift of 2.341 ± 0.001 from three of the four lensed quasar images with the clean forbidden line [C III]. In addition, we also derive a maximum outflow velocity of 9800 km s-1 with the broad absorption features bluewards of the C IV emission line. This value of maximum outflow velocity is in good agreement with other BAL quasars.

  15. Ultra-fast outflows (aka UFOs) in AGNs and their relevance for feedback

    Science.gov (United States)

    Cappi, Massimo; Tombesi, F.; Giustini, M.; Dadina, M.; Braito, V.; Kaastra, J.; Reeves, J.; Chartas, G.; Gaspari, M.; Vignali, C.; Gofford, J.; Lanzuisi, G.

    2012-09-01

    During the last decade, several observational evidences have been accumulated for the existence of massive, high velocity winds/outflows (aka UFOs) in nearby AGNs and, possibly, distant quasars. I will review here such evidences, present some of the latest results in this field, and discuss the relevance of UFOs for both understanding the physics of accretion/ejection flows on supermassive black holes, and for quantifying the amount of AGN feedback.

  16. Galaxy Outflows Without Supernovae

    CERN Document Server

    Sur, Sharanya; Ostriker, Eve C

    2016-01-01

    High surface density, rapidly star-forming galaxies are observed to have $\\approx 50-100\\,{\\rm km\\,s^{-1}}$ line-of-sight velocity dispersions, which are much higher than expected from supernova driving alone, but may arise from large-scale gravitational instabilities. Using three-dimensional simulations of local regions of the interstellar medium, we explore the impact of high velocity dispersions that arise from these disk instabilities. Parametrizing disks by their surface densities and epicyclic frequencies, we conduct a series of simulations that probe a broad range of conditions. Turbulence is driven purely horizontally and on large scales, neglecting any energy input from supernovae. We find that such motions lead to strong global outflows in the highly-compact disks that were common at high redshifts, but weak or negligible mass loss in the more diffuse disks that are prevalent today. Substantial outflows are generated if the one-dimensional horizontal velocity dispersion exceeds $\\approx 35\\,{\\rm km\\...

  17. VLBI Detections of Parsec-Scale Nonthermal Jets in Radio-Loud Broad Absorption Line Quasars

    CERN Document Server

    Doi, Akihiro; Kono, Yusuke; Oyama, Tomoaki; Fujisawa, Kenta; Takaba, Hiroshi; Sudou, Hiroshi; Wakamatsu, Ken-ichi; Yamauchi, Aya; Murata, Yasuhiro; Mochizuki, Nanako; Wajima, Kiyoaki; Omodaka, Toshihiro; Nagayama, Takumi; Nakai, Naomasa; Sorai, Kazuo; Kawai, Eiji; Sekido, Mamoru; Koyama, Yasuhiro; Asano, Shoichiro; Uose, Hisao

    2009-01-01

    We conducted radio detection observations at 8.4 GHz for 22 radio-loud broad absorption line (BAL) quasars, selected from the Sloan Digital Sky Survey (SDSS) Third Data Release, by a very-long-baseline interferometry (VLBI) technique. The VLBI instrument we used was developed by the Optically ConnecTed Array for VLBI Exploration project (OCTAVE), which is operated as a subarray of the Japanese VLBI Network (JVN). We aimed at selecting BAL quasars with nonthermal jets suitable for measuring their orientation angles and ages by subsequent detailed VLBI imaging studies to evaluate two controversial issues of whether BAL quasars are viewed nearly edge-on, and of whether BAL quasars are in a short-lived evolutionary phase of quasar population. We detected 20 out of 22 sources using the OCTAVE baselines, implying brightness temperatures greater than 10^5 K, which presumably come from nonthermal jets. Hence, BAL outflows and nonthermal jets can be generated simultaneously in these central engines. We also found four...

  18. FeLoBAL Outflow Variability Constraints from Multi-Year Observations

    CERN Document Server

    McGraw, Sean M; Hamann, Frederick W; Capellupo, Daniel M; Gallagher, Sarah C; Brandt, William N

    2013-01-01

    The physical properties and dynamical behavior of Broad Absorption Line (BAL) outflows are crucial themes in understanding the connections between galactic centers and their hosts. FeLoBALs (identified with the presence of low-ionization Fe II BALs) are a peculiar class of quasar outflows that constitute approximately 1% of the BAL population. With their large column densities and apparent outflow kinetic luminosities, FeLoBALs appear to be exceptionally powerful and are strong candidates for feedback in galaxy evolution. We conducted variability studies of 12 FeLoBAL quasars with emission redshifts between 0.69 and 1.93, spanning both weekly and multi-year timescales in the quasar's rest frame. We detected absorption-line variability from low-ionization species (Fe II, Mg II) in four of our objects, with which we established a representative upper limit for the distance of the absorber from the supermassive black hole (SMBH) to be approximately 20 parsecs. Our goals are to understand the mechanisms producing...

  19. Outflowing atomic and molecular gas at $z \\sim 0.67$ towards 1504+377

    CERN Document Server

    Kanekar, Nissim

    2007-01-01

    We report the detection of OH 1667 MHz and wide HI 21cm absorption at $z \\sim 0.67$ towards the red quasar 1504+377, with the Green Bank Telescope and the Giant Metrewave Radio Telescope. The HI 21cm absorption extends over a velocity range of $\\sim 600$ km/s blueward of the quasar redshift ($z=0.674$), with the new OH 1667 MHz absorption component at $\\sim -430$ \\kms, nearly coincident with earlier detections of mm-wave absorption at $z \\sim 0.6715$. The atomic and molecular absorption appear to arise from a fast gas outflow from the quasar, with a mass outflow rate ${\\dot M} \\sim 12 M_\\odot$ yr$^{-1}$ and a molecular hydrogen fraction $f_{\\rm H_2} \\equiv (N_{\\rm H_2}/N_{\\rm HI}) \\sim 0.2$. The radio structure of 1504+377 is consistent with the outflow arising due to a jet-cloud interaction, followed by rapid cooling of the cloud material. The observed ratio of HCO$^+$ to OH column densities is $\\sim 20$ times higher than typical values in Galactic and high-$z$ absorbers. This could arise due to small-scale ...

  20. Extreme star formation events in quasar hosts over 0.5 < z < 4

    Science.gov (United States)

    Pitchford, L. K.; Hatziminaoglou, E.; Feltre, A.; Farrah, D.; Clarke, C.; Harris, K. A.; Hurley, P.; Oliver, S.; Page, M.; Wang, L.

    2016-11-01

    We explore the relationship between active galactic nuclei (AGN) and star formation in a sample of 513 optically luminous type 1 quasars up to redshifts of ˜4 hosting extremely high star formation rates (SFRs). The quasars are selected to be individually detected by the Herschel SPIRE instrument at >3σ at 250 μm, leading to typical SFRs of order of 1000 M⊙ yr-1. We find the average SFRs to increase by almost a factor 10 from z ˜ 0.5 to z ˜ 3, mirroring the rise in the comoving SFR density over the same epoch. However, we find that the SFRs remain approximately constant with increasing accretion luminosity for accretion luminosities above 1012 L⊙. We also find that the SFRs do not correlate with black hole mass. Both of these results are most plausibly explained by the existence of a self-regulation process by the starburst at high SFRs, which controls SFRs on time-scales comparable to or shorter than the AGN or starburst duty cycles. We additionally find that SFRs do not depend on Eddington ratio at any redshift, consistent with no relation between SFR and black hole growth rate per unit black hole mass. Finally, we find that high-ionization broad absorption line (HiBAL) quasars have indistinguishable far-infrared properties to those of classical quasars, consistent with HiBAL quasars being normal quasars observed along a particular line of sight, with the outflows in HiBAL quasars not having any measurable effect on the star formation in their hosts.

  1. Quasar Structure from Microlensing in Gravitationally Lensed Quasars

    Science.gov (United States)

    Morgan, Christopher W.

    2007-12-01

    I investigate microlensing in gravitationally lensed quasars and discuss the use of its signal to probe quasar structure on small angular scales. I describe our lensed quasar optical monitoring program and RETROCAM, the optical camera I built for the 2.4m Hiltner telescope to monitor lensed quasars. I use the microlensing variability observed in 11 gravitationally lensed quasars to show that the accretion disk size at 2500Å is related to the black hole mass by log(R2500/cm) = (15.70±0.16) + (0.64±0.18)log(MBH/109M⊙). This scaling is consistent with the expectation from thin disk theory (R ∝ MBH2/3), but it implies that black holes radiate with relatively low efficiency, log(η) = -1.54±0.36 + log(L/LE) where η=L/(Mdotc2). With one exception, these sizes are larger by a factor of 4 than the size needed to produce the observed 0.8µm quasar flux by thermal radiation from a thin disk with the same T ∝ R-3/4 temperature profile. More sophisticated disk models are clearly required, particularly as our continuing observations improve the precision of the measurements and yield estimates of the scaling with wavelength and accretion rate. This research made extensive use of a Beowulf computer cluster obtained through the Cluster Ohio program of the Ohio Supercomputer Center. Support for program HST-GO-9744 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS-5-26666.

  2. Dressing a naked quasar: star formation and AGN feedback in HE0450-2958

    CERN Document Server

    Klamer, I; Ekers, R; Middelberg, E; Klamer, Ilana; Papadopoulos, Padelis; Ekers, Ron; Middelberg, Enno

    2007-01-01

    We present Australia Telescope Compact Array radio continuum observations of the quasar/galaxy system HE0450-2958. An asymetric triple linear morphology is observed, with the central radio component coincident with the quasar core and a second radio component associated with a companion galaxy at a projected distance of 7kpc from the quasar. The system obeys the far-infrared to radio continuum correlation, implying the radio emission is energetically dominated by star formation activity. However, there is undoubtedly some contribution to the overall radio emission from a low-luminosity AGN core and a pair of radio lobes. Long baseline radio interferometric observations of the quasar core place a 3sigma upper limit of 0.6mJy at 1400MHz on the AGN contribution to the quasar's radio emission; less than 30% of the total. The remaining 70% of the radio emission from the quasar is associated with star formation activity and provides the first direct evidence for the quasar's host galaxy. A re-anlaysis of the VLT sp...

  3. Radio Through X-ray Spectral Energy Distributions of 38 Broad Absorption Line Quasars

    CERN Document Server

    Gallagher, S C; Brandt, W N; Egami, E; Hines, D C; Priddey, R S

    2007-01-01

    We have compiled the largest sample of multiwavelength spectral energy distributions (SEDs) of Broad Absorption Line (BAL) quasars to date, from the radio to the X-ray. We present new Spitzer MIPS (24, 70, and 160 micron) observations of 38 BAL quasars in addition to data from the literature and public archives. In general, the mid-infrared properties of BAL quasars are consistent with those of non-BAL quasars of comparable luminosity. In particular, the optical-to-mid-infrared luminosity ratios of the two populations are indistinguishable. We also measure or place upper limits on the contribution of star formation to the far-infrared power. Of 22 (57%) upper limits, seven quasars have sufficiently sensitive constraints to conclude that star formation likely contributes little (<20%) to their far-infrared power. The 17 BAL quasars (45%) with detected excess far-infrared emission likely host hyperluminous starbursts with L_fir,SF=10^{13-14} L_sun. Mid-infrared through X-ray composite BAL quasar SEDs are pre...

  4. A Simple Disk Wind Model for Broad Absorption Line Quasars

    CERN Document Server

    Higginbottom, N; Long, K S; Sim, S A; Matthews, J H

    2013-01-01

    Approximately 20% of quasi-stellar objects (QSOs) exhibit broad, blue-shifted absorption lines in their ultraviolet spectra. Such features provide clear evidence for significant outflows from these systems, most likely in the form of accretion disk winds. These winds may represent the "quasar" mode of feedback that is often invoked in galaxy formation/evolution models, and they are also key to unification scenarios for active galactic nuclei (AGN) and QSOs. To test these ideas, we construct a simple benchmark model of an equatorial, biconical accretion disk wind in a QSO and use a Monte Carlo ionization/radiative transfer code to calculate the ultraviolet spectra as a function of viewing angle. We find that for plausible outflow parameters, sightlines looking directly into the wind cone do produce broad, blue-shifted absorption features in the transitions typically seen in broad absorption line QSOs. However, our benchmark model is intrinsically X-ray weak in order to prevent overionization of the outflow, an...

  5. High redshift quasars monitoring campaign

    Science.gov (United States)

    Botti, Ismael; Lira, Paulina; Martinez, Jorge; Netzer, Hagai; Kaspi, Shai

    2014-07-01

    We present an update of the monitoring campaign we have undertaken to probe the most massive black holes in powerful quasars at high redshift through the reverberation mapping technique. Once this campaign has finished, we will be able to directly measure broad line region (BLR) sizes of quasars at z ~ 2-3, improving dramatically the BLR size-luminosity relation, and therefore, black hole mass estimates based on this relationship. So far, we have identified a dozen highly variable sources suitable for future cross-correlation analysis and reverberation measurements.

  6. Quasar Rain: The Broad Emission Line Region as Condensations in the Warm Accretion Disk Wind

    Science.gov (United States)

    Elvis, Martin

    2017-09-01

    The origin of the broad emission line region (BELR) in quasars and active galactic nuclei is still unclear. I propose that condensations form in the warm, radiation-pressure-driven, accretion disk wind of quasars creating the BEL clouds and uniting them with the other two manifestations of cool (∼104 K) gas in quasars, the low ionization phase of the warm absorbers (WAs) and the clouds causing X-ray eclipses. The cool clouds will condense quickly (days to years), before the WA outflows reach escape velocity (which takes months to centuries). Cool clouds form in equilibrium with the warm phase of the wind because the rapidly varying X-ray quasar continuum changes the force multiplier, causing pressure waves to move gas into stable locations in pressure–temperature space. The narrow range of two-phase equilibrium densities may explain the (luminosity){}1/2 scaling of the BELR size, while the scaling of cloud formation timescales could produce the Baldwin effect. These dense clouds have force multipliers of order unity and so cannot be accelerated to escape velocity. They fall back on a dynamical timescale (months to centuries), producing an inflow that rains down toward the central black hole. As they soon move at Mach ∼10–100 with respect to the WA outflow, these “raindrops” will be rapidly destroyed within months. This rain of clouds may produce the elliptical BELR orbits implied by velocity-resolved reverberation mapping in some objects and can explain the opening angle and destruction timescale of the narrow “cometary” tails of the clouds seen in X-ray eclipse observations. Some consequences and challenges of this “quasar rain” model are presented, along with several avenues for theoretical investigation.

  7. Searching for Brown Dwarf Outflows

    CERN Document Server

    Whelan, E T; Bacciotti, F; Randich, S; Natta, A

    2009-01-01

    As outflow activity in low mass protostars is strongly connected to ac- cretion it is reasonable to expect accreting brown dwarfs to also be driving out- flows. In the last three years we have searched for brown dwarf outflows using high quality optical spectra obtained with UVES on the VLT and the technique of spectro-astrometry. To date five brown dwarf outflows have been discovered. Here the method is discussed and the results to date outlined.

  8. On the Formation of Molecular Clumps in QSO Outflows

    CERN Document Server

    Ferrara, Andrea

    2016-01-01

    We study the origin of the cold molecular clumps in quasar outflows, recently detected in CO and HCN emission. We first describe the physical properties of such radiation-driven outflows and show that a transition from a momentum- to an energy-driven flow must occur at a radial distance of R ~ 0.25 kpc. During this transition, the shell of swept up material fragments due to Rayleigh-Taylor instabilities, but these clumps contain little mass and are likely to be rapidly ablated by the hot gas in which they are immersed. We then explore an alternative scenario in which clumps form from thermal instabilities at R >~ 1 kpc, possibly containing enough dust to catalyze molecule formation. We investigate this processes with 3D two-fluid (gas+dust) numerical simulations of a kpc^3 patch of the outflow, including atomic and dust cooling, thermal conduction, dust sputtering, and photoionization from the QSO radiation field. In all cases, dust grains are rapidly destroyed in ~10,000 years; and while some cold clumps for...

  9. Spin properties of supermassive black holes with powerful outflows

    Science.gov (United States)

    Daly, Ruth. A.

    2016-05-01

    Relationships between beam power and accretion disc luminosity are studied for a sample of 55 high excitation radio galaxies (HERG), 13 low excitation radio galaxies (LERG), and 29 radio loud quasars (RLQ) with powerful outflows. The ratio of beam power to disc luminosity tends to be high for LERG, low for RLQ, and spans the full range of values for HERG. Writing general expressions for the disc luminosity and beam power and applying the empirically determined relationships allows a function that parametrizes the spins of the holes to be estimated. Interestingly, one of the solutions that is consistent with the data has a functional form that is remarkably similar to that expected in the generalized Blandford-Znajek model with a magnetic field that is similar in form to that expected in magnetically arrested disk (MAD) and advection-dominated accretion flow (ADAF) models. Values of the spin function, obtained independent of specific outflow models, suggest that spin and active galactic nucleus type are not related for these types of sources. The spin function can be used to solve for black hole spin in the context of particular outflow models, and one example is provided.

  10. Evolution of active region outflows throughout an active region lifetime

    Science.gov (United States)

    Zangrilli, L.; Poletto, G.

    2016-10-01

    Context. We have shown previously that SOHO/UVCS data allow us to detect active region (AR) outflows at coronal altitudes higher than those reached by other instrumentation. These outflows are thought to be a component of the slow solar wind. Aims: Our purpose is to study the evolution of the outflows in the intermediate corona from AR 8100, from the time the AR first forms until it dissolves, after several transits at the solar limb. Methods: Data acquired by SOHO/UVCS at the time of the AR limb transits, at medium latitudes and at altitudes ranging from 1.5 to 2.3 R⊙, were used to infer the physical properties of the outflows through the AR evolution. To this end, we applied the Doppler dimming technique to UVCS spectra. These spectra include the H i Lyα line and the O vi doublet lines at 1031.9 and 1037.6 Å. Results: Plasma speeds and electron densities of the outflows were inferred over several rotations of the Sun. AR outflows are present in the newly born AR and persist throughout the entire AR life. Moreover, we found two types of outflows at different latitudes, both possibly originating in the same negative polarity area of the AR. We also analyzed the behavior of the Si xii 520 Å line along the UVCS slit in an attempt to reveal changes in the Si abundance when different regions are traversed. Although we found some evidence for a Si enrichment in the AR outflows, alternative interpretations are also plausible. Conclusions: Our results demonstrate that outflows from ARs are detectable in the intermediate corona throughout the whole AR lifetime. This confirms that outflows contribute to the slow wind.

  11. Extremely Red Quasars in BOSS

    CERN Document Server

    Hamann, Fred; Ross, Nicholas; Paris, Isabelle; Alexandroff, Rachael M; Villforth, Carolin; Richards, Gordon T; Herbst, Hanna; Brandt, W Niel; Cook, Ben; Denney, Kelly D; Greene, Jenny E; Schneider, Donald P; Strauss, Michael A

    2016-01-01

    Red quasars are candidate young objects in an early transition stage of massive galaxy evolution. Our team recently discovered a population of extremely red quasars (ERQs) in the Baryon Oscillation Spectroscopic Survey (BOSS) that has a suite of peculiar emission-line properties including large rest equivalent widths (REWs), unusual "wingless" line profiles, large NV/Lya, NV/CIV, SiIV/CIV and other flux ratios, and very broad and blueshifted [OIII] 5007. Here we present a new catalog of CIV and NV emission-line data for 216,188 BOSS quasars to characterize the ERQ line properties further. We show that they depend sharply on UV-to-mid-IR color, secondarily on REW(CIV), and not at all on luminosity or the Baldwin Effect. We identify a "core" sample of 97 ERQs with nearly uniform peculiar properties selected via i-W3 > 4.6 (AB) and REW(CIV) > 100 A at redshifts 2.0-3.4. A broader search finds 235 more red quasars with similar unusual characteristics. The core ERQs have median luminosity log L (ergs/s) ~ 47.1, sk...

  12. A simple disc wind model for broad absorption line quasars

    Science.gov (United States)

    Higginbottom, N.; Knigge, C.; Long, K. S.; Sim, S. A.; Matthews, J. H.

    2013-12-01

    Approximately 20 per cent of quasi-stellar objects (QSOs) exhibit broad, blue-shifted absorption lines in their ultraviolet spectra. Such features provide clear evidence for significant outflows from these systems, most likely in the form of accretion disc winds. These winds may represent the `quasar' mode of feedback that is often invoked in galaxy formation/evolution models, and they are also key to unification scenarios for active galactic nuclei (AGN) and QSOs. To test these ideas, we construct a simple benchmark model of an equatorial, biconical accretion disc wind in a QSO and use a Monte Carlo ionization/radiative transfer code to calculate the ultraviolet spectra as a function of viewing angle. We find that for plausible outflow parameters, sightlines looking directly into the wind cone do produce broad, blue-shifted absorption features in the transitions typically seen in broad absorption line (BAL) QSOs. However, our benchmark model is intrinsically X-ray weak in order to prevent overionization of the outflow, and the wind does not yet produce collisionally excited line emission at the level observed in non-BAL QSOs. As a first step towards addressing these shortcomings, we discuss the sensitivity of our results to changes in the assumed X-ray luminosity and mass-loss rate, Ṁwind. In the context of our adopted geometry, Ṁwind ˜ Ṁacc is required in order to produce significant BAL features. The kinetic luminosity and momentum carried by such outflows would be sufficient to provide significant feedback.

  13. Mean Spectral Energy Distributions and Bolometric Corrections for Luminous Quasars

    CERN Document Server

    Krawczyk, Coleman M; Mehta, Sajjan S; Vogeley, Michael S; Gallagher, S C; Leighly, Karen M; Ross, Nicholas P; Schneider, Donald P; 10.1088/0067-0049/206/1/4

    2013-01-01

    We explore the mid-infrared (mid-IR) through ultraviolet (UV) spectral energy distributions (SEDs) of 119,652 luminous broad-lined quasars with 0.0641.6; the latter is a possible indicator of the strength of the accretion disk wind, which is expected to be SED dependent. Luminosity-dependent mean SEDs show that, relative to the high-luminosity SED, low-luminosity SEDs exhibit a harder (bluer) far-UV spectral slope, a redder optical continuum, and less hot dust. Mean SEDs constructed instead as a function of UV emission line properties reveal changes that are consistent with known Principal Component Analysis (PCA) trends. A potentially important contribution to the bolometric correction is the unseen extream-UV (EUV) continuum. Our work suggests that lower-luminosity quasars and/or quasars with disk-dominated broad emission lines may require an extra continuum component in the EUV that is not present (or much weaker) in high-luminosity quasars with strong accretion disk winds. As such, we consider four possib...

  14. The LBT/WISSH quasar survey: revealing powerful winds in the most luminous AGN

    Science.gov (United States)

    Vietri, Giustina

    2017-01-01

    The systematic, multi-frequency investigation of hyper-luminous quasars shining at the golden epoch of AGN activity offers the unique opportunity of studying the power and the effect of AGN feedback at its extreme.The WISE/SDSS selected hyper-luminous (WISSH) quasar survey is an extensive multi-band observing program (from millimeter wavelengths to hard X rays) designed to accurately probe the role of nuclear activity in SMBH-galaxy self-regulated growth via extended outflows.Our on-going project aims at constraining both AGN and host galaxy ISM and star-formation properties in a large sample of ~ 90 broad-line quasars at the brightest end of the AGN luminosity function (L_bol > 1e14 L_sun), and at the peak of their number density (z ~ 2.5 - 3.5).I will review the most important results of the near-IR spectroscopic follow-up of WISSH quasars (available for ~40% of the total sample) performed with the LUCI at LBT. These observations were carried out to obtain a reliable Hbeta-based estimate of the SMBH masses and a census of the ionized outflows in these hyper-luminous quasars.We found that WISSH AGN are typically powered by highly accreting (0.3-3 Ledd), ten billion solar masses SMBHs, demonstrating that WISSH provides a simple and valuable tool to complete the census of the extreme SMBH population in the universe.We also succeeded in discovering [OIII] emission lines with a broad, skewed profile and exceptional luminosities (> 6e44 erg/s), tracing very powerful ionized outflows (up to ~4% of L_bol) in ~30% of the sample.Remarkably, the remaining 70% of quasars lacks [OIII] emission but shows strong winds traced by 3,000-8,000 km/s blueshifts of the high-ionization (CIV) with respect to low-ionization (Hbeta) broad emission lines, revealing strong radiatively driven winds that dominate the BLR kinematics.I will discuss the possible origins of this intriguing dichotomy which involves fundamental parameters such as bolometric luminosity, SMBH mass, Eddington ratio

  15. Collapse and Outflow Towards an Integrated Theory of Star Formation

    CERN Document Server

    Pudritz, R E; Ouyed, R

    1997-01-01

    Observational advances over the last decade reveal that star formation is associated with the simultaneous presence of gravitationally collapsing gas, bipolar outflow, and an accretion disk. Two theoretical views of star formation suppose that either stellar mass is determined from the outset by gravitational instability, or by the outflow which sweeps away the collapsing envelope of initially singular density distributions. Neither picture appears to explain all of the facts. This contribution examines some of the key issues facing star formation theory.

  16. C IV emission-line properties and systematic trends in quasar black hole mass estimates

    Science.gov (United States)

    Coatman, Liam; Hewett, Paul C.; Banerji, Manda; Richards, Gordon T.

    2016-09-01

    Black hole masses are crucial to understanding the physics of the connection between quasars and their host galaxies and measuring cosmic black hole-growth. At high redshift, z ≳ 2.1, black hole masses are normally derived using the velocity width of the C IV λ λ1548, 1550 broad emission line, based on the assumption that the observed velocity widths arise from virial-induced motions. In many quasars, the C IV emission line exhibits significant blue asymmetries (`blueshifts') with the line centroid displaced by up to thousands of km s-1 to the blue. These blueshifts almost certainly signal the presence of strong outflows, most likely originating in a disc wind. We have obtained near-infrared spectra, including the Hα λ6565 emission line, for 19 luminous (LBol = 46.5-47.5 erg s-1) Sloan Digital Sky Survey quasars, at redshifts 2 blueshifts present in the population. A strong correlation between C IV velocity width and blueshift is found and, at large blueshifts, >2000 km s-1, the velocity widths appear to be dominated by non-virial motions. Black hole masses, based on the full width at half-maximum of the C IV emission line, can be overestimated by a factor of 5 at large blueshifts. A larger sample of quasar spectra with both C IV and H β, or Hα, emission lines will allow quantitative corrections to C IV-based black hole masses as a function of blueshift to be derived. We find that quasars with large C IV blueshifts possess high Eddington luminosity ratios and that the fraction of high-blueshift quasars in a flux-limited sample is enhanced by a factor of approximately 4 relative to a sample limited by black hole mass.

  17. ANOMALOUSLY STEEP REDDENING LAW IN QUASARS: AN EXCEPTIONAL EXAMPLE OBSERVED IN IRAS 14026+4341

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Peng; Zhou Hongyan; Ji Tuo; Shu Xinwen; Liu Wenjuan; Dong Xiaobo; Wang Huiyuan; Wang Tinggui [Key Laboratory for Research in Galaxies and Cosmology, University of Science and Technology of China, Chinese Academy of Sciences, Hefei, Anhui, 230026 (China); Wang Jianguo [National Astronomical Observatories/Yunnan Observatory, Chinese Academy of Sciences, P.O. Box 110, Kunming, Yunnan 650011 (China); Bai Jinming, E-mail: jpaty@mail.ustc.edu.cn [Polar Research Institute of China, Jinqiao Road 451, Shanghai 200136 (China)

    2013-06-15

    A fraction of the heavily reddened quasars require a reddening curve that is even steeper than that of the Small Magellanic Cloud. In this paper, we thoroughly characterize the anomalously steep reddening law in quasars via an exceptional example observed in IRAS 14026+4341. By comparing the observed spectrum to the quasar composite spectrum, we derive a reddening curve in the rest-frame wavelength range of 1200-10000 A. It has a steep rise at wavelengths shorter than 3000 A, but no significant reddening at longer wavelengths. The absence of dust reddening in the optical continuum is confirmed by the normal broad-line Balmer decrement (the H{alpha}/H{beta} ratio) in IRAS 14026+4341. The anomalous reddening curve can be satisfactorily reproduced with a dust model containing silicate grains in a power-law size distribution, dn(a)/da{proportional_to}a {sup -1.4}, truncated at a maximum size of a{sub max} = 70 nm. The unusual size distribution may be caused by the destruction of large 'stardust' grains by quasar activities or a different dust formation mechanism (i.e., the in situ formation of dust grains in quasar outflows). It is also possible that the analogies of the dust grains observed near the Galactic center are responsible for the steep reddening curve. In addition, we find that IRAS 14026+4341 is a weak emission-line quasar (i.e., PHL 1811 analogies) with heavy dust reddening and blueshifted broad absorption lines.

  18. Astrophysical Jets and Outflows

    CERN Document Server

    De Gouveia dal Pino, E M

    2004-01-01

    Highly collimated supersonic jets and less collimated outflows are observed to emerge from a wide variety of astrophysical objects. They are seen in young stellar objects (YSOs), proto-planetary nebulae, compact objects (like galactic black holes or microquasars, and X-ray binary stars), and in the nuclei of active galaxies (AGNs). Despite their different physical scales (in size, velocity, and amount of energy transported), they have strong morphological similarities. What physics do they share? These systems either hydrodynamic or magnetohydrodynamic (MHD) in nature and are, as such, governed by non-linear equations. While theoretical models helped us to understand the basic physics of these objects, numerical simulations have been allowing us to go beyond the one-dimensional, steady-state approach extracting vital information. In this lecture, the formation, structure, and evolution of the jets are reviewed with the help of observational information, MHD and purely hydrodynamical modeling, and numerical si...

  19. A Quasar-Galaxy Mixing Diagram: Quasar Spectral Energy Distribution Shapes in the Optical to Near-Infrared

    CERN Document Server

    Hao, Heng; Kelly, Brandon C; Civano, Francesca; Bongiorno, Angela; Zamorani, Gianni; Celotti, Annalisa; Ho, Luis C; Merloni, Andrea; Jahnke, Knud; Comastri, Andrea; Trump, Jonathan R; Mainieri, Vincenzo; Salvato, Mara; Brusa, Marcella; Impey, Chris D; Koekemoer, Anton M; Lanzuisi, Giorgio; Vignali, Cristian; Silverman, John D; Urry, C Megan; Schawinski, Kevin

    2012-01-01

    We define the quasar-galaxy mixing diagram by the slopes of the spectral energy distribution (SED) of quasars from $1\\mu m$ to 3000 \\AA\\ and from $1\\mu m$ to 3 $\\mu m$ in the rest frame. The mixing diagram can easily distinguish among quasar-dominated, galaxy-dominated and reddening-dominated SED shapes. By studying the position of the 413 XMM selected Type 1 AGN in the wide-field "Cosmic Evolution Survey" (COSMOS) in the mixing diagram, we find that a combination of the Elvis et al. (1994, hereafter E94) quasar SED with various contributions from galaxy emission and some dust reddening is remarkably effective in describing the SED shape near $1\\mu m$ for large ranges of redshift, luminosity, black hole mass and Eddington ratio of type 1 AGN. In particular, the location in the mixing diagram of the highest luminosity AGN is very close (within 1$\\sigma$) to that expected on the basis of the E94 SED. The mixing diagram can also be used to estimate the host galaxy fraction and reddening in the SED. We also show ...

  20. The SDSS-III BOSS quasar lens survey: discovery of 13 gravitationally lensed quasars

    Science.gov (United States)

    More, Anupreeta; Oguri, Masamune; Kayo, Issha; Zinn, Joel; Strauss, Michael A.; Santiago, Basilio X.; Mosquera, Ana M.; Inada, Naohisa; Kochanek, Christopher S.; Rusu, Cristian E.; Brownstein, Joel R.; da Costa, Luiz N.; Kneib, Jean-Paul; Maia, Marcio A. G.; Quimby, Robert M.; Schneider, Donald P.; Streblyanska, Alina; York, Donald G.

    2016-02-01

    We report the discovery of 13 confirmed two-image quasar lenses from a systematic search for gravitationally lensed quasars in the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS). We adopted a methodology similar to that used in the SDSS Quasar Lens Search (SQLS). In addition to the confirmed lenses, we report 11 quasar pairs with small angular separations ( ≲ 2 arcsec) confirmed from our spectroscopy, which are either projected pairs, physical binaries, or possibly quasar lens systems whose lens galaxies have not yet been detected. The newly discovered quasar lens system, SDSS J1452+4224 at zs ≈ 4.8 is one of the highest redshift multiply imaged quasars found to date. Furthermore, we have over 50 good lens candidates yet to be followed up. Owing to the heterogeneous selection of BOSS quasars, the lens sample presented here does not have a well-defined selection function.

  1. The SDSS-III BOSS quasar lens survey: discovery of thirteen gravitationally lensed quasars

    CERN Document Server

    More, Anupreeta; Kayo, Issha; Zinn, Joel; Strauss, Michael A; Santiago, Basilio X; Mosquera, Ana M; Inada, Naohisa; Kochanek, Christopher S; Rusu, Cristian E; Brownstein, Joel R; da Costa, Luiz N; Kneib, Jean-Paul; Maia, Marcio A G; Quimby, Robert M; Schneider, Donald P; Streblyanska, Alina; York, Donald G

    2015-01-01

    We report the discovery of 13 confirmed two-image quasar lenses from a systematic search for gravitationally lensed quasars in the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS). We adopted a methodology similar to that used in the SDSS Quasar Lens Search (SQLS). In addition to the confirmed lenses, we report 11 quasar pairs with small angular separations ($\\lesssim$2") confirmed from our spectroscopy, which are either projected pairs, physical binaries, or possibly quasar lens systems whose lens galaxies have not yet been detected. The newly discovered quasar lens system, SDSS J1452+4224 at zs$\\approx$4.8 is one of the highest redshift multiply imaged quasars found to date. Furthermore, we have over 50 good lens candidates yet to be followed up. Owing to the heterogeneous selection of BOSS quasars, the lens sample presented here does not have a well-defined selection function.

  2. Quasar structure from microlensing in gravitationally lensed quasars

    Science.gov (United States)

    Morgan, Christopher Warren

    2008-02-01

    I analyze microlensing in gravitationally lensed quasars to yield measurements of the structure of their continuum emission regions. I first describe our lensed quasar monitoring program and RETROCAM, the auxiliary port camera I built for the 2.4m Hiltner telescope to monitor lensed quasars. I describe the application of our Monte Carlo microlensing analysis technique to SDSS 0924+0219, a system with a highly anomalous optical flux ratio. For an inclination angle i, I find an optical scale radius log[( r s /cm)[Special characters omitted.] ] = [Special characters omitted.] . I extrapolate the best-fitting light curves into the future to find a roughly 45% probability that the anomalous image (D) will brighten by at least an order of magnitude during the next decade. I expand our method to make simultaneous estimates of the time delays and structure of HE1104-1805 and QJ0158-4325, two doubly-imaged quasars with microlensing and intrinsic variability on comparable time scales. For HE1104- 1805 I find a time delay of D t AB = t A - t B = [Special characters omitted.] days and estimate a scale radius of log[( r s /cm)[Special characters omitted.] ] = [Special characters omitted.] at 0.2mm in the rest frame. I am unable to measure a time delay for QJ0158-4325, but the scale radius is log[( r s /cm) [Special characters omitted.] ] = 14.9 ±1 0.3 at 0.3mm in the rest frame. I then apply our Monte Carlo microlensing analysis technique to the optical light curves of 11 lensed quasar systems to show that quasar accretion disk sizes at 2500Å are related to black hole mass ( M BH ) by log( R 2500 /cm) = (15.7 ± 0.16) + (0.64± 0.18) log( M BH /10 9 [Special characters omitted.] ). This scaling is consistent with the expectation from thin disk theory (R 0( [Special characters omitted.] ), but it implies that black holes radiate with relatively low efficiency, log(e) = -1.54 ± 0.36 + log( L/L E ) where e=3D L / ( M c 2 ). These sizes are also larger, by a factor of ~ 3, than

  3. Spectroscopic Identification of Type 2 Quasars at Z < 1 in SDSS-III/BOSS

    CERN Document Server

    Yuan, Sihan; Zakamska, Nadia L

    2016-01-01

    The physics and demographics of type 2 quasars remain poorly understood, and new samples of such objects selected in a variety of ways can give insight into their physical properties, evolution, and relationship to their host galaxies. We present a sample of 2758 type 2 quasars at z $\\leq$ 1 from the SDSS-III/BOSS spectroscopic database, selected on the basis of their emission-line properties. We probe the luminous end of the population by requiring the rest-frame equivalent width of [OIII] to be > 100 {\\AA}. We distinguish our objects from star-forming galaxies and type 1 quasars using line widths, standard emission line ratio diagnostic diagrams at z 0.52. The majority of our objects have [OIII] luminosities in the range 10^8.5-10^10 L$_{\\odot}$ and redshifts between 0.4 and 0.65. Our sample includes over 400 type 2 quasars with incorrectly measured redshifts in the BOSS database; such objects often show kinematic substructure or outflows in the [OIII] line. The majority of the sample has counterparts in t...

  4. The Origins of a Rich Absorption Line Complex in a Quasar at Redshift 3.45

    CERN Document Server

    Simon, Leah E

    2010-01-01

    We discuss the nature and origin of a rich complex of narrow absorption lines in the quasar J102325.31+514251.0 at redshift 3.447. We measure nine C IV(\\lambda1548,1551) absorption line systems with velocities from -1400 to -6200 km/s, and full widths at half minimum ranging from 16 to 350 km/s. We also detect other absorption lines in these systems, including H I, C III, N V, O VI, and Si IV. Lower ionisation lines are not present, indicating a generally high degree of ionisation in all nine systems. The total hydrogen column densities range from = 1-8 Z_{sun}. The lowest velocity system, which has an ambiguous location, also has the lowest metallicity, Z <= 0.3 Z_{sun}, and might form in a non-outflow environment farther from the quasar. Overall, however, this complex of narrow absorption lines can be identified with a highly structured, multi-component ou tflow from the quasar. The high metallicities are similar to those derived for other quasars at similar redshifts and luminosities, and are consistent...

  5. MEAN SPECTRAL ENERGY DISTRIBUTIONS AND BOLOMETRIC CORRECTIONS FOR LUMINOUS QUASARS

    Energy Technology Data Exchange (ETDEWEB)

    Krawczyk, Coleman M.; Richards, Gordon T.; Mehta, Sajjan S.; Vogeley, Michael S. [Department of Physics, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104 (United States); Gallagher, S. C. [Department of Physics and Astronomy, The University of Western Ontario, London, ON N6A 3K7 (Canada); Leighly, Karen M. [Homer L. Dodge Department of Physics and Astronomy, The University of Oklahoma, 440 W. Brooks Street, Norman, OK 73019 (United States); Ross, Nicholas P. [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Schneider, Donald P. [Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States)

    2013-05-01

    We explore the mid-infrared (mid-IR) through ultraviolet (UV) spectral energy distributions (SEDs) of 119,652 luminous broad-lined quasars with 0.064 < z < 5.46 using mid-IR data from Spitzer and WISE, near-infrared data from the Two Micron All Sky Survey and UKIDSS, optical data from the Sloan Digital Sky Survey, and UV data from the Galaxy Evolution Explorer. The mean SED requires a bolometric correction (relative to 2500 A) of BC{sub 2500A} =2.75 {+-} 0.40 using the integrated light from 1 {mu}m-2 keV, and we further explore the range of bolometric corrections exhibited by individual objects. In addition, we investigate the dependence of the mean SED on various parameters, particularly the UV luminosity for quasars with 0.5 {approx}< z {approx}< 3 and the properties of the UV emission lines for quasars with z {approx}> 1.6; the latter is a possible indicator of the strength of the accretion disk wind, which is expected to be SED-dependent. Luminosity-dependent mean SEDs show that, relative to the high-luminosity SED, low-luminosity SEDs exhibit a harder (bluer) far-UV spectral slope ({alpha}{sub UV}), a redder optical continuum, and less hot dust. Mean SEDs constructed instead as a function of UV emission line properties reveal changes that are consistent with known Principal Component Analysis trends. A potentially important contribution to the bolometric correction is the unseen extreme UV (EUV) continuum. Our work suggests that lower-luminosity quasars and/or quasars with disk-dominated broad emission lines may require an extra continuum component in the EUV that is not present (or much weaker) in high-luminosity quasars with strong accretion disk winds. As such, we consider four possible models and explore the resulting bolometric corrections. Understanding these various SED-dependent effects will be important for accurate determination of quasar accretion rates.

  6. The JCMT Gould Belt Survey: Understanding the influence of molecular outflows on Gould Belt clouds

    CERN Document Server

    Drabek-Maunder, E; Buckle, J V; Di Francesco, J; Richer, J

    2015-01-01

    Using JCMT Gould Belt Survey data from CO J=3-2 isotopologues, we present a meta-analysis of the outflows and energetics of star-forming regions in several Gould Belt clouds. The majority of the regions are strongly gravitationally bound. There is evidence that molecular outflows transport large quantities of momentum and energy. Outflow energies are at least 20 per cent of the total turbulent kinetic energies in all of the regions studied and greater than the turbulent energy in half of the regions. However, we find no evidence that outflows increase levels of turbulence, and there is no correlation between the outflow and turbulent energies. Even though outflows in some regions contribute significantly to maintaining turbulence levels against dissipation, this relies on outflows efficiently coupling to bulk motions. Other mechanisms (e.g. supernovae) must be the main drivers of turbulence in most if not all of these regions.

  7. Systematic effects in large-scale angular power spectra of photometric quasars and implications for constraining primordial nongaussianity

    CERN Document Server

    Pullen, Anthony R

    2013-01-01

    Primordial non-Gaussianity of local type is predicted to lead to enhanced halo clustering on very large scales. Photometric quasars, which can be seen from cosmological redshifts z>2 even in wide-shallow optical surveys, are promising tracers for constraining non-Gaussianity using this effect. However, large-scale systematics can also mimic this signature of non-Gaussianity. In order to assess the contribution of systematic effects, we cross-correlate overdensity maps of photometric quasars from the Sloan Digital Sky Survey (SDSS) Data Release 6 (DR6) in different redshift ranges. We find that the maps are significantly correlated on large scales, even though we expect the angular distributions of quasars at different redshifts to be uncorrelated. This implies that the quasar maps are contaminated with systematic errors. We investigate the use of external templates that provide information on the spatial dependence of potential systematic errors to reduce the level of spurious clustering in the quasar data. W...

  8. High Redshift Quasars and Star Formation History

    CERN Document Server

    Dietrich, M; Dietrich, Matthias; Hamann, Fred

    2001-01-01

    Quasars are among the most luminous objects in the universe, and they can be studied in detail up to the highest known redshift. Assuming that the gas associated with quasars is closely related to the interstellar medium of the host galaxy, quasars can be used as tracer of the star formation history in the early universe. We have observed a small sample of quasars at redshifts 3= 10, corresponding to an age of the universe of less than 5*10^8 yrs (H_o = 65 km/s/Mpc, Omega_M = 0.3, Omega_Lambda = 0.7).

  9. Galaxy evolution. Black hole feedback in the luminous quasar PDS 456.

    Science.gov (United States)

    Nardini, E; Reeves, J N; Gofford, J; Harrison, F A; Risaliti, G; Braito, V; Costa, M T; Matzeu, G A; Walton, D J; Behar, E; Boggs, S E; Christensen, F E; Craig, W W; Hailey, C J; Matt, G; Miller, J M; O'Brien, P T; Stern, D; Turner, T J; Ward, M J

    2015-02-20

    The evolution of galaxies is connected to the growth of supermassive black holes in their centers. During the quasar phase, a huge luminosity is released as matter falls onto the black hole, and radiation-driven winds can transfer most of this energy back to the host galaxy. Over five different epochs, we detected the signatures of a nearly spherical stream of highly ionized gas in the broadband x-ray spectra of the luminous quasar PDS 456. This persistent wind is expelled at relativistic speeds from the inner accretion disk, and its wide aperture suggests an effective coupling with the ambient gas. The outflow's kinetic power larger than 10(46) ergs per second is enough to provide the feedback required by models of black hole and host galaxy coevolution.

  10. Intranight optical variability of radio-loud broad absorption line quasars

    CERN Document Server

    Joshi, Ravi

    2012-01-01

    We present the results of an optical photometric monitoring program of 10 extremely radio loud broad absorption line quasars (RL-BALQSOs) with radio-loudness parameter, R, greater than 100 and magnitude g_i < 19. Over an observing run of about 3.5-6.5 hour we found a clear detection of variability for one of our 10 radio-loud BALQSOs with the INOV duty cycle of 5.1 per cent, while on including the probable variable cases, a higher duty cycle of 35.1 per cent is found; which are very similar to the duty cycle of radio quiet broad absorption line quasars (RQ-BALQSOs). This low duty cycle of clear variability per cent in radio-loud sub-class of BALQSOs can be understood under the premise where BALs outflow may arise from large variety of viewing angles from the jet axis or perhaps being closer to the disc plane.

  11. Astrophysical jets and outflows

    Science.gov (United States)

    de Gouveia Dal Pino, Elisabete M.

    Highly collimated supersonic jets and less collimated outflows are observed to emerge from a wide variety of astrophysical objects. They are seen in young stellar objects (YSOs), proto-planetary nebulae, compact objects (like galactic black holes or microquasars, and X-ray binary stars), and in the nuclei of active galaxies (AGNs). Despite their different physical scales (in size, velocity, and amount of energy transported), they have strong morphological similarities. What physics do they share? These systems are either hydrodynamic or magnetohydrodynamic (MHD) in nature and are, as such, governed by non-linear equations. While theoretical models helped us to understand the basic physics of these objects, numerical simulations have been allowing us to go beyond the one-dimensional, steady-state approach extracting vital information. In this lecture, the formation, structure, and evolution of the jets are reviewed with the help of observational information, MHD and purely hydrodynamical modeling, and numerical simulations. Possible applications of the models particularly to YSOs and AGN jets are addressed.

  12. The rotating wind of the quasar PG 1700+518.

    Science.gov (United States)

    Young, S; Axon, D J; Robinson, A; Hough, J H; Smith, J E

    2007-11-01

    It is now widely accepted that most galaxies undergo an active phase, during which a central super-massive black hole generates vast radiant luminosities through the gravitational accretion of gas. Winds launched from a rotating accretion disk surrounding the black hole are thought to play a critical role, allowing the disk to shed angular momentum that would otherwise inhibit accretion. Such winds are capable of depositing large amounts of mechanical energy in the host galaxy and its environs, profoundly affecting its formation and evolution, and perhaps regulating the formation of large-scale cosmological structures in the early Universe. Although there are good theoretical grounds for believing that outflows from active galactic nuclei originate as disk winds, observational verification has proven elusive. Here we show that structures observed in polarized light across the broad Halpha emission line in the quasar PG 1700+518 originate close to the accretion disk in an electron scattering wind. The wind has large rotational motions (approximately 4,000 km s(-1)), providing direct observational evidence that outflows from active galactic nuclei are launched from the disks. Moreover, the wind rises nearly vertically from the disk, favouring launch mechanisms that impart an initial acceleration perpendicular to the disk plane.

  13. Investigating the radio-loud phase of BAL quasars

    CERN Document Server

    Bruni, G; Pedani, M; Benn, C R; Mack, K -H; Holt, J; Montenegro-Montes, F M; Jiménez-Luján, F

    2014-01-01

    Broad Absorption Lines (BALs) are present in the spectra of ~20% of quasars (QSOs), indicating the presence of fast outflows (up to 0.2c) intercepting the observer's line of sight. Radio-Loud (RL) BAL QSOs are even more rare, being four times less common than Radio-Quiet (RQ) BAL QSOs. The reason for that is still not clear, leaving open questions about the nature of the BAL-producing outflows and their connection with the radio jet. We explored the spectroscopic characteristics of RL and RQ BAL QSOs, aiming at finding a possible explanation for the rarity of the former. We identified two samples of genuine BAL QSOs from SDSS optical spectra, one RL and one RQ, in a suitable redshift interval (2.5< z <3.5) that allowed us to observe the Mg II and H$\\beta$ emission lines in the adjacent Near-Infrared (NIR) band. We collected NIR spectra of the two samples using the Telescopio Nazionale Galileo (TNG, Canary Islands). Using relations known in the literature, we could estimate black hole mass, broad line re...

  14. Sensitive radio survey of obscured quasar candidates

    Science.gov (United States)

    Alexandroff, Rachael M.; Zakamska, Nadia L.; van Velzen, Sjoert; Greene, Jenny E.; Strauss, Michael A.

    2016-12-01

    We study the radio properties of moderately obscured quasars in samples at both low (z ˜ 0.5) and high (z ˜ 2.5) redshift to understand the role of radio activity in accretion, using the Karl G. Jansky Very Large Array (VLA) at 6.0 GHz and 1.4 GHz. Our z ˜ 2.5 sample consists of optically selected obscured quasar candidates, all of which are radio-quiet, with typical radio luminosities of νLν[1.4 GHz] ≲ 1040 erg s-1. Only a single source is individually detected in our deep (rms˜10 μJy) exposures. This population would not be identified by radio-based selection methods used for distinguishing dusty star-forming galaxies and obscured active nuclei. In our pilot A-array study of z ˜ 0.5 radio-quiet quasars, we spatially resolve four of five objects on scales ˜5 kpc and find they have steep spectral indices with an average value of α = -0.75. Therefore, radio emission in these sources could be due to jet-driven or radiatively driven bubbles interacting with interstellar material on the scale of the host galaxy. Finally, we also study the additional population of ˜200 faint ( ˜ 40 μJy-40 mJy) field radio sources observed over ˜120 arcmin2 of our data. 60 per cent of these detections (excluding our original targets) are matched in the Sloan Digital Sky Survey (SDSS) and/or Wide-Field Infrared Survey Explorer (WISE) and are, in roughly equal shares, active galactic nuclei (AGN) at a broad range of redshifts, passive galaxies with no other signs of nuclear activity and infrared-bright but optically faint sources. Spectroscopically or photometrically confirmed star-forming galaxies constitute only a small minority of the matches. Such sensitive radio surveys allow us to address important questions of AGN evolution and evaluate the AGN contribution to the radio-quiet sky.

  15. Energy exchanges in reconnection outflows

    Science.gov (United States)

    Lapenta, Giovanni; Goldman, Martin V.; Newman, David L.; Markidis, Stefano

    2017-01-01

    Reconnection outflows are highly energetic directed flows that interact with the ambient plasma or with flows from other reconnection regions. Under these conditions the flow becomes highly unstable and chaotic, as any flow jets interacting with a medium. We report here massively parallel simulations of the two cases of interaction between outflow jets and between a single outflow with an ambient plasma. We find in both case the development of a chaotic magnetic field, subject to secondary reconnection events that further complicate the topology of the field lines. The focus of the present analysis is on the energy balance. We compute each energy channel (electromagnetic, bulk, thermal, for each species) and find where the most energy is exchanged and in what form. The main finding is that the largest energy exchange is not at the reconnection site proper but in the regions where the outflowing jets are destabilized.

  16. Four quasars above redshift 6 discovered by the Canada-France High-z Quasar Survey

    CERN Document Server

    Willott, Chris J; Omont, Alain; Bergeron, Jacqueline; Delfosse, Xavier; Forveille, Thierry; Albert, Loic; Reyle, Celine; Hill, Gary J; Gully-Santiago, Michael; Vinten, Phillip; Crampton, David; Hutchings, John B; Schade, David; Simard, Luc; Sawicki, Marcin; Beelen, Alexandre; Cox, Pierre

    2007-01-01

    The Canada-France High-z Quasar Survey (CFHQS) is an optical survey designed to locate quasars during the epoch of reionization. In this paper we present the discovery of the first four CFHQS quasars at redshift greater than 6, including the most distant known quasar, CFHQS J2329-0301 at z=6.43. We describe the observational method used to identify the quasars and present optical, infrared, and millimeter photometry and optical and near-infrared spectroscopy. We investigate the dust properties of these quasars finding an unusual dust extinction curve for one quasar and a high far-infrared luminosity due to dust emission for another. The mean millimeter continuum flux for CFHQS quasars is substantially lower than that for SDSS quasars at the same redshift, likely due to a correlation with quasar UV luminosity. For two quasars with sufficiently high signal-to-noise optical spectra, we use the spectra to investigate the ionization state of hydrogen at z>5. For CFHQS J1509-1749 at z=6.12, we find significant evol...

  17. Evidence for Quasar Activity Triggered by Galaxy Mergers in HST Observations of Dust-reddened Quasars

    Science.gov (United States)

    Urrutia, Tanya; Lacy, Mark; Becker, Robert H.

    2008-02-01

    We present Hubble Space Telescope ACS images of 13 dust-reddened type 1 quasars selected from the FIRST/2MASS Red Quasar Survey. These quasars have high intrinsic luminosities after correction for dust obscuration (-23.5 >= MB >= - 26.2 from K-magnitude). The images show strong evidence of recent or ongoing interaction in 11 of the 13 cases, even before the quasar nucleus is subtracted. None of the host galaxies are well fit by a simple elliptical profile. The fraction of quasars showing interaction is significantly higher than the 30% seen in samples of host galaxies of normal, unobscured quasars. There is a weak correlation between the amount of dust reddening and the magnitude of interaction in the host galaxy, measured using the Gini coefficient and the concentration index. Although few host galaxy studies of normal quasars are matched to ours in intrinsic quasar luminosity, no evidence has been found for a strong dependence of merger activity on host luminosity in samples of the host galaxies of normal quasars. We thus believe that the high merger fraction in our sample is related to their obscured nature, with a significant amount of reddening occurring in the host galaxy. The red quasar phenomenon seems to have an evolutionary explanation, with the young quasar spending the early part of its lifetime enshrouded in an interacting galaxy. This might be further indication of a link between AGNs and starburst galaxies.

  18. The Nature of Partial Covering in Broad Absorption Line Quasars

    Science.gov (United States)

    Leighly, Karen

    2012-10-01

    Ejected gas is seen as broad absorption lines in 20% of quasars. It has been known for 15 years that prominent lines such as CIV are usually saturated but not black because the absorbing gas only partially covers the continuum emission region. Therefore, column densities estimated from these lines are only lower limits. Accurate column densities can be obtained from rare ions that have two or more transitions from the same lower level, so that the optical depth and covering fraction can be solved for simultanously. Suitable lines are hard to find, so such measurements are rare. We have found that metastable helium is particularly useful for these measurements. Yet despite these advances, partial covering remains a just a parameter and its physical nature is not understood.We propose a unique experiment to constrain the physical nature of partial covering. We will compare the covering fraction measured from PV {a doublet in the far UV} with that measured from metastable HeI {optical and IR}. The ions creating these lines are relatively rare, and they present similar opacity over a wide range of gas parameters. But due to their wide wavelength separation, these lines probe dramatically different regions of the continuum source, the temperature-dependent accretion disk. So we expect different covering fraction behavior for different partial covering scenarios. This experiment is relevant for understanding the geometry and clumpiness of the outflow, and the results may impact our understanding of the global covering fraction, a parameter critical for determining the outflow kinetic luminosity, and thereby estimating feedback efficiency for broad absorption line outflows.

  19. Metal enrichment by radiation pressure in active galactic nucleus outflows -- theory and observations

    CERN Document Server

    Baskin, Alexei

    2012-01-01

    Outflows from active galactic nuclei may be produced by absorption of continuum radiation by UV resonance lines of abundant metal ions, as observed in broad absorption line quasars (BALQs). The radiation pressure exerted on the metal ions is coupled to the rest of the gas through Coulomb collisions of the metal ions. We calculate the photon density and gas density which allow decoupling of the metal ions from the rest of the gas. These conditions may lead to an outflow composed mostly of the metal ions. We derive a method to constrain the metals/H ratio of observed UV outflows, based on the Ly {\\alpha} and Si iv {\\lambda}{\\lambda}1394, 1403 absorption profiles. We apply this method to an SDSS sample of BALQs to derive a handful of candidate outflows with a higher than solar metal/H ratio. This mechanism can produce ultra fast UV outflows, if a shield of the continuum source with a strong absorption edge is present.

  20. The Neutrino Ball Model of a Quasar

    CERN Document Server

    Manka, R; Karczewska, D

    1993-01-01

    It is suggested that the nonorthodox model of a quasar as a neutrino ball described in terms of the standard model extended by adding right-handed neutrinos and the Majorana scalar field can be presented in order to explain a quasar as a body of weak interacting neutrinos. Neutrino interaction with the scalar Majorana field violates the lepton number and produces the mass splitting of the neutrino due to the sea-saw mechanism. In this model a quasar is an object which appears in the result of the first order cosmological phase transition. In this interpretation a quasar may be regarded as a ball filled with Dirac neutrinos and can be treated as a remnant of phase transition with unbroken global lepton symmetry. In this paper we study the macroscopic parameters of such a configuration. In the result the mass-radius curve M(R) for the quasar is obtained.

  1. Ionized Absorbers in Active Galactic Nuclei and Very Steap Soft X-Ray Quasars

    Science.gov (United States)

    Fiore, Fabrizio; White, Nicholas (Technical Monitor)

    2000-01-01

    Steep soft X-ray (0.1-2 keV) quasars share several unusual properties: narrow Balmer lines, strong Fe II emission, large and fast X-ray variability, and a rather steep 2-10 keV spectrum. These intriguing objects have been suggested to be the analogues of Galactic black hole candidates in the high, soft state. We present here results from ASCA observations for two of these quasars: NAB 0205 + 024 and PG 1244 + 026. Both objects show similar variations (factor of approximately 2 in 10 ks), despite a factor of approximately 10 difference in the 0.5-10 keV luminosity (7.3 x 10(exp 43) erg/s for PG 1244 + 026 and 6.4 x 10(exp 44) erg/s for NAB 0205 + 024, assuming isotropic emission, H(sub 0) = 50.0 and q(sub 0) = 0.0). The X-ray continuum of the two quasars flattens by 0.5-1 going from the 0.1-2 keV band towards higher energies, strengthening recent results on another half-dozen steep soft X-ray active galactic nuclei. PG 1244 + 026 shows a significant feature in the '1-keV' region, which can be described either as a broad emission line centered at 0.95 keV (quasar frame) or as edge or line absorption at 1.17 (1.22) keV. The line emission could be a result of reflection from a highly ionized accretion disc, in line with the view that steep soft X-ray quasars are emitting close to the Eddington luminosity. Photoelectric edge absorption or resonant line absorption could be produced by gas outflowing at a large velocity (0.3-0.6 c).

  2. Evidence for the alignment of quasar radio polarizations with large quasar group axes

    Science.gov (United States)

    Pelgrims, V.; Hutsemékers, D.

    2016-05-01

    Recently, evidence has been presented for the polarization vectors from quasars to preferentially align with the axes of the large quasar groups (LQG) to which they belong. This report was based on observations made at optical wavelengths for two LQGs at redshift ~1.3. The correlation suggests that the spin axes of quasars preferentially align with their surrounding large-scale structure that is assumed to be traced by the LQGs. Here, we consider a large sample of LQGs built from the Sloan Digital Sky Survey DR7 quasar catalogue in the redshift range 1.0-1.8. For quasars embedded in this sample, we collected radio polarization measurements with the goal to study possible correlations between quasar polarization vectors and the major axis of their host LQGs. Assuming the radio polarization vector is perpendicular to the quasar spin axis, we found that the quasar spin axis is preferentially parallel to the LQG major axis inside LQGs that have at least 20 members. This result independently supports the observations at optical wavelengths. We additionally found that when the richness of an LQG decreases, the quasar spin axis becomes preferentially perpendicular to the LQG major axis and that no correlation is detected for quasar groups with fewer than 10 members.

  3. Tracing dark energy with quasars

    CERN Document Server

    Średzińska, J; Bilicki, M; Hryniewicz, K; Krupa, M; Kurcz, A; Marziani, P; Pollo, A; Pych, W; Udalski, A

    2016-01-01

    The nature of dark energy, driving the accelerated expansion of the Universe, is one of the most important issues in modern astrophysics. In order to understand this phenomenon, we need precise astrophysical probes of the universal expansion spanning wide redshift ranges. Quasars have recently emerged as such a probe, thanks to their high intrinsic luminosities and, most importantly, our ability to measure their luminosity distances independently of redshifts. Here we report our ongoing work on observational reverberation mapping using the time delay of the Mg II line, performed with the South African Large Telescope (SALT).

  4. Keck/ESI Long-slit Spectroscopy of SBS 1421+511: A Recoiling Quasar Nucleus in An Active Galaxy Pair?

    CERN Document Server

    Sun, Luming; Hao, Lei; Jiang, Peng; Ge, Jian; Ji, Tuo; Ma, Jingzhe; Zhang, Shaohua; Shu, Xinwen

    2015-01-01

    We present Keck/ESI long-slit spectroscopy of SBS 1421+511, a system consisting of a quasar at z = 0.276 and an extended source 3" northern to the quasar. The quasar shows a blue-skewed profile of Balmer broad emission lines, which can be well modeled as emissions from a circular disk with a blueshift velocity of ~1400 km/s. The blueshift is better interpreted as resulting from a recoiling active black hole than from a super-massive black hole binary, since the line profile almost kept steady over one decade in the quasar rest-frame. Alternative interpretations are possible as well, such as emissions from a bipolar outflow or a circular disk with spiral emissivity perturbations. The extended source shows Seyfert-like narrow line ratios and a [OIII] luminosity of >1.4\\times10^8L_\\odot, with almost the same redshift as the quasar and a projected distance of 12.5 kpc at the redshift. SBS 1421+511 is thus likely to be an interacting galaxy pair with dual AGN. Alternatively, the quasar companion only appears to be...

  5. Outflow from Hot Accretion Flows

    CERN Document Server

    Yuan, Feng; Wu, Maochun

    2012-01-01

    Numerical simulations of hot accretion flows have shown that the mass accretion rate decreases with decreasing radius. Two models have been proposed to explain this result. In the adiabatic inflow-outflow solution (ADIOS), it is thought to be due to the loss of gas in outflows. In the convection-dominated accretion flow (CDAF) model, it is explained as because that the gas is locked in convective eddies. In this paper we use hydrodynamical (HD) and magnetohydrodynamical (MHD) simulations to investigate which one is physical. We calculate and compare various properties of inflow (gas with an inward velocity) and outflow (gas with an outward velocity). Systematic and significant differences are found. For example, for HD flows, the temperature of outflow is higher than inflow; while for MHD flows, the specific angular momentum of outflow is much higher than inflow. We have also analyzed the convective stability of MHD accretion flow and found that they are stable. These results suggest that systematic inward an...

  6. A Compton-thick Wind in the High Luminosity Quasar, PDS 456

    Science.gov (United States)

    Reeves, J. N.; O'Brien, P. T.; Behar, E.; Miller, L.; Turner, T. J.; Braito, V.; Fabian, A. C.; Kaspi, S.; Mushotzky, R.; Ward, M.

    2009-01-01

    PDS 456 is a nearby (z=0.184), luminous (L(sub bol) approximately equal to 10(exp 47) ergs(exp -1) type I quasar. A deep 190 ks Suzaku observation in February 2007 revealed the complex, broad band X-ray spectrum of PDS 456. The Suzaku spectrum exhibits highly statistically significant absorption features near 9 keV in the quasar rest-frame. We show that the most plausible origin of the absorption is from blue-shifted resonance (1s-2p) transitions of hydrogen-like iron (at 6.97 keV in the rest frame). This indicates that a highly ionized outflow may be present moving at near relativistic velocities (0.26-0.31c). A possible hard X-ray excess is detected above 15 keV with HXD (at 99.8% confidence), which may arise from high column density gas (N(sub H) greater than 10(exp 24)cm(exp -2) partially covering the X-ray emission, or through strong Compton reflection. Here we propose that the iron K-shell absorption in PDS 456 is associated with a thick, possibly clumpy outflow, covering about 20% of 4(pi) steradian solid angle. The outflow is likely launched from the inner accretion disk, within 15-100 gravitational radii of the black hole. The kinetic power of the outflow may be similar to the bolometric luminosity of PDS 456. Such a powerful wind could have a significant effect on the co-evolution of the host galaxy and its supermassive black hole, through feedback.

  7. The warm absorber in the radio-loud quasar 4C +74.26

    Science.gov (United States)

    Di Gesu, L.; Costantini, E.

    2016-10-01

    Outflows of photoionized gas are commonly detected in the X-ray spectra of Seyfert 1 galaxies. However, the evidence for this phenomenon in broad line radio galaxies, which are analogous to Seyfert 1 galaxies in the radio-loud regime, has so far been scarce. Here, we present the analysis of the X-ray absorption in the radio-loud quasar 4C +74.26. With the aim of characterizing the kinetic and the ionization conditions of the absorbing material, we fitted jointly the XMM-Newton Reflection Grating Spectrometer (RGS) and the Chandra High Energy Transmission Grating Spectrometer (HETGS) spectra, which were taken 4 months apart. The intrinsic continuum flux did not vary significantly during this time lapse. The spectrum shows the absorption signatures (e.g., Fe-UTA, O vii, and Ne vii-Ne x) of a photoionized gas outflow (NH ~ 3.5 × 1021 cm-2, log ξ ~ 2.6, vout ~ 3600 km s-1) located at the redshift of source. We estimate that the gas is located outside the broad line region but within the boundaries of the putative torus. This ionized absorber is consistent with the X-ray counterpart of a polar scattering outflow reported in the optical band for this source. The kinetic luminosity carried by the outflow is insufficient to produce a significant feedback is this quasar. Finally, we show that the heavy soft X-ray absorption that was noticed in the past for this source arises mostly in the Galactic interstellar medium.

  8. New Perspective on Galaxy Outflows From the First Detection of Both Intrinsic and Traverse Metal-Line Absorption

    CERN Document Server

    Kacprzak, Glenn G; Bouché, Nicolas; Churchill, Christopher W; Cooke, Jeff; LeReun, Audrey; Schroetter, Ilane; Ho, Stephanie H; Klimek, Elizabeth

    2014-01-01

    We present the first observation of a galaxy (z=0.2) that exhibits metal-line absorption back-illuminated by the galaxy ("down-the-barrel") and transversely by a background quasar at a projected distance of 58 kpc. Both absorption systems, traced by MgII, are blueshifted relative to the galaxy systemic velocity. The quasar sight-line, which resides almost directly along the projected minor axis of the galaxy, probes MgI and MgII absorption obtained from Keck/LRIS and Lya, SiII and SiIII absorption obtained from HST/COS. For the first time, we combine two independent models used to quantify the outflow properties for down-the-barrel and transverse absorption. We find that the modeled down-the-barrel deprojected outflow velocities range between $V_{dtb}=45-255$ km/s. The transverse bi-conical outflow model, assuming constant-velocity flows perpendicular to the disk, requires wind velocities $V_{outflow}=40-80$ km/s to reproduce the transverse MgII absorption kinematics, which is consistent with the range of $V_...

  9. Updating quasar bolometric luminosity corrections - III. [O iii] bolometric corrections

    Science.gov (United States)

    Pennell, Alison; Runnoe, Jessie C.; Brotherton, M. S.

    2017-06-01

    We present quasar bolometric corrections using the [O III] λ 5007 narrow emission line luminosity based on the detailed spectral energy distributions of 53 bright quasars at low to moderate redshift (0.0345 diversity, introduces scatter into the L_{[O III]}-Liso relationship. We found that the {[O III]} bolometric correction can be significantly improved by adding a term including the equivalent width ratio R_{Fe II} ≡ EW_{{Fe II}}/EW_{Hβ }, which is an EV1 indicator. Inclusion of R_{Fe II} in predicting Liso is significant at nearly the 3σ level and reduces the scatter and systematic offset of the luminosity residuals. Typically, {[O III]} bolometric corrections are adopted for Type 2 sources where the quasar continuum is not observed and in these cases, R_{Fe II} cannot be measured. We searched for an alternative measure of EV1 that could be measured in the optical spectra of Type 2 sources but were unable to identify one. Thus, the main contribution of this work is to present an improved {[O III]} bolometric correction based on measured bolometric luminosities and highlight the EV1 dependence of the correction in Type 1 sources.

  10. Knowledge Outflows from Foreign Subsidiaries

    DEFF Research Database (Denmark)

    Perri, Alessandra; Andersson, Ulf

    This paper analyzes the MNC subsidiaries’ trade-off between the need for knowledge creation and the need for knowledge protection, and relates it to the extent of knowledge outflows generated within the host location. Combining research in International Business with Social Theory, we find......-mediated local knowledge outflows, as well as to the broad IB literature on the relationship between subsidiaries and their host regions. The implications for managers and policy-makers are also discussed....... that subsidiaries that extensively draw on external knowledge sources are also more likely to generate knowledge outflows to local firms. We argue that this may be explained by the subsidiaries’ willingness to build the trust that facilitates the establishment of reciprocal knowledge linkages. However, when...

  11. NEW PERSPECTIVE ON GALAXY OUTFLOWS FROM THE FIRST DETECTION OF BOTH INTRINSIC AND TRAVERSE METAL-LINE ABSORPTION

    Energy Technology Data Exchange (ETDEWEB)

    Kacprzak, Glenn G.; Cooke, Jeff [Swinburne University of Technology, Victoria 3122 (Australia); Martin, Crystal L.; Ho, Stephanie H. [Physics Department, University of California, Santa Barbara, CA 93106 (United States); Bouché, Nicolas; LeReun, Audrey; Schroetter, Ilane [CNRS, Institut de Recherche en Astrophysique et Planétologie (IRAP) de Toulouse, 14 Avenue E. Belin, F-31400 Toulouse (France); Churchill, Christopher W.; Klimek, Elizabeth, E-mail: gkacprzak@astro.swin.edu.au [New Mexico State University, Las Cruces, NM 88003 (United States)

    2014-09-01

    We present the first observation of a galaxy (z = 0.2) that exhibits metal-line absorption back-illuminated by the galaxy (down-the-barrel) and transversely by a background quasar at a projected distance of 58 kpc. Both absorption systems, traced by Mg II, are blueshifted relative to the galaxy systemic velocity. The quasar sight line, which resides almost directly along the projected minor axis of the galaxy, probes Mg I and Mg II absorption obtained from the Keck/Low Resolution Imaging Spectrometer as well as Lyα, Si II, and Si III absorption obtained from the Hubble Space Telescope/Cosmic Origins Spectrograph. For the first time, we combine two independent models used to quantify the outflow properties for down-the-barrel and transverse absorption. We find that the modeled down-the-barrel deprojected outflow velocities range between V {sub dtb} = 45-255 km s{sup –1}. The transverse bi-conical outflow model, assuming constant-velocity flows perpendicular to the disk, requires wind velocities V {sub outflow} = 40-80 km s{sup –1} to reproduce the transverse Mg II absorption kinematics, which is consistent with the range of V {sub dtb}. The galaxy has a metallicity, derived from Hα and N II, of [O/H] = –0.21 ± 0.08, whereas the transverse absorption has [X/H] = –1.12 ± 0.02. The galaxy star formation rate is constrained between 4.6-15 M {sub ☉} yr{sup –1} while the estimated outflow rate ranges between 1.6-4.2 M {sub ☉} yr{sup –1} and yields a wind loading factor ranging between 0.1-0.9. The galaxy and gas metallicities, the galaxy-quasar sight-line geometry, and the down-the-barrel and transverse modeled outflow velocities collectively suggest that the transverse gas originates from ongoing outflowing material from the galaxy. The ∼1 dex decrease in metallicity from the base of the outflow to the outer halo suggests metal dilution of the gas by the time it reached 58 kpc.

  12. A Multiwavelength Study of Binary Quasars and Their Environments

    Science.gov (United States)

    Green, Paul J.; Myers, Adam D.; Barkhouse, Wayne A.; Aldcroft, Thomas L.; Trichas, Markos; Richards, Gordon T.; Ruiz, Ángel; Hopkins, Philip F.

    2011-12-01

    We present Chandra X-ray imaging and spectroscopy for 14 quasars in spatially resolved pairs targeted as part of a complete sample of binary quasars with small transverse separations drawn from Sloan Digital Sky Survey (SDSSDR6) photometry. We measure the X-ray properties of all 14 QSOs, and study the distribution of X-ray and optical-to-X-ray power-law indices in these binary quasars. We find no significant difference when compared with large control samples of isolated quasars, true even for SDSS J1254+0846, discussed in detail in a companion paper, which clearly inhabits an ongoing, pre-coalescence galaxy merger showing obvious tidal tails. We present infrared photometry from our observations with SAO Wide-field InfraRed Camera at the MMT, and from the Wide-field Infrared Survey Explorer Preliminary Data Release, and fit simple spectral energy distributions to all 14 QSOs. We find preliminary evidence that substantial contributions from star formation are required, but possibly no more so than for isolated X-ray-detected QSOs. Sensitive searches of the X-ray images for extended emission and the optical images for optical galaxy excess show that these binary QSOs—expected to occur in strong peaks of the dark matter distribution—are not preferentially found in rich cluster environments. While larger binary QSO samples with richer far-IR and submillimeter multiwavelength data might better reveal signatures of merging and triggering, optical color selection of QSO pairs may be biased against such signatures. X-ray and/or variability selection of QSO pairs, while challenging, should be attempted. We present in an Appendix a primer on X-ray flux and luminosity calculations.

  13. Quasar bolometric corrections: theoretical considerations

    CERN Document Server

    Nemmen, Rodrigo S

    2010-01-01

    Bolometric corrections based on the optical-to-ultraviolet continuum spectrum of quasars are widely used to quantify their radiative output, although such estimates are affected by a myriad of uncertainties, such as the generally unknown line-of-sight angle to the central engine. In order to shed light on these issues, we investigate the state-of-the-art models of Hubeny et al. that describe the continuum spectrum of thin accretion discs and include relativistic effects. We explore the bolometric corrections as a function of mass accretion rates, black hole masses and viewing angles, restricted to the parameter space expected for type-1 quasars. We find that a nonlinear relationship log L_bol=A + B log(lambda L_lambda) with B<=0.9 is favoured by the models and becomes tighter as the wavelength decreases. We calculate from the model the bolometric corrections corresponding to the wavelengths lambda = 1450A, 3000A and 5100A. In particular, for lambda=3000A we find A=9.24 +- 0.77 and B=0.81 +- 0.02. We demons...

  14. Updating quasar bolometric luminosity corrections

    CERN Document Server

    Runnoe, Jessie C; Shang, Zhaohui

    2012-01-01

    Bolometric corrections are used in quasar studies to quantify total energy output based on a measurement of a monochromatic luminosity. First, we enumerate and discuss the practical difficulties of determining such corrections, then we present bolometric luminosities between 1 \\mu m and 8 keV rest frame and corrections derived from the detailed spectral energy distributions of 63 bright quasars of low to moderate redshift (z = 0.03-1.4). Exploring several mathematical fittings, we provide practical bolometric corrections of the forms L_iso=\\zeta \\lambda L_{\\lambda} and log(L_iso)=A+B log(\\lambda L_{\\lambda}) for \\lambda= 1450, 3000, and 5100 \\AA, where L_iso is the bolometric luminosity calculated under the assumption of isotropy. The significant scatter in the 5100 \\AA\\ bolometric correction can be reduced by adding a first order correction using the optical slope, \\alpha_\\lambda,opt. We recommend an adjustment to the bolometric correction to account for viewing angle and the anisotropic emission expected fr...

  15. Molecular Outflows: Explosive versus Protostellar

    Science.gov (United States)

    Zapata, Luis A.; Schmid-Burgk, Johannes; Rodríguez, Luis F.; Palau, Aina; Loinard, Laurent

    2017-02-01

    With the recent recognition of a second, distinctive class of molecular outflows, namely the explosive ones not directly connected to the accretion–ejection process in star formation, a juxtaposition of the morphological and kinematic properties of both classes is warranted. By applying the same method used in Zapata et al., and using 12CO(J = 2-1) archival data from the Submillimeter Array, we contrast two well-known explosive objects, Orion KL and DR21, to HH 211 and DG Tau B, two flows representative of classical low-mass protostellar outflows. At the moment, there are only two well-established cases of explosive outflows, but with the full availability of ALMA we expect that more examples will be found in the near future. The main results are the largely different spatial distributions of the explosive flows, consisting of numerous narrow straight filament-like ejections with different orientations and in almost an isotropic configuration, the redshifted with respect to the blueshifted components of the flows (maximally separated in protostellar, largely overlapping in explosive outflows), the very-well-defined Hubble flow-like increase of velocity with distance from the origin in the explosive filaments versus the mostly non-organized CO velocity field in protostellar objects, and huge inequalities in mass, momentum, and energy of the two classes, at least for the case of low-mass flows. Finally, all the molecular filaments in the explosive outflows point back to approximately a central position (i.e., the place where its “exciting source” was located), contrary to the bulk of the molecular material within the protostellar outflows.

  16. Halo Occupation Distribution of Infrared Selected Quasars

    CERN Document Server

    Mitra, Kaustav

    2016-01-01

    We perform a Halo Occupation Distribution (HOD) modeling of the projected two-point correlation function (2PCF) of quasars that are observed in the Wide-field Infrared Survey Explorer (WISE) telescope with counter-parts in the Sloan Digital Sky Survey (SDSS) Data Release (DR)-8 quasar catalog at a median redshift of $z\\sim 1.04 (\\pm 0.58)$. Using a four parameter HOD model we derive the host mass scales of WISE selected quasars. Our results show that the median halo masses of central and satellite quasars lie in the range $M_{\\mathrm{cen}} = (5 \\pm 1.0) \\times 10^{12} M_{\\odot}$ and $M_{\\mathrm{sat}} = 8 (^{+7.8} _{-4.8}) \\times 10^{13} M_{\\odot}$, respectively. The derived satellite fraction is $f_{\\mathrm{sat}}= 5.5 (^{+35} _{-5.0})\\times 10^{-3}$. Previously Richardson et al.\\ used the SDSS DR7 quasar clustering data to obtain the halo mass distributions of $z\\sim 1.4$ quasars. Our results on the HOD of central quasars are in excellent agreement with Richardson et al.\\ but the host mass scale of satellite ...

  17. In Search of Quasar Host Galaxies

    Science.gov (United States)

    Young, Jason; Eracleous, M.; Gronwall, C.; Shemmer, O.; Netzer, H.; Sturm, E.; Ciardullo, R.

    2011-01-01

    We present a study of the morphology and intensity of star formation in the host galaxies of eight Palomar-Green quasars using observations with the Hubble Space Telescope. Accretion-powered and star formation activity have been shown to coincide, motivating us to search for the star-forming regions in the host galaxies of quasars and to determine the star-formation rates. In this work we use calibrated narrow band emission line (H-beta and Pa-alpha) WFPC2 and NICMOS images as maps for total star formation rate. The main challenge in imaging quasar host galaxies is the separation of the quasar light from the galaxy light, especially in the case of z approximately 0.1 quasars in WFPC2 images where the PSF radius closely matches the expected host scale radius. To this this end we present a novel technique for image decomposition and subtraction of quasar light, which we have validated through extensive simulations using artificial quasar+galaxy images. The other significant challenge in mapping and measuring star forming regions is correcting for extinction, which we address using extinction maps created from the Pa-alpha/H-beta ratio. To determine the source of excitation, we utilize H-beta along with [OIII]5007 and [OII]3727 images in diagnostic line ratio (BPT) diagrams. We detect extended line emission in our targets on scales of order 1-2 kpc. A preliminary analysis suggests star formation rates of order 10 solar masses per year.

  18. Quasar Proximity Zones and Patchy Reionization

    CERN Document Server

    Lidz, A; Zaldarriaga, M; Hernquist, L; Dutta, S; Lidz, Adam; Quinn, Matthew Mc; Zaldarriaga, Matias; Hernquist, Lars; Dutta, Suvendra

    2007-01-01

    Lyman-alpha forest absorption spectra towards quasars at z ~ 6 show regions of enhanced transmission close to their source. Several authors have argued that the apparently small sizes of these regions indicate that quasar ionization fronts at z >~ 6 expand into a largely or partly neutral intergalactic medium (IGM). Assuming that the typical region in the IGM is reionized by z <= 6, as is suggested by Ly-a forest observations, we argue that at {\\em least} 50% of the volume of the IGM was reionized before the highest redshift quasars turned on. Further, even if the IGM is as much as 50% neutral at quasar turn-on, the quasars are likely born into large galaxy-generated HII regions. The HII regions during reionization are themselves clustered, and using radiative transfer simulations, we find that long skewers through the IGM towards quasar progenitor halos pass entirely through ionized bubbles, even when the IGM is half neutral. These effects have been neglected in most previous analyses of quasar proximity ...

  19. Moderate resolution spectrophotometry of high redshift quasars

    Science.gov (United States)

    Schneider, Donald P.; Schmidt, Maarten; Gunn, James E.

    1991-01-01

    A uniform set of photometry and high signal-to-noise moderate resolution spectroscopy of 33 quasars with redshifts larger than 3.1 is presented. The sample consists of 17 newly discovered quasars (two with redshifts in excess of 4.4) and 16 sources drawn from the literature. The objects in this sample have r magnitudes between 17.4 and 21.4; their luminosities range from -28.8 to -24.9. Three of the 33 objects are broad absorption line quasars. A number of possible high redshift damped Ly-alpha systems were found.

  20. Merging Galaxies Create a Binary Quasar

    Science.gov (United States)

    2010-02-01

    Astronomers have found the first clear evidence of a binary quasar within a pair of actively merging galaxies. Quasars are the extremely bright centers of galaxies surrounding super-massive black holes, and binary quasars are pairs of quasars bound together by gravity. Binary quasars, like other quasars, are thought to be the product of galaxy mergers. Until now, however, binary quasars have not been seen in galaxies that are unambiguously in the act of merging. But images of a new binary quasar from the Carnegie Institution's Magellan telescope in Chile show two distinct galaxies with "tails" produced by tidal forces from their mutual gravitational attraction. "This is really the first case in which you see two separate galaxies, both with quasars, that are clearly interacting," says Carnegie astronomer John Mulchaey who made observations crucial to understanding the galaxy merger. Most, if not all, large galaxies, such as our galaxy the Milky Way, host super-massive black holes at their centers. Because galaxies regularly interact and merge, astronomers have assumed that binary super-massive black holes have been common in the Universe, especially during its early history. Black holes can only be detected as quasars when they are actively accreting matter, a process that releases vast amounts of energy. A leading theory is that galaxy mergers trigger accretion, creating quasars in both galaxies. Because most such mergers would have happened in the distant past, binary quasars and their associated galaxies are very far away and therefore difficult for most telescopes to resolve. The binary quasar, labeled SDSS J1254+0846, was initially detected by the Sloan Digital Sky Survey, a large scale astronomical survey of galaxies and over 120,000 quasars. Further observations by Paul Green of the Harvard-Smithsonian Center for Astrophysics and colleagues* using NASA's Chandra's X-ray Observatory and telescopes at Kitt Peak National Observatory in Arizona and Palomar

  1. The response of relativistic outflowing gas to the inner accretion disk of a black hole.

    Science.gov (United States)

    Parker, Michael L; Pinto, Ciro; Fabian, Andrew C; Lohfink, Anne; Buisson, Douglas J K; Alston, William N; Kara, Erin; Cackett, Edward M; Chiang, Chia-Ying; Dauser, Thomas; De Marco, Barbara; Gallo, Luigi C; Garcia, Javier; Harrison, Fiona A; King, Ashley L; Middleton, Matthew J; Miller, Jon M; Miniutti, Giovanni; Reynolds, Christopher S; Uttley, Phil; Vasudevan, Ranjan; Walton, Dominic J; Wilkins, Daniel R; Zoghbi, Abderahmen

    2017-03-01

    The brightness of an active galactic nucleus is set by the gas falling onto it from the galaxy, and the gas infall rate is regulated by the brightness of the active galactic nucleus; this feedback loop is the process by which supermassive black holes in the centres of galaxies may moderate the growth of their hosts. Gas outflows (in the form of disk winds) release huge quantities of energy into the interstellar medium, potentially clearing the surrounding gas. The most extreme (in terms of speed and energy) of these-the ultrafast outflows-are the subset of X-ray-detected outflows with velocities higher than 10,000 kilometres per second, believed to originate in relativistic (that is, near the speed of light) disk winds a few hundred gravitational radii from the black hole. The absorption features produced by these outflows are variable, but no clear link has been found between the behaviour of the X-ray continuum and the velocity or optical depth of the outflows, owing to the long timescales of quasar variability. Here we report the observation of multiple absorption lines from an extreme ultrafast gas flow in the X-ray spectrum of the active galactic nucleus IRAS 13224-3809, at 0.236 ± 0.006 times the speed of light (71,000 kilometres per second), where the absorption is strongly anti-correlated with the emission of X-rays from the inner regions of the accretion disk. If the gas flow is identified as a genuine outflow then it is in the fastest five per cent of such winds, and its variability is hundreds of times faster than in other variable winds, allowing us to observe in hours what would take months in a quasar. We find X-ray spectral signatures of the wind simultaneously in both low- and high-energy detectors, suggesting a single ionized outflow, linking the low- and high-energy absorption lines. That this disk wind is responding to the emission from the inner accretion disk demonstrates a connection between accretion processes occurring on very different

  2. Quasars Probing Quasars IV: Joint Constraints on the Circumgalactic Medium from Absorption and Emission

    CERN Document Server

    Hennawi, Joseph F

    2013-01-01

    We have constructed a sample of 29 close projected quasar pairs where the background quasar spectrum reveals absorption from optically thick HI gas associated with the foreground quasar. These unique sightlines allow us to study the quasar circumgalactic medium (CGM) in absorption and emission simultaneously, because the background quasar pinpoints large concentrations of gas where Ly-a emission, resulting from quasar-powered fluorescence, resonant Ly-a scattering, and/or cooling radiation, is expected. A sensitive slit-spectroscopic search (1-sigma limits of SB_Lya ~= 3e-18 erg/s/cm^2/arcsec^2) for diffuse Ly-a emission in the environments of the foreground quasars is conducted. We fail to detect large-scale ~ 100 kpc Ly-a emission, either at the location of the optically thick absorbers or in the foreground quasar halos, in all cases except a single system. We interpret these non-detections as evidence that the gas detected in absorption is shadowed from the quasar UV radiation due to obscuration effects, w...

  3. A quasar companion to the puzzling quasar SDSS J0927+2943

    OpenAIRE

    Decarli, R.; Falomo, R.; Treves, A.; Barattini, M

    2010-01-01

    We report the discovery of a quasar close to SDSS J0927+2943 (z = 0.713), which is a massive binary / recoiling black hole candidate. The companion quasar is at a projected distance of 125 h_70^{-1} kpc and exhibits a radial velocity difference of ~1400 km/s with respect to the known quasar. We discuss the nature of this peculiar quasar pair and the properties of its environment. We propose that the overall system is caught in the process of ongoing structure formation.

  4. Disk-driven rotating bipolar outflow in Orion Source I

    Science.gov (United States)

    Hirota, Tomoya; Machida, Masahiro N.; Matsushita, Yuko; Motogi, Kazuhito; Matsumoto, Naoko; Kim, Mi Kyoung; Burns, Ross A.; Honma, Mareki

    2017-07-01

    One of the outstanding problems in star formation theory concerns the transfer of angular momentum so that mass can accrete onto a newly born young stellar object (YSO). From a theoretical standpoint, outflows and jets are predicted to play an essential role in the transfer of angular momentum 1,2,3,4 and their rotations have been reported for both low- 5 and high-mass 6,7 YSOs. However, little quantitative discussion on outflow launching mechanisms has been presented for high-mass YSOs due to a lack of observational data. Here we present a clear signature of rotation in the bipolar outflow driven by Orion Source I, a high-mass YSO candidate, using the Atacama Large Millimeter/Submillimeter Array (ALMA). A rotational transition of silicon monoxide (Si18O) reveals a velocity gradient perpendicular to the outflow axis, which is consistent with that of the circumstellar disk traced by a high excitation water line. The launching radii and outward velocity of the outflow are estimated to be >10 au and 10 km s-1, respectively. These parameters rule out the possibility that the observed outflow is produced by the entrainment of a high-velocity jet 8 , and that contributions from the stellar wind 9 or X-wind 10 , which have smaller launching radii, are significant in the case of Source I. Thus these results provide convincing evidence of a rotating outflow directly driven by the magneto-centrifugal disk wind launched by a high-mass YSO candidate 6,11 .

  5. Protostellar Outflows in L1340

    CERN Document Server

    Walawender, Josh; Smutko, Michael; O'Linger-Luscusk, JoAnn; Moriarty-Schieven, Gerald

    2016-01-01

    We have searched the L1340 A, B, and C clouds for shocks from protostellar outflows using the H$_2$ 2.122 $\\mu$m near-IR line as a shock tracer. Substantial outflow activity has been found in each of the three regions of the cloud (L1340 A, L1340 B, & L1340 C). We find 42 distinct shock complexes (16 in L1340 A, 11 in L1340 B, and 15 in L1340 C). We were able to link 17 of those shock complexes in to 12 distinct outflows and identify candidate source stars for each. We examine the properties (A$_{V}$, T$_{bol}$, and L$_{bol}$) of the source protostars and compare that to the properties of the general population of Class 0/I and flat SED protostars and find that there is an indication, albeit at low statistical significance, that the outflow driving protostars are drawn from a population with lower A$_{V}$, higher L$_{bol}$, and lower T$_{bol}$ than the general population of protostars.

  6. Molecular outflows in starburst nuclei

    CERN Document Server

    Roy, Arpita; Sharma, Prateek; Shchekinov, Yuri

    2016-01-01

    Recent observations have detected molecular outflows in a few nearby starburst nuclei. We discuss the physical processes at work in such an environment in order to outline a scenario that can explain the observed parameters of the phenomenon, such as the molecular mass, speed and size of the outflows. We show that outflows triggered by OB associations, with $N_{OB}\\ge 10^5$ (corresponding to a star formation rate (SFR)$\\ge 1$ M$_{\\odot}$ yr$^{-1}$ in the nuclear region), in a stratified disk with mid-plane density $n_0\\sim 200\\hbox{--}1000$ cm$^{-3}$ and scale height $z_0\\ge 200 (n_0/10^2 \\, {\\rm cm}^{-3})^{-3/5}$ pc, can form molecules in a cool dense and expanding shell. The associated molecular mass is $\\ge 10^7$ M$_\\odot$ at a distance of a few hundred pc, with a speed of several tens of km s$^{-1}$. We show that a SFR surface density of $10 \\le \\Sigma_{SFR} \\le 50$ M$_\\odot$ yr$^{-1}$ kpc$^{-2}$ favours the production of molecular outflows, consistent with observed values.

  7. On the origins of C IV absorption profile diversity in broad absorption line quasars

    CERN Document Server

    Baskin, Alexei; Hamann, Fred

    2015-01-01

    There is a large diversity in the C IV broad absorption line (BAL) profile among BAL quasars (BALQs). We quantify this diversity by exploring the distribution of the C IV BAL properties, FWHM, maximum depth of absorption and its velocity shift ($v_{\\rm md}$), using the SDSS DR7 quasar catalogue. We find the following: (i) Although the median C IV BAL profile in the quasar rest-frame becomes broader and shallower as the UV continuum slope ($\\alpha_{\\rm UV}$ at 1700-3000 A) gets bluer, the median individual profile in the absorber rest-frame remains identical, and is narrow (FWHM = 3500 km/s) and deep. Only 4 per cent of BALs have FWHM > 10,000 km/s. (ii) As the He II emission equivalent-width (EW) decreases, the distributions of FWHM and $v_{\\rm md}$ extend to larger values, and the median maximum depth increases. These trends are consistent with theoretical models in which softer ionizing continua reduce overionization, and allow radiative acceleration of faster BAL outflows. (iii) As $\\alpha_{\\rm UV}$ become...

  8. A Physical Model of FeLoBALs: Implications for Quasar Feedback

    CERN Document Server

    Faucher-Giguere, C -A; Murray, N

    2011-01-01

    Photoionization modeling of the low-ionization broad absorption lines of certain quasars, known as FeLoBALs, has recently revealed the number density of the wind absorbers and their distance from the central supermassive black hole. From these, the feedback efficiency of the quasars can in principle be derived. The implied properties of the FeLoBALs are, however, surprising, with the thickness of the absorbers relative to their distance from the black hole, Delta R/R, as small as ~10^-5. Such absorbers are unlikely to survive the journey from the supermassive black hole to their inferred location. We show that the observed FeLoBAL properties are readily explained if they are formed in situ in radiative shocks produced when a quasar blast wave impacts a moderately dense interstellar clump along the line of sight. This physical picture differs significantly from the thin shell approximation often assumed, and implies outflow rates, kinetic luminosities and momentum fluxes that differ correspondingly, in some ca...

  9. CIV Emission Line Properties and Systematic Trends in Quasar Black Hole Mass Estimates

    CERN Document Server

    Coatman, Liam; Banerji, Manda; Richards, Gordon T

    2016-01-01

    Black-hole masses are crucial to understanding the physics of the connection between quasars and their host galaxies and measuring cosmic black hole-growth. At high redshift, z > 2.1, black hole masses are normally derived using the velocity-width of the CIV broad emission line, based on the assumption that the observed velocity-widths arise from virial-induced motions. In many quasars, the CIV-emission line exhibits significant blue asymmetries (`blueshifts') with the line centroid displaced by up to thousands of km/s to the blue. These blueshifts almost certainly signal the presence of strong outflows, most likely originating in a disc wind. We have obtained near-infrared spectra, including the H$\\alpha$ emission line, for 19 luminous ($L_{Bol}$ = 46.5-47.5 erg/s) Sloan Digital Sky Survey quasars, at redshifts 2 2000 km/s, the velocity-widths appear to be dominated by non-virial motions. Black-hole masses, based on the full width at half maximum of the CIV-emission line, can be overestimated by a factor of...

  10. Outflow forces in intermediate mass star formation

    CERN Document Server

    van Kempen, T A; van Dishoeck, E F; Kristensen, L E; Belloche, A; Klaassen, P D; Leurini, S; Jose-Garcia, I San; Aykutalp, A; Choi, Y; Endo, A; Frieswijk, W; Harsono, D; Karska, A; Koumpia, E; van der Marel, N; Nagy, Z; Perez-Beaupuits, J P; Risacher, C; van Weeren, R J; Wyrowski, F; Yildiz, U A; Guesten, R; Boland, W; Baryshev, A

    2015-01-01

    Intermediate mass protostarsprovide a bridge between theories of low- and high-mass star formation. Emerging molecular outflows can be used to determine the influence of fragmentation and multiplicity on protostellar evolution through the correlation of outflow forces of intermediate mass protostars with the luminosity. The aim of this paper is to derive outflow forces from outflows of six intermediate mass protostellar regions and validate the apparent correlation between total luminosity and outflow force seen in earlier work, as well as remove uncertainties caused by different methodology. By comparing CO 6--5 observations obtained with APEX with non-LTE radiative transfer model predictions, optical depths, temperatures, densities of the gas of the molecular outflows are derived. Outflow forces, dynamical timescales and kinetic luminosities are subsequently calculated. Outflow parameters, including the forces, were derived for all sources. Temperatures in excess of 50 K were found for all flows, in line wi...

  11. Uncovering the Outflow Driven by the Brown Dwarf LS-RCr A1: H-alpha as a Tracer of Outflow Activity in Brown Dwarfs

    CERN Document Server

    Whelan, E T; Bacciotti, F

    2009-01-01

    It is now apparent that classical T Tauri-like outflows commonly accompany the formation of young brown dwarfs. To date two optical outflows have been discovered and results presented in this paper increase this number to three. Using spectro-astrometry the origin of the LS-RCrA 1 forbidden emission lines in a blue-shifted outflow is confirmed. The non-detection of the red-shifted component of the outflow in forbidden lines, along with evidence for some separation between low and high velocity outflow components, do not support the hypothesis that LS-RCrA 1 has an edge-on accretion disk. The key result of this analysis is the discovery of an outflow component to the H-alpha line. The H-alpha line profile has blue and red-shifted features in the wings which spectro-astrometry reveals to also originate in the outflow. The discovery that H-alpha emission in BDs can have a significant contribution from an outflow suggests the use of H-alpha line widths as a proxy of mass accretion in BDs is not clear-cut. This me...

  12. Quasars as tracers of cosmic flows

    CERN Document Server

    Modzelewska, J; Bilicki, M; Hryniewicz, K; Krupa, M; Petrogalli, F; Pych, W; Kurcz, A; Udalski, A

    2014-01-01

    Quasars, as the most luminous persistent sources in the Universe, have broad applications for cosmological studies. In particular, they can be employed to directly measure the expansion history of the Universe, similarly to SNe Ia. The advantage of quasars is that they are numerous, cover a broad range of redshifts, up to $z = 7$, and do not show significant evolution of metallicity with redshift. The idea is based on the relation between the time delay of an emission line and the continuum, and the absolute monochromatic luminosity of a quasar. For intermediate redshift quasars, the suitable line is Mg II. Between December 2012 and March 2014, we performed five spectroscopic observations of the QSO CTS C30.10 ($z = 0.900$) using the South African Large Telesope (SALT), supplemented with photometric monitoring, with the aim of determining the variability of the line shape, changes in the total line intensity and in the continuum. We show that the method is very promising.

  13. Local Ultraluminous Infrared Galaxies and Quasars

    CERN Document Server

    Veilleux, S

    2006-01-01

    This paper reviews the recent results from a comprehensive investigation of the most luminous mergers in the local universe, the ultraluminous infrared galaxies (ULIRGs) and the quasars. First, the frequency of occurrence and importance of black hole driven nuclear activity in ULIRGs are discussed using the latest sets of optical, near-infrared, mid-infrared, and X-ray spectra on these objects. Obvious trends with luminosity, infrared color, and morphology are pointed out. Next, the host galaxy properties of ULIRGs are described in detail and then compared with local quasar hosts and inactive spheroids. By and large, these data are consistent with the scenario where ULIRGs are intermediate-mass elliptical galaxies in formation and in the process of becoming moderate-luminosity optical quasars. The powerful galactic winds detected in many ULIRGs may help shed any excess gas during this transformation. However, this evolutionary scenario does not seem to apply to all ULIRGs and quasars: Ultraluminous infrared m...

  14. Quasars as probes of cosmological reionization

    CERN Document Server

    Mortlock, Daniel J

    2015-01-01

    Quasars are the most luminous non-transient sources in the epoch of cosmological reionization (i.e., which ended a billion years after the Big Bang, corresponding to a redshift of z ~ 5), and are powerful probes of the inter-galactic medium at that time. This review covers current efforts to identify high-redshift quasars and how they have been used to constrain the reionization history. This includes a full description of the various processes by which neutral hydrogen atoms can absorb/scatter ultraviolet photons, and which lead to the Gunn-Peterson effect, dark gap and dark pixel analyses, quasar near zones and damping wing absorption. Finally, the future prospects for using quasars as probes of reionization are described.

  15. Quasars as Extreme Case of Galaxies

    CERN Document Server

    Nasiri, S

    1999-01-01

    We introduce a phenomenological investigation of the evolution and large scale distribution of quasars using a modified version of the Field and Colgate gravitational contraction model for proto-galaxies. By studying the distribution of about 7000 quasars in 5 luminosity classes, it seems that, such a model is capable of solving the energy problem and discussing some of the observational properties of these objects. A sketch of luminosity function of the quasars and the normal galaxies shows a unified aspect for these objects. The large scale distribution of the quasars in the galactic coordinate shows the existence of filamentary structures and voids in the same sence that have been resolved by exploring the clusters of galaxies.

  16. New Discoveries Fill the Quasar Gap

    Science.gov (United States)

    Kohler, Susanna

    2017-04-01

    Quasars active and luminous galactic centers can be difficult to find at some high redshifts due to their camouflaging color. A team of scientists has now come up with a way to detect these distant monsters in spite of their disguise.Quasar CamouflageThe color track of quasars between 5 z 6 in the commonly used i z and r i bands. Each dot on the red line marks a 0.1 difference in redshift. The contours show the colors of M dwarfs, from early type to late type. Quasars at a redshift of 5.3 z 5.7 are clearly contaminated by M dwarfs, making them difficult to identify. [Adapted from Yang et al. 2017]One of the key ways we can study the early universe is by building a large sample of high-redshift quasars. In particular, we believe that reionization of the universe is just completing around z 6. Quasars near this redshift are crucial tools for probing the post-reionization epoch and exploring the evolution of the intergalactic medium, quasar evolution, and early supermassive black hole growth.But quasars at this redshift are difficult to detect! The problem is contamination: quasars at this distance are the same color in commonly used optical bands as cool M-dwarf stars. As a result, surveys searching for quasars have often just cut out that entire section of the color space in order to avoid this contamination.This means that theres a huge gap in our sample of quasars around z 5.5: of the more than 300,000 quasars known, only 30 have been found in the redshift range of 5.3 z 5.7.The addition of new colorcolor selection criteria using infrared bands (bottom two plots) allows the authors to differentiate quasars (blue) from M dwarfs (grey), which isnt possible when only the traditional optical colorcolor selection criteria are used (top plot). [Adapted from Yang et al. 2017]A New ApproachIn a recent publication led by Jinyi Yang (Peking University, China and Steward Observatory, University of Arizona), a team of scientists has demonstrated a new technique for finding

  17. Extremely Variable Quasars from CRTS and WISE

    Science.gov (United States)

    Stern, Daniel

    2017-08-01

    I will present deep dives on a few examples of highly variable quasars identified from the Catalina Real-Time Transient Survey (CRTS) and WISE/NEOWISE. In particular, I will focus on a CRTS-identified iron low-ionization broad absorption line (FeLoBAL) quasar which, over the past decade, has transformed into a more typical BAL quasar (Stern et al. 2017) and a WISE-identified quasar that has shut off in the past decade (Stern et al., in prep.). I will focus on what we learn about the physics of these systems from the multiwavelength imaging and spectroscopy. Given the pace of discovery, additional interesting examples are expected to be discovered before the conference.

  18. Starburst Galaxies: Outflows of Metals and Energy into the IGM

    CERN Document Server

    Strickland, David K; Ptak, Andrew; Schlegel, Eric; Tremonti, Christy; Tsuru, Takeshi; Tuellmann, Ralph; Zezas, Andreas

    2009-01-01

    What is the contribution of mass, metals and energy from starburst galaxies to the Intergalactic Medium? Starburst galaxies drive galactic-scale outflows or "superwinds" that may be responsible for removing metals from galaxies and polluting the Intergalactic Medium (IGM). In the last decade tremendous progress was made in mapping cool entrained gas in superwinds through UV/optical imaging and absorption line spectroscopy. These studies demonstrated that superwinds are ubiquitous in galaxies forming stars at high surface densities and that the most powerful starbursts can drive outflows near escape velocity. Theoretical models of galaxy evolution have begun to incorporate superwinds, using various ad-hoc prescriptions based on our knowledge of the cool gas. However, these efforts are fundamentally impeded by our lack of information about the hot phase of these outflows. The hot X-ray emitting phase of a superwind contains the majority of its energy and newly-synthesized metals, and given its high specific ene...

  19. Simulations of Metal Enrichment in Galaxy Clusters by AGN Outflows

    CERN Document Server

    Moll, R; Domainko, W; Kapferer, W; Mair, M; Van Kampen, E; Kronberger, T; Kimeswenger, S; Ruffert, M

    2006-01-01

    We assess the importance of AGN outflows with respect to the metal enrichment of the intracluster medium (ICM) in galaxy clusters. We use combined N-body and hydrodynamic simulations, along with a semi-numerical galaxy formation and evolution model. Using assumptions based on observations, we attribute outflows of metal-rich gas initiated by AGN activity to a certain fraction of our model galaxies. The gas is added to the model ICM, where the evolution of the metallicity distribution is calculated by the hydrodynamic simulations. For the parameters describing the AGN content of clusters and their outflow properties, we use the observationally most favorable values. We find that AGNs have the potential to contribute significantly to the metal content of the ICM or even explain the complete abundance, which is typically ~0.5 Z_sun in core regions. Furthermore, the metals end up being inhomogeneously distributed, in accordance with observations.

  20. Numerical simulations of quasar absorbers

    CERN Document Server

    Theuns, T

    2005-01-01

    The physical state of the intergalactic medium can be probed in great detail with the intervening absorption systems seen in quasar spectra. The properties of the Hydrogen absorbers depend on many cosmological parameters, such as the matter-power spectrum, reionisation history, ionising background and the nature of the dark matter. The spectra also contain metal lines, which can be used to constrain the star formation history and the feedback processes acting in large and small galaxies. Simulations have been instrumental in investigating to what extent these parameters can be unambiguously constrained with current and future data. This paper is meant as an introduction to this subject, and reviews techniques and methods for simulating the intergalactic medium.

  1. QUASARS PROBING QUASARS. IV. JOINT CONSTRAINTS ON THE CIRCUMGALACTIC MEDIUM FROM ABSORPTION AND EMISSION

    Energy Technology Data Exchange (ETDEWEB)

    Hennawi, Joseph F.; Prochaska, J. Xavier, E-mail: xavier@ucolick.org [Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany)

    2013-03-20

    We have constructed a sample of 29 close projected quasar pairs where the background quasar spectrum reveals absorption from optically thick H I gas associated with the foreground quasar. These unique sightlines allow us to study the quasar circumgalactic medium (CGM) in absorption and emission simultaneously, because the background quasar pinpoints large concentrations of gas where Ly{alpha} emission, resulting from quasar-powered fluorescence, resonant Ly{alpha} scattering, and/or cooling radiation, is expected. A sensitive search (1{sigma} surface-brightness limits of SB{sub Ly{alpha}}{approx_equal}3 Multiplication-Sign 10{sup -18} erg s{sup -1} cm{sup -2} arcsec{sup -2}) for diffuse Ly{alpha} emission in the environments of the foreground (predominantly radio-quiet) quasars is conducted using Gemini/GMOS and Keck/LRIS slit spectroscopy. We fail to detect large-scale {approx}100 kpc Ly{alpha} emission, either at the location of the optically thick absorbers or in the foreground quasar halos, in all cases except a single system. We interpret these non-detections as evidence that the gas detected in absorption is shadowed from the quasar UV radiation due to obscuration effects, which are frequently invoked in unified models of active galactic nuclei. Small-scale R {approx}< 50 kpc extended Ly{alpha} nebulosities are detected in 34% of our sample, which are likely the high-redshift analogs of the extended emission-line regions (EELRs) commonly observed around low-redshift (z < 0.5) quasars. This may be fluorescent recombination radiation from a population of very dense clouds with a low covering fraction illuminated by the quasar. We also detect a compact high rest-frame equivalent width (W{sub Ly{alpha}} > 50 A) Ly{alpha}-emitter with luminosity L{sub Ly{alpha}} = 2.1 {+-} 0.32 Multiplication-Sign 10{sup 41} erg s{sup -1} at small impact parameter R = 134 kpc from one foreground quasar, and argue that it is more likely to result from quasar-powered fluorescence

  2. Dust in the wind II: Polarization imaging from disk-born outflows

    CERN Document Server

    Marin, F

    2013-01-01

    In this second research note of a series of two, we aim to map the polarized flux emerging from a disk-born, dusty outflow as it was prescribed by Elvis (2000). His structure for quasars was achieved to unify the emission and absorption features observed in active galactic nuclei (AGN) and can be used as an alternative scenario to the typical dusty torus that is extensively used to account for AGN circumnuclear obscuration. Using Monte Carlo radiative transfer simulations, we model an obscuring outflow arising from an emitting accretion disk and examine the resulting polarization degree, polarization angle and polarized flux. Polarization cartography reveals that a disk-born outflow has a similar torus morphology in polar viewing angles, with bright polarized fluxes reprocessed onto the wind funnel. At intermediate and edge-on inclinations, the model is rather close to a double-conical wind, with higher fluxes in the cone bases. It indicates that the optically thick outflow is not efficient enough to avoid ra...

  3. Electron-Positron Outflows from $\\gamma$-Ray Emitting Accretion Discs

    CERN Document Server

    Beloborodov, A M

    1999-01-01

    An electron-positron atmosphere is inevitably created around a black hole accretion disc whose spectrum extends to MeV energies. Pairs created in photon-photon collisions outside the disc are blown away by soft radiation (which dominates the bolometric luminosity of the disc) and form a semi-relativistic outflow. We simulate numerically the conversion of the MeV radiation into a vertical e+- outflow above a disc-like source. The outflowing e+- plasma becomes optically thick to Thomson scattering if the compactness of the gamma-ray source exceeds 30. The scattering by e+- then collimates the bulk of soft radiation along the disc axis, and the apparent bolometric luminosity of the disc depends strongly on its inclination to the line of sight. The anisotropic central emission may account for the lack of Fe K-alpha lines in the X-ray spectra of bright radio-quiet quasars. The scattering in e+- outflows may also explain the orientation of optical polarization in non-blazar active galactic nuclei.

  4. Expanding space, quasars and St. Augustine's fireworks

    CERN Document Server

    Chashchina, O I

    2014-01-01

    An attempt is made to explain time non-dilation allegedly observed in quasar light curves. The explanation is based on the assumption that quasar black holes are, in some sense, foreign for our Friedmann-Robertson-Walker universe and do not participate in the Hubble flow. Although at first sight such a weird explanation requires unreasonably fine-tuned Big Bang initial conditions, we find a natural justification for it using the Milne cosmological model as an inspiration.

  5. Dust in the Quasar Wind (Artist Concept)

    Science.gov (United States)

    2007-01-01

    Dusty grains -- including tiny specks of the minerals found in the gemstones peridot, sapphires and rubies -- can be seen blowing in the winds of a quasar, or active black hole, in this artist's concept. The quasar is at the center of a distant galaxy. Astronomers using NASA's Spitzer Space Telescope found evidence that such quasar winds might have forged these dusty particles in the very early universe. The findings are another clue in an ongoing cosmic mystery: where did all the dust in our young universe come from? Dust is crucial for efficient star formation as it allows the giant clouds where stars are born to cool quickly and collapse into new stars. Once a star has formed, dust is also needed to make planets and living creatures. Dust has been seen as far back as when the universe was less than a tenth of its current age, but how did it get there? Most dust in our current epoch forms in the winds of evolved stars that did not exist when the universe was young. Theorists had predicted that winds from quasars growing in the centers of distant galaxies might be a source of this dust. While the environment close to a quasar is too hot for large molecules like dust grains to survive, dust has been found in the cooler, outer regions. Astronomers now have evidence that dust is created in these outer winds. Using Spitzer's infrared spectrograph instrument, scientists found a wealth of dust grains in a quasar called PG2112+059 located at the center of a galaxy 8 billion light-years away. The grains - including corundum (sapphires and rubies); forsterite (peridot); and periclase (naturally occurring in marble) - are not typically found in galaxies without quasars, suggesting they might have been freshly formed in the quasar's winds.

  6. Expanding Space, Quasars and St. Augustine's Fireworks

    Science.gov (United States)

    Chashchina, Olga; Silagadze, Zurab

    2015-10-01

    An attempt is made to explain time non-dilation allegedly observed in quasar light curves. The explanation is based on the assumption that quasar black holes are, in some sense, foreign for our Friedmann-Robertson-Walker universe and do not participate in the Hubble flow. Although at first sight such a weird explanation requires unreasonably fine-tuned Big Bang initial conditions, we find a natural justification for it using the Milne cosmological model as an inspiration.

  7. Sensitive Radio Survey of Obscured Quasar Candidates

    CERN Document Server

    Alexandroff, Rachael M; van Velzen, Sjoert; Greene, Jenny E; Strauss, Michael A

    2016-01-01

    We study the radio properties of moderately obscured quasars over a range of redshifts to understand the role of radio activity in accretion using the Jansky Very Large Array (JVLA) at 6.0GHz and 1.4GHz. Our z~2.5 sample consists of optically-selected obscured quasar candidates, all of which are radio-quiet, with typical radio luminosities of $\

  8. Rest-frame Optical Properties of Luminous 1.5Quasars: the Hbeta-[OIII] Region

    CERN Document Server

    Shen, Yue

    2015-01-01

    We study the rest-frame optical properties of 74 luminous (L_bol=10^46.2-48.2 erg/s), 1.5quasars with near-IR (JHK) slit spectroscopy. Systemic redshifts based on the peak of the [OIII]5007 line reveal that redshift estimates from the rest-frame UV broad emission lines (mostly MgII) are intrinsically uncertain by ~ 200 km/s (measurement errors accounted for). The overall full-width-at-half-maximum of the narrow [OIII] line is ~ 1000 km/s on average. A significant fraction of the total [OIII] flux (~ 40%) is in a blueshifted wing component with a median velocity offset of ~ 700 km/s, indicative of ionized outflows within a few kpc from the nucleus; we do not find evidence of significant [OIII] flux beyond ~ 10 kpc in our slit spectroscopy. The [OIII] line is noticeably more asymmetric and weaker than that in typical less luminous low-z quasars. However, when matched in quasar continuum luminosity, low-z quasars have similar [OIII] profiles and strengths as these high-z systems. Therefor...

  9. Ionization state of cosmic hydrogen by early stars and quasars

    Institute of Scientific and Technical Information of China (English)

    Xiao-Chun Mao

    2009-01-01

    Cosmic hydrogen is reionized and maintained in its highly ionized state by the ultraviolet emission attributed to an early generation of stars and quasars. The Lyα opacity observed in absorption spectra of high-redshift quasars permits more stringent constraints on the ionization state of cosmic hydrogen. Based on density perturbation and structure formation theory, we develop an analytic model to trace the evolution of the ionization state in the post-overlap epoch of reionization, in which the bias factor is taken into ac-count. For quasars, we represent an improved luminosity function by utilizing a hybrid approach for the halo formation rate that is in reasonable agreement with the published measurements at 2 z 6. Comparison with the classic Press-Schechter mass function of dark matter halos, we demonstrate that the biased mass distribution indeed enhances star formation efficiency in the overdense environment by more than 25 per cent following the overlap of ionized bubbles. In addition, an alternative way is introduced to derive robust estimates of the mean free path for ionizing photons. In our model, star-forming galax-ies are likely to dominate the ionizing background radiation beyond z = 3, and quasars contribute equally above a redshift of z ~ 2.5. From 5 ≤ z ≤ 6, the lack of evolution in photoionization rate can thus be explained by the relatively flat evolution in star formation efficiency, although the mean free path of ionizing photons increases rapidly. Moreover, in the redshift interval z ~ 2 - 6, the expected mean free path and Gunn-Peterson optical depth obviously evolve by a factor of ~ 500 and ~ 50 respectively. We find that the rel-ative values of critical overdensities for hydrogen ionization and collapse could be 430% at z ≈ 2 and 2% at z ≈ 6, suggesting a rapid overlap process in the overdense regions around instant quasars following reionization. We further illustrate that the absolute esti-mates of the fraction of neutral

  10. Survey For Very High-Redshift Quasars

    Science.gov (United States)

    Lemley, S.; MacAlpine, G.

    1997-12-01

    I will present the results from the deep, three color survey for very high redshift quasars. The survey involved direct imaging through Gunn gri filters using a 2048 x 2048 STIS ccd chip and Cerro Tololo's Curtis Scmidt Telescope. Quasar candidates in the range 4.0 < z < 5.4 were selected based on the detection of the Lyman alpha line and the strong drop in the spectrum blueward of this. Because of this response, quasars are clearly located away from the stellar locus on g - r vs. r - i diagrams. Quasar candidates in this redshift range have large values of g - r and small values of r - i. To confirm the candidates as quasars, the multi-fiber spectroscope Hydra, located on the WIYN telescope, was used. To date, spectral confirmation has been completed for ten degrees out of the approximately fifteen square degress of survey area. Several quasars were discovered, and I will present their spectra and information on the viability of this technique.

  11. The environment of low redshift quasar pairs

    CERN Document Server

    Sandrinelli, Angela; Treves, Aldo; Farina, Emanuele Paolo; Uslenghi, Michela

    2014-01-01

    We investigate the properties of the galaxy environment of a sample of 14 low redshift (z $<$ 0.85) quasar physical pairs extracted from SDSS DR10 archives. The pairs have a systemic radial velocity difference $\\Delta V_\\parallel \\leqslant$ 600 $km \\ s^{-1}$ (based on [OIII]5007 \\AA \\ line) and projected distance $ R_\\bot \\leqslant$ 600 kpc. The physical association of the pairs is statistically confirmed at a level of $\\sim$ 90 %. For most of the images of these quasars we are able to resolve their host galaxies that turn out to be on average similar to those of quasars not in pairs. We also found that quasars in a pair are on average in region of modest galaxy overdensity extending up 0.5 Mpc from the QSO. This galaxy overdensity is indistinguishable from that of a homogeneous sample of isolated quasars at the same redshift and with similar host galaxy luminosity. These results, albeit derived from a small (but homogeneous) sample of objects, suggest that the rare activation of two quasars with small phy...

  12. QUASARS PROBING QUASARS. VI. EXCESS H I ABSORPTION WITHIN ONE PROPER Mpc OF z ∼ 2 QUASARS

    Energy Technology Data Exchange (ETDEWEB)

    Prochaska, J. Xavier; Cantalupo, Sebastiano; Lau, Marie Wingyee [Department of Astronomy and Astrophysics, UCO/Lick Observatory, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States); Hennawi, Joseph F.; Lee, Khee-Gan; Myers, Adam; Rubin, Kate H. R. [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69115 Heidelberg (Germany); Bovy, Jo [Institute for Advanced Study, Einstein Drive, Princeton, NJ 08540 (United States); Djorgovski, S. G. [California Institute of Technology, Pasadena, CA 91125 (United States); Ellison, Sara L. [Department of Physics and Astronomy, University of Victoria, Finnerty Road, Victoria, British Columbia V8P 1A1 (Canada); Martin, Crystal L. [Department of Physics, University of California, Santa Barbara, Santa Barbara, CA 93106 (United States); Simcoe, Robert A. [MIT-Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

    2013-10-20

    With close pairs of quasars at different redshifts, a background quasar sightline can be used to study a foreground quasar's environment in absorption. We use a sample of 650 projected quasar pairs to study the H I Lyα absorption transverse to luminous, z ∼ 2 quasars at proper separations of 30 kpc < R < 1 Mpc. In contrast to measurements along the line-of-sight, regions transverse to quasars exhibit enhanced H I Lyα absorption and a larger variance than the ambient intergalactic medium, with increasing absorption and variance toward smaller scales. Analysis of composite spectra reveals excess absorption characterized by a Lyα equivalent width profile W = 2.3 Å (R /100 kpc){sup –0.46}. We also observe a high (≅ 60%) covering factor of strong, optically thick H I absorbers (H I column N{sub H{sub I}}>10{sup 17.3} cm{sup -2}) at separations R < 200 kpc, which decreases to ∼20% at R ≅ 1 Mpc, but still represents a significant excess over the cosmic average. This excess of optically thick absorption can be described by a quasar-absorber cross-correlation function ξ{sub QA}(r) = (r/r{sub 0}){sup γ} with a large correlation length r{sub 0} = 12.5{sup +2.7}{sub -1.4} h{sup -1} Mpc (comoving) and γ=1.68{sup +0.14}{sub -0.30}. The H I absorption measured around quasars exceeds that of any previously studied population, consistent with quasars being hosted by massive dark matter halos M{sub halo} ≈ 10{sup 12.5} M{sub ☉} at z ∼ 2.5. The environments of these massive halos are highly biased toward producing optically thick gas, and may even dominate the cosmic abundance of Lyman limit systems and hence the intergalactic opacity to ionizing photons at z ∼ 2.5. The anisotropic absorption around quasars implies the transverse direction is much less likely to be illuminated by ionizing radiation than the line-of-sight.

  13. A Quasar Catalog with Simultaneous UV, Optical and X-ray Observations by Swift

    CERN Document Server

    Wu, Jian; Grupe, Dirk; Koch, Scott; Gelbord, Jonathan; Schneider, Donald P; Gronwall, Caryl; Wesolowski, Sarah; Porterfield, Blair L

    2012-01-01

    We have compiled a catalog of optically-selected quasars with simultaneous observations in UV/optical and X-ray bands by the Swift Gamma Ray Burst Explorer. Objects in this catalog are identified by matching the Swift pointings with the Sloan Digital Sky Survey Data Release 5 quasar catalog. The final catalog contains 843 objects, among which 637 have both UVOT and XRT observations and 354 of which are detected by both instruments. The overall X-ray detection rate is ~60% which rises to ~85% among sources with at least 10 ks of XRT exposure time. We construct the time-averaged spectral energy distribution for each of the 354 quasars using UVOT photometric measurements and XRT spectra. From model fits to these SEDs, we find that the big blue bump contributes about 0.3 dex to the quasar luminosity. We re-visit the alpha_ox-L_uv relation by selecting a clean sample with only type 1 radio-quiet quasars; the dispersion of this relation is reduced by at least 15% compared to studies that use non-simultaneous UV/opt...

  14. Evidence for two spatially separated UV continuum emitting regions in the Cloverleaf broad absorption line quasar

    CERN Document Server

    Sluse, D; Anguita, T; Braibant, L; Riaud, P

    2015-01-01

    Testing the standard Shakura-Sunyaev model of accretion is a challenging task because the central region of quasars where accretion takes place is unresolved with telescopes. The analysis of microlensing in gravitationally lensed quasars is one of the few techniques which can test this model, yielding to the measurement of the size and of the temperature profile of the accretion disc. We present spectroscopic observations of the gravitationally lensed broad absorption line quasar H1413+117, which reveal partial microlensing of the continuum emission that appears to originate from two separated regions, a microlensed region corresponding the compact accretion disc, and a non-microlensed region, more extended and contributing to at least 30\\% of the total UV-continuum flux. Because this extended continuum is occulted by the broad absorption line clouds, it is not associated to the host galaxy, but rather to light scattered in the neighbourhood of the central engine. We measure the amplitude of microlensing of t...

  15. Shining A Light On Galactic Outflows: Photo-Ionized Outflows

    CERN Document Server

    Chisholm, John; Leitherer, Claus; Chen, Yanmei; Wofford, Aida

    2016-01-01

    We study the ionization structure of galactic outflows in 37 nearby, star forming galaxies with the Cosmic Origins Spectrograph on the Hubble Space Telescope. We use the O I, Si II, Si III, and Si IV ultraviolet absorption lines to characterize the different ionization states of outflowing gas. We measure the equivalent widths, line widths, and outflow velocities of the four transitions, and find shallow scaling relations between them and galactic stellar mass and star formation rate. Regardless of the ionization potential, lines of similar strength have similar velocities and line widths, indicating that the four transitions can be modeled as a co-moving phase. The Si equivalent width ratios (e.g. Si IV/Si II) have low dispersion, and little variation with stellar mass; while ratios with O I and Si vary by a factor of 2 for a given stellar mass. Photo-ionization models reproduce these equivalent width ratios, while shock models under predict the relative amount of high ionization gas. The photo-ionization mo...

  16. The Final SDSS High-Redshift Quasar Sample of 52 Quasars at z>5.7

    CERN Document Server

    Jiang, Linhua; Fan, Xiaohui; Strauss, Michael A; Banados, Eduardo; Becker, Robert H; Bian, Fuyan; Farnsworth, Kara; Shen, Yue; Wang, Feige; Wang, Ran; Wang, Shu; White, Richard L; Wu, Jin; Wu, Xue-Bing; Yang, Jinyi; Yang, Qian

    2016-01-01

    We present the discovery of nine quasars at $z\\sim6$ identified in the Sloan Digital Sky Survey (SDSS) imaging data. This completes our survey of $z\\sim6$ quasars in the SDSS footprint. Our final sample consists of 52 quasars at $5.7quasars with $z_{\\rm AB}\\le20$ mag selected from 11,240 deg$^2$ of the SDSS single-epoch imaging survey (the main survey), 10 quasars with $20\\le z_{\\rm AB}\\le20.5$ selected from 4223 deg$^2$ of the SDSS overlap regions (regions with two or more imaging scans), and 13 quasars down to $z_{\\rm AB}\\approx22$ mag from the 277 deg$^2$ in Stripe 82. They span a wide luminosity range of $-29.0\\le M_{1450}\\le-24.5$. This well-defined sample is used to derive the quasar luminosity function (QLF) at $z\\sim6$. After combining our SDSS sample with two faint ($M_{1450}\\ge-23$ mag) quasars from the literature, we obtain the parameters for a double power-law fit to the QLF. The bright-end slope $\\beta$ of the QLF is well constrained to be $\\beta=-2.8\\pm0.2$. Due to the...

  17. The response of relativistic outflowing gas to the inner accretion disk of a black hole

    Science.gov (United States)

    Parker, Michael L.; Pinto, Ciro; Fabian, Andrew C.; Lohfink, Anne; Buisson, Douglas J. K.; Alston, William N.; Kara, Erin; Cackett, Edward M.; Chiang, Chia-Ying; Dauser, Thomas; De Marco, Barbara; Gallo, Luigi C.; Garcia, Javier; Harrison, Fiona A.; King, Ashley L.; Middleton, Matthew J.; Miller, Jon M.; Miniutti, Giovanni; Reynolds, Christopher S.; Uttley, Phil; Vasudevan, Ranjan; Walton, Dominic J.; Wilkins, Daniel R.; Zoghbi, Abderahmen

    2017-03-01

    The brightness of an active galactic nucleus is set by the gas falling onto it from the galaxy, and the gas infall rate is regulated by the brightness of the active galactic nucleus; this feedback loop is the process by which supermassive black holes in the centres of galaxies may moderate the growth of their hosts. Gas outflows (in the form of disk winds) release huge quantities of energy into the interstellar medium, potentially clearing the surrounding gas. The most extreme (in terms of speed and energy) of these—the ultrafast outflows—are the subset of X-ray-detected outflows with velocities higher than 10,000 kilometres per second, believed to originate in relativistic (that is, near the speed of light) disk winds a few hundred gravitational radii from the black hole. The absorption features produced by these outflows are variable, but no clear link has been found between the behaviour of the X-ray continuum and the velocity or optical depth of the outflows, owing to the long timescales of quasar variability. Here we report the observation of multiple absorption lines from an extreme ultrafast gas flow in the X-ray spectrum of the active galactic nucleus IRAS 13224‑3809, at 0.236 ± 0.006 times the speed of light (71,000 kilometres per second), where the absorption is strongly anti-correlated with the emission of X-rays from the inner regions of the accretion disk. If the gas flow is identified as a genuine outflow then it is in the fastest five per cent of such winds, and its variability is hundreds of times faster than in other variable winds, allowing us to observe in hours what would take months in a quasar. We find X-ray spectral signatures of the wind simultaneously in both low- and high-energy detectors, suggesting a single ionized outflow, linking the low- and high-energy absorption lines. That this disk wind is responding to the emission from the inner accretion disk demonstrates a connection between accretion processes occurring on very

  18. Stellar and Quasar Feedback in Concert: Effects on AGN Accretion, Obscuration, and Outflows

    CERN Document Server

    Hopkins, Philip F; Faucher-Giguere, Claude-Andre; Quataert, Eliot; Murray, Norman

    2015-01-01

    We use hydrodynamic simulations to study the interaction of realistic active galactic nucleus (AGN) feedback mechanisms (accretion-disk winds & Compton heating) with a multi-phase interstellar medium (ISM). Our ISM model includes radiative cooling and explicit stellar feedback from multiple processes. We simulate radii ~0.1-100 pc around an isolated (non-merging) black hole. These are the scales where the accretion rate onto the black hole is determined and where AGN-powered winds and radiation couple to the ISM. Our primary results include: (1) The black hole accretion rate on these scales is determined by exchange of angular momentum between gas and stars in gravitational instabilities. This produces accretion rates of ~0.03-1 Msun/yr, sufficient to power a luminous AGN. (2) The gas disk in the galactic nucleus undergoes an initial burst of star formation followed by several Myrs where stellar feedback suppresses the star formation rate per dynamical time. (3) AGN winds injected at small radii with mome...

  19. Hot Outflows in Galaxy Clusters

    CERN Document Server

    Kirkpatrick, C C

    2015-01-01

    The gas-phase metallicity distribution has been analyzed for the hot atmospheres of 29 galaxy clusters using {\\it Chandra X-ray Observatory} observations. All host brightest cluster galaxies (BCGs) with X-ray cavity systems produced by radio AGN. We find high elemental abundances projected preferentially along the cavities of 16 clusters. The metal-rich plasma was apparently lifted out of the BCGs with the rising X-ray cavities (bubbles) to altitudes between twenty and several hundred kiloparsecs. A relationship between the maximum projected altitude of the uplifted gas (the "iron radius") and jet power is found with the form $R_{\\rm Fe} \\propto P_{\\rm jet}^{0.45}$. The estimated outflow rates are typically tens of solar masses per year but exceed $100 ~\\rm M_\\odot ~yr^{-1}$ in the most powerful AGN. The outflow rates are 10% to 20% of the cooling rates, and thus alone are unable to offset a cooling inflow. Nevertheless, hot outflows effectively redistribute the cooling gas and may play a significant role at ...

  20. A Census of Intrinsic Narrow Absorption Lines in the Spectra of Quasars at z = 2-4

    Science.gov (United States)

    Misawa, Toru; Charlton, Jane C.; Eracleous, Michael; Ganguly, Rajib; Tytler, David; Kirkman, David; Suzuki, Nao; Lubin, Dan

    2007-07-01

    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, which contain 124 C IV, 12 N V, and 50 Si IV doublets, of which 18 are associated systems (within 5000 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 5000-70,000 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 data presented here were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration

  1. Quasar clustering in a galaxy and quasar formation model based on ultra high-resolution N-body simulations

    CERN Document Server

    Oogi, Taira; Ishiyama, Tomoaki; Kobayashi, Masakazu A R; Makiya, Ryu; Nagashima, Masahiro

    2015-01-01

    We investigate clustering properties of quasars using a new version of our semi-analytic model of galaxy and quasar formation with state-of-the-art cosmological N-body simulations. In this study, we assume that a major merger of galaxies triggers cold gas accretion on to a supermassive black hole and quasar activity. Our model can reproduce the downsizing trend of the evolution of quasars. We find that the median mass of quasar host dark matter haloes increases with cosmic time by an order of magnitude from z=4 (a few 1e+11 Msun) to z=1 (a few 1e+12 Msun), and depends only weakly on the quasar luminosity. Deriving the quasar bias through the quasar--galaxy cross-correlation function in the model, we find that the quasar bias does not depend on the quasar luminosity, similar to observed trends. This result reflects the fact that quasars with a fixed luminosity have various Eddington ratios and thus have various host halo masses that primarily determine the quasar bias. We also show that the quasar bias increas...

  2. Relativistic Outflows in Gamma-Ray Bursts

    CERN Document Server

    Aloy, M A

    2007-01-01

    The possibility that gamma-ray bursts (GRBs) were not isotropic emissions was devised theoretically as a way to ameliorate the huge energetic budget implied by the standard fireball model for these powerful phenomena. However, the mechanism by which after the quasy-isotropic release of a few $10^{50} $erg yields a collimated ejection of plasma could not be satisfactory explained analytically. The reason being that the collimation of an outflow by its progenitor system depends on a very complex and non-linear dynamics. That has made necessary the use of numerical simulations in order to shed some light on the viability of some likely progenitors of GRBs. In this contribution I will review the most relevant features shown by these numerical simulations and how they have been used to validate the collapsar model (for long GRBs) and the model involving the merger of compact binaries (for short GRBs).

  3. THE SUBARU HIGH-z QUASAR SURVEY: DISCOVERY OF FAINT z ∼ 6 QUASARS

    Energy Technology Data Exchange (ETDEWEB)

    Kashikawa, Nobunari; Furusawa, Hisanori; Niino, Yuu [Optical and Infrared Astronomy Division, National Astronomical Observatory, Mitaka, Tokyo 181-8588 (Japan); Ishizaki, Yoshifumi; Onoue, Masafusa; Toshikawa, Jun; Ishikawa, Shogo [Department of Astronomy, School of Science, Graduate University for Advanced Studies, Mitaka, Tokyo 181-8588 (Japan); Willott, Chris J. [Herzberg Institute of Astrophysics, National Research Council, 5071 West Saanich Road, Victoria, BC V9E 2E7 (Canada); Im, Myungshin [Center for the Exploration of the Origin of the Universe (CEOU), Astronomy Program, Department of Physics and Astronomy, Seoul National University, 1 Gwanak-rho, Gwanak-gu, Seoul 151-742 (Korea, Republic of); Shimasaku, Kazuhiro [Department of Astronomy, University of Tokyo, Hongo, Tokyo 113-0033 (Japan); Ouchi, Masami [Institute for Cosmic Ray Research, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8582 (Japan); Hibon, Pascale, E-mail: n.kashikawa@nao.ac.jp [Gemini Observatory, La Serena (Chile)

    2015-01-01

    We present the discovery of one or two extremely faint z ∼ 6 quasars in 6.5 deg{sup 2} utilizing a unique capability of the wide-field imaging of the Subaru/Suprime-Cam. The quasar selection was made in (i'-z{sub B} ) and (z{sub B} -z{sub R} ) colors, where z{sub B} and z{sub R} are bandpasses with central wavelengths of 8842 Å and 9841 Å, respectively. The color selection can effectively isolate quasars at z ∼ 6 from M/L/T dwarfs without the J-band photometry down to z{sub R} < 24.0, which is 3.5 mag deeper than the Sloan Digital Sky Survey (SDSS). We have selected 17 promising quasar candidates. The follow-up spectroscopy for seven targets identified one apparent quasar at z = 6.156 with M {sub 1450} = –23.10. We also identified one possible quasar at z = 6.041 with a faint continuum of M {sub 1450} = –22.58 and a narrow Lyα emission with HWHM =427 km s{sup –1}, which cannot be distinguished from Lyman α emitters. We derive the quasar luminosity function at z ∼ 6 by combining our faint quasar sample with the bright quasar samples by SDSS and CFHQS. Including our data points invokes a higher number density in the faintest bin of the quasar luminosity function than the previous estimate employed. This suggests a steeper faint-end slope than lower z, though it is yet uncertain based on a small number of spectroscopically identified faint quasars, and several quasar candidates still remain to be diagnosed. The steepening of the quasar luminosity function at the faint end does increase the expected emission rate of the ionizing photon; however, it only changes by a factor of approximately two to six. This was found to still be insufficient for the required photon budget of reionization at z ∼ 6.

  4. Estimating the Sunyaev - Zel'dovich signal from quasar hosts using a Halo Occupation Distribution based approach

    CERN Document Server

    Chowdhury, Dhruba Dutta

    2015-01-01

    The Sunyaev-Zeldovich (SZ) effect is a spectral distortion in the Cosmic Microwave Background (CMB), caused due to up-scattering of CMB photons by high energy electron distributions. The largest SZ distortion in the CMB is caused by the hot electrons present in the intra-cluster medium (ICM). However, several other small scale astrophysical processes can also contribute to the SZ distortion in the CMB. Analytic studies have shown that the interstellar (ISM) electron gas of the host galaxy heated by quasar feedback can also cause substantial SZ effect. For successful detection of the quasar feedback signal, the SZ signal from the virialized gas in the host halos of quasars needs to be properly quantified. In this dissertation work, I have estimated the SZ signal from quasar hosts using analytic models of the virialized gas in the ICM/ISM. As a new extension to existing work I have used the measured Halo Occupation Distribution properties of quasar hosts. The results show that the average SZ signal from quasar ...

  5. Ultrafast outflows in radio-loud active galactic nuclei

    Science.gov (United States)

    Tombesi, F.; Tazaki, F.; Mushotzky, R. F.; Ueda, Y.; Cappi, M.; Gofford, J.; Reeves, J. N.; Guainazzi, M.

    2014-09-01

    Recent X-ray observations show absorbing winds with velocities up to mildly relativistic values of the order of ˜0.1c in a limited sample of six broad-line radio galaxies. They are observed as blueshifted Fe XXV-XXVI K-shell absorption lines, similarly to the ultrafast outflows (UFOs) reported in Seyferts and quasars. In this work we extend the search for such Fe K absorption lines to a larger sample of 26 radio-loud active galactic nuclei (AGN) observed with XMM-Newton and Suzaku. The sample is drawn from the Swift Burst Alert Telescope 58-month catalogue and blazars are excluded. X-ray bright Fanaroff-Riley Class II radio galaxies constitute the majority of the sources. Combining the results of this analysis with those in the literature we find that UFOs are detected in >27 per cent of the sources. However, correcting for the number of spectra with insufficient signal-to-noise ratio, we can estimate that the incidence of UFOs is this sample of radio-loud AGN is likely in the range f ≃ (50 ± 20) per cent. A photoionization modelling of the absorption lines with XSTAR allows us to estimate the distribution of their main parameters. The observed outflow velocities are broadly distributed between vout ≲ 1000 km s-1 and vout ≃ 0.4c, with mean and median values of vout ≃ 0.133c and vout ≃ 0.117c, respectively. The material is highly ionized, with an average ionization parameter of logξ ≃ 4.5 erg s-1 cm, and the column densities are larger than NH > 1022 cm-2. Overall, these characteristics are consistent with the presence of complex accretion disc winds in a significant fraction of radio-loud AGN and demonstrate that the presence of relativistic jets does not preclude the existence of winds, in accordance with several theoretical models.

  6. The Redshift Distribution of Intervening Weak MgII Quasar Absorbers and a Curious Dependence on Quasar Luminosity

    CERN Document Server

    Evans, Jessica L; Murphy, Michael T; Nielsen, Nikole M; Klimek, Elizabeth S

    2013-01-01

    We have identified 469 MgII doublet systems having W_r >= 0.02 {\\AA} in 252 Keck/HIRES and UVES/VLT quasar spectra over the redshift range 0.1 = 1.0 {\\AA}) absorbers. For weak absorption, dN/dz toward bright quasars is ~ 25% higher than toward faint quasars (10 sigma at low redshift, 0.4 <= z <= 1.4, and 4 sigma at high redshift, 1.4 < z <= 2.34). For strong absorption the trend reverses, with dN/dz toward faint quasars being ~ 20% higher than toward bright quasars (also 10 sigma at low redshift and 4 sigma at high redshift). We explore scenarios in which beam size is proportional to quasar luminosity and varies with absorber and quasar redshifts. These do not explain dN/dz's dependence on quasar luminosity.

  7. Quasar evolution and gravitational collapse

    Energy Technology Data Exchange (ETDEWEB)

    Cavaliere, A.; Giallongo, E.; Vagnetti, F.; Messina, A.

    1983-06-01

    The paper presents three convergent results concerning the sources in theactive nuclei of quasars and radio galaxies that derive their power fromconversion of gravitational energy. We first derive, for several leading modelsbased on liberation of gravitational energy from mass in a compact supply, thelaws governing the secular change L of the primary power driving the individual sources, and identify their common and key property: L increases, and eventually decreases, linearly or faster with the power itself, so that the associated time scales t/sub s/ = L/Vertical BarLVertical Bar obey dt/sub s/, (L)/dL<0. We then describe a general statistical framework to populate with sources the (luminosity, cosmic time)-plane, based on a continuity equation that embodies a given L. We show how the main features of the populations depend primarily on L, while the memory of the initial details is easily erased. With L as derived above, we obtain basic evolutions of the density (L>0) and of the luminosity (L<0) type, with a global differential character. Finally we compute the full evolution functions, comprising a brightening (L>0) and a dimming (L<0) phase, corresponding to three such models. Sub-Eddington accretion onto a massive black hole from a star cluster that self-destroys by collisions is close to reproduce the general course of the empirical models for the optical QSO population.

  8. Red quasars not so dusty

    CERN Document Server

    Benn, C R; Carballo, R; González-Serrano, J I; Sánchez, S F

    1997-01-01

    Webster et al (1995) claimed that up to 80% of QSOs may be obscured by dust. They inferred the presence of this dust from the remarkably broad range of B-K optical-infrared colours of a sample of flat-spectrum PKS radio QSOs. If such dust is typical of QSOs, it will have rendered invisible most of those which would otherwise been have detected by optical surveys. We used the William Herschel Telescope on La Palma to obtain K infrared images of 54 B3 radio quasars selected at low frequency (mainly steep-spectrum), and we find that although several have very red optical-infrared colours, most of these can be attributed to an excess of light in K rather than a dust-induced deficit in B. We present evidence that some of the infrared excess comes from the light of stars in the host galaxy (some, as previously suggested, comes from synchrotron radiation associated with flat-spectrum radio sources). The B-K colours of the B3 QSOs provide no evidence for a large reddened population. Either the Webster et al QSOs are ...

  9. Galaxy Clustering Around Nearby Luminous Quasars

    Science.gov (United States)

    Fisher, Karl B.; Bahcall, John N.; Kirhakos, Sofia; Schneider, Donald P.

    1996-01-01

    We examine the clustering of galaxies around a sample of 20 luminous low redshift (z approx. less than 0.30) quasars observed with the Wide Field Camera-2 on the Hubble Space Telescope (HST). The HST resolution makes possible galaxy identification brighter than V = 24.5 and as close as 1 min or 2 min to the quasar. We find a significant enhancement of galaxies within a projected separation of approx. less than 100 1/h kpc of the quasars. If we model the QSO/galaxy correlation function as a power law with a slope given by the galaxy/galaxy correlation function, we find that the ratio of the QSO/galaxy to galaxy/galaxy correlation functions is 3.8 +/- 0.8. The galaxy counts within r less than 15 1/h kpc of the quasars are too high for the density profile to have an appreciable core radius (approx. greater than 100 1/h kpc). Our results reinforce the idea that low redshift quasars are located preferentially in groups of 10-20 galaxies rather than in rich clusters. We see no significant difference in the clustering amplitudes derived from radio-loud and radio-quiet subsamples.

  10. Long Term Variability of SDSS Quasars

    CERN Document Server

    De Vries, W; White, R; Becker, Bob; Vries, Wim de; White, Rick

    2003-01-01

    We use a sample of 3791 quasars from the Sloan Digital Sky Survey (SDSS) Early Data Release (EDR), and compare their photometry to historic plate material for the same set of quasars in order to study their variability properties. The time base-line we attain this way ranges from a few months to up to 50 years. In contrast to monitoring programs, where relatively few quasars are photometrically measured over shorter time periods, we utilize existing databases to extend this base-line as much as possible, at the cost of sampling per quasar. Our method, however, can easily be extended to much larger samples. We construct variability Structure Functions and compare these to the literature and model functions. From our modeling we conclude that 1) quasars are more variable toward shorter wavelengths, 2) their variability is consistent with an exponentially decaying light-curve with a typical time-scale of ~2 years, 3) these outbursts occur on typical time-scales of ~200 years. With the upcoming first data release...

  11. On the Search for Quasar Light Echoes

    CERN Document Server

    Visbal, Eli

    2007-01-01

    The UV radiation from a quasar leaves a characteristic pattern in the distribution of ionized hydrogen throughout the surrounding space. This pattern or light echo propagates through the intergalactic medium at the speed of light, and can be observed by its imprint on the Ly-alpha forest spectra of background sources. As the echo persists after the quasar has switched off, it offers the possibility of searching for dead quasars, and constraining their luminosities and lifetimes. We outline a technique to search for and characterize these light echoes. To test the method, we create artificial Ly-alpha forest spectra from cosmological simulations at z=3, apply light echoes and search for them. We show how the simulations can also be used to quantify the significance level of any detection. We find that light echoes from the brightest quasars could be found in observational data. With absorption line spectra of 100 redshift z~3-3.5 quasars or galaxies in a 1 square degree area, we expect that ~10 echoes from qua...

  12. Quasar Classification Using Color and Variability

    CERN Document Server

    Peters, Christina M; Myers, Adam D; Strauss, Michael A; Schmidt, Kasper B; Ivezić, Željko; Ross, Nicholas P; MacLeod, Chelsea L; Riegel, Ryan

    2015-01-01

    We conduct a pilot investigation to determine the optimal combination of color and variability information to identify quasars in current and future multi-epoch optical surveys. We use a Bayesian quasar selection algorithm (Richards et al. 2004) to identify 35,820 type 1 quasar candidates in a 239 square degree field of the Sloan Digital Sky Survey (SDSS) Stripe 82, using a combination of optical photometry and variability. Color analysis is performed on 5-band single- and multi-epoch SDSS optical photometry to a depth of r ~22.4. From these data, variability parameters are calculated by fitting the structure function of each object in each band with a power law model using 10 to >100 observations over timescales from ~1 day to ~8 years. Selection was based on a training sample of 13,221 spectroscopically-confirmed type-1 quasars, largely from the SDSS. Using variability alone, colors alone, and combining variability and colors we achieve 91%, 93%, and 97% quasar completeness and 98%, 98%, and 97% efficiency ...

  13. A CONSTRAINT ON QUASAR CLUSTERING AT z = 5 FROM A BINARY QUASAR

    Energy Technology Data Exchange (ETDEWEB)

    McGreer, Ian D.; Fan, Xiaohui [Steward Observatory, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Eftekharzadeh, Sarah; Myers, Adam D., E-mail: imcgreer@as.arizona.edu [Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071 (United States)

    2016-03-15

    We report the discovery of a quasar pair at z = 5 separated by 21″. Both objects were identified as quasar candidates using simple color selection techniques applied to photometric catalogs from the Canada–France–Hawaii Telescope (CFHT) Legacy Survey (CFHTLS). Spectra obtained with the MMT present no discernible offset in redshift between the two objects; on the other hand, there are clear differences in the emission line profiles and in the multiwavelength spectral energy distributions that strongly disfavor the hypothesis that they are gravitationally lensed images of a single quasar. Both quasars are surprisingly bright given their proximity (a projected separation of ∼135 kpc), with i = 19.4 and i = 21.4. Previous measurements of the luminosity function demonstrate that luminous quasars are extremely rare at z = 5; the existence of this pair suggests that quasars have strong small-scale clustering at high redshift. Assuming a real-space correlation function of the form ξ(r) ∝ (r/r{sub 0}){sup −2}, this discovery implies a correlation length of r{sub 0} ≳ 20h{sup −1} Mpc, consistent with a rapid strengthening of quasar clustering at high redshift as seen in previous observations and predicted by theoretical models where feedback effects are inefficient at shutting down black hole growth at high redshift.

  14. Blowin' in the wind: both `negative' and `positive' feedback in an obscured high-z Quasar

    CERN Document Server

    Cresci, G; Brusa, M; Marconi, A; Perna, M; Mannucci, F; Piconcelli, E; Maiolino, R; Feruglio, C; Fiore, F; Bongiorno, A; Lanzuisi, G; Merloni, A; Schramm, M; Silverman, J D; Civano, F

    2014-01-01

    Quasar feedback in the form of powerful outflows is invoked as a key mechanism to quench star formation in galaxies, preventing massive galaxies to over-grow and producing the red colors of ellipticals. On the other hand, some models are also requiring `positive' AGN feedback, inducing star formation in the host galaxy through enhanced gas pressure in the interstellar medium. However, finding observational evidence of the effects of both types of feedback is still one of the main challenges of extragalactic astronomy, as few observations of energetic and extended radiatively-driven winds are available. Here we present SINFONI near infrared integral field spectroscopy of XID2028, an obscured, radio-quiet z=1.59 QSO detected in the XMM-COSMOS survey, in which we clearly resolve a fast (1500 km/s) and extended (up to 13 kpc from the black hole) outflow in the [OIII] lines emitting gas, whose large velocity and outflow rate are not sustainable by star formation only. The narrow component of Ha emission and the re...

  15. A large sample of binary quasars: Does quasar bias tracks from Mpc scale to kpc scales?

    Science.gov (United States)

    Eftekharzadeh, Sarah; Myers, Adam D.; Djorgovski, Stanislav G.; Graham, Matthew J.

    2017-01-01

    We present the most precise estimate to date of the bias of quasars on very small scales, based on a measurement of the clustering of 47 spectroscopically confirmed binary quasars with proper transverse separations of ~25 h^{-1} kpc. The quasars in our sample, which is an order-of-magnitude larger than previous samples, are targeted using a Kernel Density Estimation technique (KDE) applied to Sloan Digital Sky Survey (SDSS) imaging over most of the SDSS area. Our sample is "complete," in that all possible pairs of binary quasars across our area of interest have been spectroscopically confirmed from a combination of previous surveys and our own long-slit observational campaign. We determine the projected correlation function of quasars (\\bar W_p) in four bins of proper transverse scale over the range 17.0 \\lesssim R_{prop} \\lesssim 36.2 h^{-1} kpc. Due to our large sample size, our measured projected correlation function in each of these four bins of scale is more than twice as precise as any previous measurement made over our {\\em full} range of scales. We also measure the bias of our quasar sample in four slices of redshift across the range 0.43 \\le z \\le 2.26 and compare our results to similar measurements of how quasar bias evolves on Mpc-scales. This measurement addresses the question of whether it is reasonable to assume that quasar bias evolves with redshift in a similar fashion on both Mpc and kpc scales. Our results can meaningfully constrain the one-halo term of the Halo Occupation Distribution (HOD) of quasars and how it evolves with redshift. This work was partially supported by NSF grant 1515404.

  16. Unveiling hidden black holes in the cosmic web: Dark matter halos of WISE quasars from Planck CMB lensing

    Science.gov (United States)

    Hickox, Ryan

    The WISE and Planck surveys have now produced groundbreaking data sets which, in concert, can be exploited to obtain revolutionary constraints on the evolution of structure in the Universe. One particularly powerful application of WISE has been to uncover millions of the previously "hidden" obscured quasars, rapidly growing supermassive black holes that are shrouded in gas and dust and so are not detectable using traditional ground-based optical and near-IR techniques. Recently, Planck has produced the most precise all-sky map to date of dark matter structures via the lensing of the cosmic microwave background (CMB). We propose to combine these data sets to obtain a uniquely powerful measurement of the link between rapidly growing black holes and their host dark matter structures, by cross-correlating the density field of WISE-selected quasars with the CMB lensing convergence maps obtained from Planck. This proposal will build on our current ADAP program (NNX12AE38G), which studies the host dark matter halos of WISE-selected quasars via spatial clustering. NNX12AE38G involves a detailed characterization of the redshifts, luminosities, and spectral energy distributions of WISE-selected quasars and uses new techniques to measure how quasars cluster around themselves. NNX12AE38G has contributed to more than 10 journal articles and 5 conference proceedings. Building on our current work, an even more complete understanding of the link between black holes and their host dark matter structures is possible if we employ an independent method for measuring the clustering bias (and thus characteristic halo mass) of the quasar population. This has recently become possible using CMB lensing maps. In the past two years, our team has conducted an initial analysis covering 2500 square degrees using WISE-selected quasars and lensing maps from the South Pole Telescope (Geach, Hickox, Myers et al., 2013), and have implemented this technique with Planck over part of the SDSS region

  17. BeppoSAX observations of quasars

    Energy Technology Data Exchange (ETDEWEB)

    Fiore, F.; Mineo, T.; Laor, A.; Giallongo, E

    1999-01-01

    We present results from recent BeppoSAX observations of low redshift (z<0.4, PG sample) and high redshift (2quasars. Significant curvature has been detected in the spectra of the observed PGs: the spectrum flattens by 0.5 above 2 keV. The possible presence of narrow features in the MECS spectra is discussed. Intrinsic absorption has been measured in the z=3.9 radio-loud quasar 1745+624. The z=2.3 radio-quiet quasar HE1104-1805 has been found at a very low flux level, in comparison with previous ROSAT and ASCA observations, implying large (factor of {approx} 4) variability on years timescales.

  18. Detecting the First Quasars with ALMA

    Science.gov (United States)

    Schleicher, Dominik R. G.; Spaans, Marco; Klessen, Ralf S.

    2010-05-01

    We show that ALMA is the first telescope that can probe the dust-obscured central region of quasars at z > 5 with a maximum resolution of ~ 30 pc employing the 18 km baseline. We explore the possibility of detecting the first quasars with ALMA (Schleicher, Spaans, & Klessen 2009). For this purpose, we adopt the Seyfert 2 galaxy NGC 1068 as a reference system and calculate the expected fluxes if this galaxy were placed at high redshift. This choice is motivated by the detailed observations available for this system and the absence of any indication for an evolution in metallicity in high-redshift quasars. It is a conservative choice due to the moderate column densities in NGC 1068, leading to moderate fluxes.

  19. The Sudden Death of the Nearest Quasar

    CERN Document Server

    Schawinski, Kevin; Virani, Shanil; Urry, C Megan; Keel, William C; Natarajan, Priyamvada; Lintott, Chris J; Manning, Anna; Coppi, Paolo; Kaviraj, Sugata; Bamford, Steven P; Jozsa, Gyula I G; Garrett, Michael; van Arkel, Hanny; Gay, Pamela; Fortson, Lucy; 10.1088/2041-8205/724/1/L30

    2010-01-01

    Galaxy formation is significantly modulated by energy output from supermassive black holes at the centers of galaxies which grow in highly efficient luminous quasar phases. The timescale on which black holes transition into and out of such phases is, however, unknown. We present the first measurement of the shutdown timescale for an individual quasar using X-ray observations of the nearby galaxy IC 2497, which hosted a luminous quasar no more than 70,000 years ago that is still seen as a light echo in `Hanny's Voorwerp', but whose present-day radiative output is lower by at least 2 and more likely by over 4 orders of magnitude. This extremely rapid shutdown provides new insights into the physics of accretion in supermassive black holes, and may signal a transition of the accretion disk to a radiatively inefficient state.

  20. Data Mining for Gravitationally Lensed Quasars

    CERN Document Server

    Agnello, Adriano; Treu, Tommaso; Marshall, Philip J

    2014-01-01

    Gravitationally lensed (GL) quasars are brighter than their unlensed counterparts and produce images with distinctive morphological signatures. Past searches and target selection algorithms, in particular the Sloan Quasar Lens Search (SQLS), have relied on basic morphological criteria, which were applied to samples of bright, spectroscopically confirmed quasars. The SQLS techniques are not sufficient for searching into new surveys (e.g. DES, PS1, LSST), because spectroscopic information is not readily available and the large data volume requires higher purity in target/candidate selection. We carry out a systematic exploration of machine learning techniques and demonstrate that a two step strategy can be highly effective. In the first step we use catalog-level information ($griz$+WISE magnitudes, second moments) to preselect targets, using artificial neural networks. The accepted targets are then inspected with pixel-by-pixel pattern recognition algorithms (Gradient-Boosted Trees), to form a final set of cand...

  1. The Extreme Ultraviolet Variability of Quasars

    Science.gov (United States)

    Punsly, Brian; Marziani, Paola; Zhang, Shaohua; Muzahid, Sowgat; O’Dea, Christopher P.

    2016-10-01

    We study the extreme ultraviolet (EUV) variability (rest frame wavelengths 500–920 Å) of high-luminosity quasars using Hubble Space Telescope (HST) (low to intermediate redshift sample) and Sloan Digital sky Survey (SDSS) (high redshift sample) archives. The combined HST and SDSS data indicates a much more pronounced variability when the sampling time between observations in the quasar rest frame is \\gt 2× {10}7 {{s}} compared to \\lt 1.5× {10}7 s. Based on an excess variance analysis, for time intervals \\lt 2× {10}7 {{s}} in the quasar rest frame, 10% of the quasars (4/40) show evidence of EUV variability. Similarly, for time intervals \\gt 2× {10}7 {{s}} in the quasar rest frame, 55% of the quasars (21/38) show evidence of EUV variability. The propensity for variability does not show any statistically significant change between 2.5× {10}7 {{s}} and 3.16× {10}7 {{s}} (1 year). The temporal behavior is one of a threshold time interval for significant variability as opposed to a gradual increase on these timescales. A threshold timescale can indicate a characteristic spatial dimension of the EUV region. We explore this concept in the context of the slim disk models of accretion. We find that for rapidly spinning black holes, the radial infall time to the plunge region of the optically thin surface layer of the slim disk that is responsible for the preponderance of the EUV flux emission (primarily within 0–7 black hole radii from the inner edge of the disk) is consistent with the empirically determined variability timescale.

  2. Quasar polarization with ultralight (pseudo-)scalars

    Indian Academy of Sciences (India)

    Ki-Young choi; Subhayan Mandal; Chang Sub Shin

    2016-01-01

    Recently, it was shown that the absence of circular polarization of visible light from quasars severely constrains the interpretation of axion-like particles (ALPs) as a solution for the generation of linear polarization. Furthermore, the new observation of linear polarization in radio wavelength from quasars, similar to the earlier observation performed in the optical bands, makes the ALPs scenario inconsistent with at least one of the two observations. In this study, we extend this scenario by including more scalars. We find that the effects from scalar and pseudoscalar neutralize each other, thereby suppressing the circular polarization, while preserving consistent linear polarization, as observed in both the visible and radio wave bands.

  3. Unconventional aqueous humor outflow: A review.

    Science.gov (United States)

    Johnson, Mark; McLaren, Jay W; Overby, Darryl R

    2017-05-01

    Aqueous humor flows out of the eye primarily through the conventional outflow pathway that includes the trabecular meshwork and Schlemm's canal. However, a fraction of aqueous humor passes through an alternative or 'unconventional' route that includes the ciliary muscle, supraciliary and suprachoroidal spaces. From there, unconventional outflow may drain through two pathways: a uveoscleral pathway where aqueous drains across the sclera to be resorbed by orbital vessels, and a uveovortex pathway where aqueous humor enters the choroid to drain through the vortex veins. We review the anatomy, physiology and pharmacology of these pathways. We also discuss methods to determine unconventional outflow rate, including direct techniques that use radioactive or fluorescent tracers recovered from tissues in the unconventional pathway and indirect methods that estimate unconventional outflow based on total outflow over a range of pressures. Indirect methods are subject to a number of assumptions and generally give poor agreement with tracer measurements. We review the variety of animal models that have been used to study conventional and unconventional outflow. The mouse appears to be a promising model because it captures several aspects of conventional and unconventional outflow dynamics common to humans, although questions remain regarding the magnitude of unconventional outflow in mice. Finally, we review future directions. There is a clear need to develop improved methods for measuring unconventional outflow in both animals and humans. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. The COMPLETE Survey of Outflows in Perseus

    CERN Document Server

    Arce, Hector G; Goodman, Alyssa A; Pineda, Jaime E; Halle, Michael W; 10.1088/0004-637X/715/2/1170

    2010-01-01

    We present a study on the impact of molecular outflows in the Perseus molecular cloud complex using the COMPLETE survey large-scale 12CO(1-0) and 13CO(1-0) maps. We used three-dimensional isosurface models generated in RA-DEC-Velocity space to visualize the maps. This rendering of the molecular line data allowed for a rapid and efficient way to search for molecular outflows over a large (~ 16 sq. deg.) area. Our outflow-searching technique detected previously known molecular outflows as well as new candidate outflows. Most of these new outflow-related high-velocity features lie in regions that have been poorly studied before. These new outflow candidates more than double the amount of outflow mass, momentum, and kinetic energy in the Perseus cloud complex. Our results indicate that outflows have significant impact on the environment immediately surrounding localized regions of active star formation, but lack the energy needed to feed the observed turbulence in the entire Perseus complex. This implies that oth...

  5. SWAS Observations of Water in Molecular Outflows

    CERN Document Server

    Franklin, J; Kaufman, M J; Melnick, G J; Neufeld, D A; Hollenbach, D J; Bergin, E A

    2007-01-01

    We present SWAS detections of the ground-state 1(10)-1(01) transition of o-H2O at 557 GHz in 18 molecular outflows. These results are combined with ground-based observations of the J=1-0 transitions of 12CO and 13CO obtained at the FCRAO and, for a subset of the outflows, data from ISO. Assuming the SWAS water line emission originates from the same gas traced by CO emission, we find that the outflowing gas in most outflows has an o-H2O abundance relative to H2 of between 10(-7) and 10(-6). Analysis of the water abundance as a function of outflow velocity reveals a strong dependence. The water abundance increases with velocity, and at the highest outflow velocities some outflows have relative o-H2O abundances of order 10(-4). However the mass of gas with such elevated water abundances represents less that 1% of the total outflow gas mass. The ISO LWS observations of high-J rotational lines of CO and the 179.5 micron transition of o-H2O provide evidence for a warmer outflow component than required to produce ei...

  6. Morphologies of protostellar outflows: An ALMA view

    CERN Document Server

    Peters, Thomas; Seifried, Daniel; Banerjee, Robi; Klessen, Ralf S

    2014-01-01

    The formation of stars is usually accompanied by the launching of protostellar outflows. Observations with the Atacama Large Millimetre/sub-millimetre Array (ALMA) will soon revolutionalise our understanding of the morphologies and kinematics of these objects. In this paper, we present synthetic ALMA observations of protostellar outflows based on numerical magnetohydrodynamic collapse simulations. We find significant velocity gradients in our outflow models and a very prominent helical structure within the outflows. We speculate that the disk wind found in the ALMA Science Verification Data of HD 163296 presents a first instance of such an observation.

  7. Using quasars as standard clocks for measuring cosmological redshift.

    Science.gov (United States)

    Dai, De-Chang; Starkman, Glenn D; Stojkovic, Branislav; Stojkovic, Dejan; Weltman, Amanda

    2012-06-08

    We report hitherto unnoticed patterns in quasar light curves. We characterize segments of the quasar's light curves with the slopes of the straight lines fit through them. These slopes appear to be directly related to the quasars' redshifts. Alternatively, using only global shifts in time and flux, we are able to find significant overlaps between the light curves of different pairs of quasars by fitting the ratio of their redshifts. We are then able to reliably determine the redshift of one quasar from another. This implies that one can use quasars as standard clocks, as we explicitly demonstrate by constructing two independent methods of finding the redshift of a quasar from its light curve.

  8. Helium Reionization Simulations. I. Modeling Quasars as Radiation Sources

    CERN Document Server

    La Plante, Paul

    2015-01-01

    We introduce a new project to understand helium reionization using fully coupled $N$-body, hydrodynamics, and radiative transfer simulations. This project aims to capture correctly the thermal history of the intergalactic medium (IGM) as a result of reionization and make predictions about the Lyman-$\\alpha$ forest and baryon temperature-density relation. The dominant sources of radiation for this transition are quasars, so modeling the source population accurately is very important for making reliable predictions. In this first paper, we present a new method for populating dark matter halos with quasars. Our set of quasar models include two different light curves, a lightbulb (simple on/off) and symmetric exponential model, and luminosity-dependent quasar lifetimes. Our method self-consistently reproduces an input quasar luminosity function (QLF) given a halo catalog from an $N$-body simulation, and propagates quasars through the merger history of halo hosts. After calibrating quasar clustering using measurem...

  9. Wind from black hole accretion disk as the driver of a molecular outflow in a galaxy

    CERN Document Server

    Tombesi, F; Veilleux, S; Reeves, J N; Gonzalez-Alfonso, E; Reynolds, C S

    2015-01-01

    Powerful winds driven by active galactic nuclei (AGN) are often invoked to play a fundamental role in the evolution of both supermassive black holes (SMBHs) and their host galaxies, quenching star formation and explaining the tight SMBH-galaxy relations. Recent observations of large-scale molecular outflows in ultra-luminous infrared galaxies (ULIRGs) have provided the evidence to support these studies, as they directly trace the gas out of which stars form. Theoretical models suggest an origin of these outflows as energy-conserving flows driven by fast AGN accretion disk winds. Previous claims of a connection between large-scale molecular outflows and AGN activity in ULIRGs were incomplete because they were lacking the detection of the putative inner wind. Conversely, studies of powerful AGN accretion disk winds to date have focused only on X-ray observations of local Seyferts and a few higher redshift quasars. Here we show the clear detection of a powerful AGN accretion disk wind with a mildly relativistic ...

  10. Quasars at z=6: the survival of the fittest

    CERN Document Server

    Volonteri, M

    2006-01-01

    The Sloan Digital Sky survey detected luminous quasars at very high redshift, z>6. Follow-up observations indicated that at least some of these quasars are powered by supermassive black holes (SMBHs) with masses in excess of billion solar masses. SMBHs, therefore, seem to have already existed when the Universe was less than 1 Gyr old, and the bulk of galaxy formation still has to take place. We investigate in this paper to which extent accretion and dynamical processes influence the early growth of SMBHs. We assess the impact of (i) black hole mergers, (ii) the influence of the merging efficiency and (iii) the negative contribution due to dynamical effects which can kick black holes out of their host halos (gravitational recoil). We find that if accretion is always limited by the Eddington rate via a thin disc, the maximum radiative efficiency allowed to reproduce the LF at z=6 is of order 12%, when the adverse effect of the gravitational recoil is taken into consideration. Dynamical effects cannot be neglect...

  11. STRUCTURE FUNCTION ANALYSIS OF LONG-TERM QUASAR VARIABILITY

    Energy Technology Data Exchange (ETDEWEB)

    de Vries, W; Becker, R; White, R; Loomis, C

    2004-11-15

    In our second paper on long-term quasar variability, we employ a much larger database of quasars than in de Vries, Becker & White. This expanded sample, containing 35,165 quasars from the Sloan Digital Sky Survey Data Release 2, and 6,413 additional quasars in the same area of the sky taken from the 2dF QSO Redshift Survey, allows us to significantly improve on our earlier conclusions. As before, all the historic quasar photometry has been calibrated onto the SDSS scale by using large numbers of calibration stars around each quasar position. We find the following: (1) the outbursts have an asymmetric light-curve profile, with a fast-rise, slow-decline shape; this argues against a scenario in which micro-lensing events along the line-of-sight to the quasars are dominating the long-term variations in quasars; (2) there is no turnover in the Structure Function of the quasars up to time-scales of {approx}40 years, and the increase in variability with increasing time-lags is monotonic and constant; and consequently, (3) there is not a single preferred characteristic outburst time-scale for the quasars, but most likely a continuum of outburst time-scales, (4) the magnitude of the quasar variability is a function of wavelength: variability increases toward the blue part of the spectrum, (5) high-luminosity quasars vary less than low-luminosity quasars, consistent with a scenario in which variations have limited absolute magnitude. Based on this, we conclude that quasar variability is intrinsic to the Active Galactic Nucleus, is caused by chromatic outbursts/flares with a limited luminosity range and varying time-scales, and which have an overall asymmetric light-curve shape. Currently the model that has the most promise of fitting the observations is based on accretion disk instabilities.

  12. New quasar surveys with WIRO: Searching for high redshift (z~6) quasar candidates

    Science.gov (United States)

    Haze Nunez, Evan; Bassett, Neil; Deam, Sophie; Dixon, Don; Griffith, Emily; Harvey, William Bradford; Lee, Daniel; Lyke, Bradley; Parziale, Ryan; Witherspoon, Catherine; Myers, Adam D.; Findlay, Joseph; Kobulnicky, Henry A.; Dale, Daniel A.

    2017-01-01

    High redshift quasars (z~6) are of great interest to fundamental astronomy due to the information they hold about the early universe. With their low number density in the sky, however, they are elusive objects. Reported here is our search for these high redshift quasars using the Wyoming Infrared Observatory (WIRO) 2.3m telescope. We search for potential candidates that have been detected by surveys such as WISE, which have been mostly redshifted out of the optical. The main emission feature of these quasars (the Lyman-Alpha line at ~1216 Angstroms rest-frame) would be redshifted to the z-band or beyond. This means that the quasars should have very low levels of i-band flux. These objects are known as i-dropouts. By imaging the quasars in the i-band and running photometric analysis on our fields, candidates can be identified or rejected by whether or not they appear in our fields. We also provide an analysis of the colors of our candidate high-redshift quasars.This work is supported by the National Science Foundation under REU grant AST1560461

  13. THE LARGE SKY AREA MULTI-OBJECT FIBER SPECTROSCOPIC TELESCOPE QUASAR SURVEY: QUASAR PROPERTIES FROM THE FIRST DATA RELEASE

    Energy Technology Data Exchange (ETDEWEB)

    Ai, Y. L.; Wu, Xue-Bing; Yang, Jinyi; Yang, Qian; Wang, Feige; Guo, Rui; Dong, Xiaoyi [Department of Astronomy, School of Physics, Peking University, Beijing 100871 (China); Zuo, Wenwen; Shen, S.-Y. [Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030 (China); Zhang, Y.-X.; Yuan, H.-L.; Song, Y.-H.; Yang, M.; Wu, H.; Shi, J.-R.; He, B.-L.; Lei, Y.-J.; Li, Y.-B. [Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences 100012, Beijing (China); Wang, Jianguo; Dong, Xiaobo, E-mail: aiyl@pku.edu.cn [Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011 (China); and others

    2016-02-15

    We present preliminary results of the quasar survey in the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) first data release (DR1), which includes the pilot survey and the first year of the regular survey. There are 3921 quasars reliably identified, among which 1180 are new quasars discovered in the survey. These quasars are at low to median redshifts, with a highest z of 4.83. We compile emission line measurements around the Hα, Hβ, Mg ii, and C iv regions for the new quasars. The continuum luminosities are inferred from SDSS photometric data with model fitting, as the spectra in DR1 are non-flux-calibrated. We also compile the virial black hole mass estimates, with flags indicating the selection methods, and broad absorption line quasars. The catalog and spectra for these quasars are also available. Of the 3921 quasars, 28% are independently selected with optical–infrared colors, indicating that the method is quite promising for the completeness of the quasar survey. LAMOST DR1 and the ongoing quasar survey will provide valuable data for studies of quasars.

  14. Giant scattering cones in obscured quasars

    CERN Document Server

    Obied, Georges; Wylezalek, Dominika; Liu, Guilin

    2015-01-01

    We analyze Hubble Space Telescope observations of scattering regions in 20 luminous obscured quasars at $0.24quasar hosts' star formation rates. Modeling these regions as illuminated dusty cones, we estimate the radial density distributions of the interstellar medium as well as the geometric properties of circumnuclear quasar obscuration -- inclinations and covering factors. Small derived opening angles (median half-angle and standard deviation 27\\dg$\\pm$9\\dg) are inconsistent with a 1:1 type 1 / type 2 ratio. We suggest that quasar obscuration is patchy and that the observer has a $\\sim 40\\%$ chan...

  15. The Extreme Ultraviolet Variability of Quasars

    CERN Document Server

    Punsly, Brian; Zhang, Shaohua; Muzahid, Sowgat; O'Dea, Christopher P

    2016-01-01

    We study the extreme ultraviolet (EUV) variability (rest frame wavelengths 500 - 920 $\\AA$) of high luminosity quasars using HST (low to intermediate redshift sample) and SDSS (high redshift sample) archives. The combined HST and SDSS data indicates a much more pronounced variability when the sampling time between observations in the quasar rest frame is $> 2\\times 10^{7}$ sec compared to $2\\times 10^{7}$ sec in the quasar rest frame, $55\\%$ of the quasars (21/38) show evidence of EUV variability. The propensity for variability does not show any statistically significant change between $2.5\\times 10^{7}$ sec and $3.16\\times 10^{7}$ sec (1 yr). The temporal behavior is one of a threshold time interval for significant variability as opposed to a gradual increase on these time scales. A threshold time scale can indicate a characteristic spatial dimension of the EUV region. We explore this concept in the context of the slim disk models of accretion. We find that for rapidly spinning black holes, the radial infall...

  16. Theoretical spectroscopy of quasars within Karlsson's law

    CERN Document Server

    Moret-Bailly, Jacques

    2016-01-01

    The law introduced by Karlsson in spectroscopy of low-redshift quasars involves the Lyman spectrum of hydrogen atoms. Thus, it appears necessary to study the concepts introduced by a standard spectroscopy of quasars, studied here, with those deducted from $\\Lambda$-CDM.A visible absorption of a sharp and saturated spectral line in a gas requires a long path without perturbations as collisions or cosmological redshift. Spectra of absorbed, saturated lines of quasars obeying Karlsson's law mainly result from interactions of natural, thermal light radiated by quasar with relatively cold, low presure atomic hydrogen. These lines are produced by three processes: a) A conventional absorption in a relatively cold gas produces a set of lines; b) These lines are multiplied by absorption after fundamental 3K or 4K redshifts, where K is Karlsson's constant: Spectra show that redshifts 3K (or 4K) exactly bring absorbed Lyman beta (or gamma) line on Lyman alpha: redshift almost disappears, and gas lines are intensely abso...

  17. Black-hole masses of distant quasars

    DEFF Research Database (Denmark)

    Vestergaard, Marianne

    2011-01-01

    A brief overview of the methods commonly used to determine or estimate the black hole mass in quiescent or active galaxies is presented and it is argued that the use of mass-scaling relations is both a reliable and the preferred method to apply to large samples of distant quasars. The method uses...

  18. Measuring Distances to Remote Galaxies and Quasars.

    Science.gov (United States)

    McCarthy, Patrick J.

    1988-01-01

    Describes the use of spectroscopy and the redshift to measure how far an object is by measuring how fast it is receding from earth. Lists the most distant quasars yet found. Tables include "Redshift vs. Distance" and "Distances to Celestial Objects for Various Cosmologies." (CW)

  19. Quasar Astrophysics with the Space Interferometry Mission

    Science.gov (United States)

    Unwin, Stephen; Wehrle, Ann; Meier, David; Jones, Dayton; Piner, Glenn

    2007-01-01

    Optical astrometry of quasars and active galaxies can provide key information on the spatial distribution and variability of emission in compact nuclei. The Space Interferometry Mission (SIM PlanetQuest) will have the sensitivity to measure a significant number of quasar positions at the microarcsecond level. SIM will be very sensitive to astrometric shifts for objects as faint as V = 19. A variety of AGN phenomena are expected to be visible to SIM on these scales, including time and spectral dependence in position offsets between accretion disk and jet emission. These represent unique data on the spatial distribution and time dependence of quasar emission. It will also probe the use of quasar nuclei as fundamental astrometric references. Comparisons between the time-dependent optical photocenter position and VLBI radio images will provide further insight into the jet emission mechanism. Observations will be tailored to each specific target and science question. SIM will be able to distinguish spatially between jet and accretion disk emission; and it can observe the cores of galaxies potentially harboring binary supermassive black holes resulting from mergers.

  20. Quasar Mass Functions Across Cosmic Time

    DEFF Research Database (Denmark)

    Vestergaard, Marianne

    2010-01-01

    I present mass functions of actively accreting black holes detected in different quasar surveys which in concert cover a wide range of cosmic history. I briefly address what we learn from these mass functions. I summarize the motivation for such a study and the methods by which we determine black...

  1. Quasar Elemental Abundances at High Redshifts

    DEFF Research Database (Denmark)

    Dietrich, M.; Hamann, F.; Shields, J. C.

    2003-01-01

    We examine rest-frame ultraviolet spectra of 70 high redshift quasars (z>3.5) to study the chemical enrichment history of the gas closely related to the quasars, and thereby estimate the epoch of first star formation. The fluxes of several ultraviolet emission lines were investigated within...... the framework of the most recent photoionization models to estimate the metallicity of the gas associated with the high-z quasars. Standard photoionization parameters and the assumption of secondary nitrogen enrichment indicate an average abundance of Z/Z_sol = 4 to 5 in the line emitting gas. Assuming a time...... scale of t_evol = 0.5 - 0.8 Gyrs for the chemical enrichment of the gas, the first major star formation for quasars with z>=4 should have started at a redshift of z_f = 6 - 8, corresponding to an age of the universe of several 10^8 yrs (H_o = 65 km/s/Mpc, Omega_M = 0.3, Omega_Lambda = 0.7). We note...

  2. Quasar absorption lines and the intergalactic medium

    CERN Document Server

    Jannuzi, B T

    1996-01-01

    The importance of HST for the study of quasar absorption lines and of the nature of the intergalactic medium is illustrated by reviewing selected results from past HST observations. Topics reviewed include the study of Ly-alpha absorbers at low redshift and the search for a diffuse IGM at high redshifts.

  3. Quasar Elemental Abundances at High Redshifts

    CERN Document Server

    Dietrich, M; Shields, J C; Constantin, A; Heidt, J; Jäger, K; Vestergaard, M; Wagner, S J

    2003-01-01

    We examine rest-frame ultraviolet spectra of 70 high redshift quasars (z>3.5) to study the chemical enrichment history of the gas closely related to the quasars, and thereby estimate the epoch of first star formation. The fluxes of several ultraviolet emission lines were investigated within the framework of the most recent photoionization models to estimate the metallicity of the gas associated with the high-z quasars. Standard photoionization parameters and the assumption of secondary nitrogen enrichment indicate an average abundance of Z/Z_sol = 4 to 5 in the line emitting gas. Assuming a time scale of t_evol = 0.5 - 0.8 Gyrs for the chemical enrichment of the gas, the first major star formation for quasars with z>=4 should have started at a redshift of z_f = 6 - 8, corresponding to an age of the universe of several 10^8 yrs (H_o = 65 km/s/Mpc, Omega_M = 0.3, Omega_Lambda = 0.7). We note that this also appears to be the era of re-ionization of the universe. Finally, there is some evidence for a positive lum...

  4. Magnetic Fields in Quasar Cores, 2

    CERN Document Server

    Taylor, G B

    1999-01-01

    Multi-frequency polarimetry with the Very Long Baseline Array (VLBA) telescope has revealed absolute Faraday Rotation Measures (RMs) in excess of 1000 rad/m/m in the central regions of 7 out of 8 strong quasars studied (e.g., 3C 273, 3C 279, 3C 395). Beyond a projected distance of ~20 pc, however, the jets are found to have |RM| < 100 rad/m/m. Such sharp RM gradients cannot be produced by cluster or galactic-scale magnetic fields, but rather must be the result of magnetic fields organized over the central 1-100 pc. The RMs of the sources studied to date and the polarization properties of BL Lacs, quasars and galaxies are shown to be consistent so far with the predictions of unified schemes. The direct detection of high RMs in these quasar cores can explain the low fractional core polarizations usually observed in quasars at centimeter wavelengths as the result of irregularities in the Faraday screen on scales smaller than the telescope beam. Variability in the RM of the core is reported for 3C 279 between ...

  5. Quasar Astrophysics with the Space Interferometry Mission

    Science.gov (United States)

    Unwin, Stephen; Wehrle, Ann; Meier, David; Jones, Dayton; Piner, Glenn

    2007-01-01

    Optical astrometry of quasars and active galaxies can provide key information on the spatial distribution and variability of emission in compact nuclei. The Space Interferometry Mission (SIM PlanetQuest) will have the sensitivity to measure a significant number of quasar positions at the microarcsecond level. SIM will be very sensitive to astrometric shifts for objects as faint as V = 19. A variety of AGN phenomena are expected to be visible to SIM on these scales, including time and spectral dependence in position offsets between accretion disk and jet emission. These represent unique data on the spatial distribution and time dependence of quasar emission. It will also probe the use of quasar nuclei as fundamental astrometric references. Comparisons between the time-dependent optical photocenter position and VLBI radio images will provide further insight into the jet emission mechanism. Observations will be tailored to each specific target and science question. SIM will be able to distinguish spatially between jet and accretion disk emission; and it can observe the cores of galaxies potentially harboring binary supermassive black holes resulting from mergers.

  6. Effects of Quasar Feedback in Galaxy Groups

    CERN Document Server

    Bhattacharya, Suman; Kosowsky, Arthur

    2007-01-01

    We study the effect of quasar feedback on distributions of baryons in galaxy groups using high-resolution numerical simulations. We use the entropy-conserving Gadget code that includes gas cooling and star formation, modified to include a physically-based model of quasar feedback. For a sample of ten galaxy group-sized dark matter halos with masses in the range of 1 to $5\\times 10^{13} M_{\\odot}/h$, star formation is suppressed by more than 30% in the inner regions due to the additional pressure support by quasar feedback, while gas is driven from the inner region towards the outer region of the halos. As a result, the average gas density is 20% lower in the inner region and 10% higher in the outer region in the simulation, compared to a similar simulation with no quasar feedback. Gas pressure is also higher in the outer region, while temperature and entropy are enhanced in the inner region. The total group gas fraction in the two simulations generally differs by less than 10%. We also find a small enhancemen...

  7. Galaxy clustering around nearby luminous quasars

    CERN Document Server

    Fisher, K B; Kirhakos, S; Schneider, D P; Fisher, Karl B; Bahcall, John N; Schneider, Donald P

    1996-01-01

    We examine the clustering of galaxies around a sample of 20 luminous low redshift (z 100 kpc). Our results reinforce the idea that low redshift quasars are located preferentially in groups of 10-20 galaxies rather than in rich clusters. We see no significant difference in the clustering amplitudes derived from radio-loud and radio-quiet subsamples.

  8. Outflow - Core Interaction in Barnard 1

    CERN Document Server

    Hiramatsu, Masaaki; Takakuwa, Shigehisa

    2010-01-01

    In order to study how outflows from protostars influence the physical and chemical conditions of the parent molecular cloud, we have observed Barnard 1 (B1) main core, which harbors four Class 0 and three Class I sources, in the CO (J=1-0), CH3OH (J_K=2_K-1_K), and the SiO (J=1-0) lines using the NRO 45 m telescope. We have identified three CO outflows in this region; one is an elongated (~ 0.3 pc) bipolar outflow from a Class 0 protostar B1-c in the submillimeter clump SMM 2, another is a rather compact (~ 0.1 pc) outflow from a Class I protostar B1 IRS in the clump SMM 6, and the other is extended outflow from a Class I protostar in SMM 11. In the western lobe of the SMM 2 outflow, both the SiO and CH3OH lines show broad redshifted wings with the terminal velocities of 25 km/s and 13 km/s, respectively. It is likely that the shocks caused by the interaction between the outflow and ambient gas enhance the abundance of SiO and CH3OH in the gas phase. The total energy input rate by the outflows (1.1x10^{-3} Ls...

  9. A cosmic double helix in the archetypical quasar 3C273.

    Science.gov (United States)

    Lobanov, A P; Zensus, J A

    2001-10-05

    Finding direct evidence for plasma instability in extragalactic jets is crucial for understanding the nature of relativistic outflows from active galactic nuclei. Our radio interferometric observations of the quasar 3C273 made with the orbiting radio telescope, HALCA, and an array of ground telescopes have yielded an image in which the emission across the jet is resolved, revealing two threadlike patterns that form a double helix inside the jet. This double helical structure is consistent with a Kelvin-Helmholtz instability, and at least five different instability modes can be identified and modeled by a light jet with a Lorentz factor of 2 and Mach number of 3.5. The model reproduces in detail the internal structure of the jet on scales of up to 30 milli-arc seconds ( approximately 300 parsecs) and is consistent with the general morphology of the jet on scales of up to 1 kiloparsec.

  10. Mass Functions of the Active Black Holes in Distant Quasars from the Large Bright Quasar Survey, the Bright Quasar Survey, and the Color-Selected Sample of the SDSS Fall Equatorial Stripe

    DEFF Research Database (Denmark)

    Vestergaard, Marianne; Osmer, Patrick S.

    2009-01-01

    We present mass functions of distant actively accreting supermassive black holes residing in luminous quasars discovered in the Large Bright Quasar Survey, the Bright Quasar Survey, and the Fall Equatorial Stripe of the Sloan Digital Sky Survey (SDSS). The quasars cover a wide range of redshifts (0...

  11. Spatially Resolved Patchy Lyα Emission within the Central Kiloparsec of a Strongly Lensed Quasar Host Galaxy at z = 2.8

    Science.gov (United States)

    Bayliss, Matthew B.; Sharon, Keren; Acharyya, Ayan; Gladders, Michael D.; Rigby, Jane R.; Bian, Fuyan; Bordoloi, Rongmon; Runnoe, Jessie; Dahle, Hakon; Kewley, Lisa; Florian, Michael; Johnson, Traci; Paterno-Mahler, Rachel

    2017-08-01

    We report the detection of extended Lyα emission from the host galaxy of SDSS J2222+2745, a strongly lensed quasar at z = 2.8. Spectroscopic follow-up clearly reveals extended Lyα in emission between two images of the central active galactic nucleus (AGN). We reconstruct the lensed quasar host galaxy in the source plane by applying a strong lens model to HST imaging and resolve spatial scales as small as ˜200 pc. In the source plane, we recover the host galaxy morphology to within a few hundred parsecs of the central AGN and map the extended Lyα emission to its physical origin on one side of the host galaxy at radii ˜0.5-2 kpc from the central AGN. There are clear morphological differences between the Lyα and rest-frame ultraviolet stellar continuum emission from the quasar host galaxy. Furthermore, the relative velocity profiles of quasar Lyα, host galaxy Lyα, and metal lines in outflowing gas reveal differences in the absorbing material affecting the AGN and host galaxy. These data indicate the presence of patchy local intervening gas in front of the central quasar and its host galaxy. This interpretation is consistent with the central luminous quasar being obscured across a substantial fraction of its surrounding solid angle, resulting in strong anisotropy in the exposure of the host galaxy to ionizing radiation from the AGN. This work demonstrates the power of strong-lensing-assisted studies to probe spatial scales that are currently inaccessible by other means.

  12. Environments of Nearby Quasars in Sloan Digital Sky Survey

    CERN Document Server

    Lietzen, H; Nurmi, P; Tago, E; Saar, E; Liivamagi, J; Tempel, E; Einasto, M; Einasto, J; Gramann, M; Takalo, L O

    2009-01-01

    For the first time spectroscopic galaxy redshift surveys are reaching the scales where galaxies can be studied together with the nearest quasars. This gives an opportunity to study the dependence between the activity of a quasar and its environment in a more extensive way than before. We study the spatial distribution of galaxies and groups of galaxies in the environments of low redshift quasars in the Sloan Digital Sky Survey (SDSS). Our aim is to understand how the nearby quasars are embedded in the local and global density field of galaxies and how the environment affects quasar activity. We analyse the environments of nearby quasars using number counts of galaxies. We also study the dependence of group properties to their distance to the nearest quasar. The large scale environments are studied by analysing the locations of quasars in the luminosity density field. Our study of the number counts of galaxies in quasar environments shows an underdensity of bright galaxies at a few Mpc from quasars. Also, the ...

  13. Multi-Sightline Observation of Narrow Absorption Lines in Lensed Quasar SDSS J1029+2623

    CERN Document Server

    Misawa, Toru; Charlton, Jane C; Eracleous, Michael; Chartas, George; Bauer, Franz E; Inada, Naohisa; Uchiyama, Hisakazu

    2016-01-01

    We exploit the widely-separated images of the lensed quasar SDSS J1029+2623 ($z_{em}$=2.197, $\\theta =22^{\\prime\\prime}\\!\\!.5$) to observe its outflowing wind through two different sightlines. We present an analysis of three observations, including two with the Subaru telescope in 2010 February (Misawa et al. 2013) and 2014 April (Misawa et al. 2014), separated by 4 years, and one with the Very Large Telescope, separated from the second Subaru observation by $\\sim$2 months. We detect 66 narrow absorption lines (NALs), of which 24 are classified as intrinsic NALs that are physically associated with the quasar based on partial coverage analysis. The velocities of intrinsic NALs appear to cluster around values of $v_{ej}$ $\\sim$ 59,000, 43,000, and 29,000 km/s, which is reminiscent of filamentary structures obtained by numerical simulations. There are no common intrinsic NALs at the same redshift along the two sightlines, implying that the transverse size of the NAL absorbers should be smaller than the sightline...

  14. Restarting radio activity and dust emission in radio-loud broad absorption line quasars

    CERN Document Server

    Bruni, G; Montenegro-Montes, F M; Brienza, M; González-Serrano, J I

    2015-01-01

    Broad absorption line quasars (BAL QSOs) are objects showing absorption from relativistic outflows, with velocities up to 0.2c. These manifest, in about 15% of quasars, as absorption troughs on the blue side of UV emission lines, such as C iv and Mg ii. In this work, we complement the information collected in the cm band for our previously presented sample of radio loud BAL QSOs with new observations at m and mm bands. Our aim is to verify the presence of old, extended radio components in the MHz range, and probe the emission of dust (linked to star formation) in the mm domain. We observed 5 sources from our sample, already presenting hints of low-frequency emission, with the GMRT at 235 and 610 MHz. Other 17 sources (more than half the sample) were observed with bolometer cameras at IRAM-30m and APEX. All sources observed with the GMRT present extended emission at a scale of tens of kpc. In some cases these measurements allow us to identify a second component in the SED, at frequencies below 1.4 GHz, beyond ...

  15. Discovery of Broad Soft X-ray Absorption Lines from the Quasar Wind in PDS 456

    CERN Document Server

    Reeves, James; Nardini, Emanuele; Behar, Ehud; O'Brien, Paul; Tombesi, Francesco; Turner, Tracey Jane; Costa, Michele

    2016-01-01

    High resolution soft X-ray spectroscopy of the prototype accretion disk wind quasar, PDS 456, is presented. Here, the XMM-Newton RGS spectra are analyzed from the large 2013-2014 XMM-Newton campaign, consisting of 5 observations of approximately 100 ks in length. During the last observation (hereafter OBS. E), the quasar is at a minimum flux level and broad absorption line profiles are revealed in the soft X-ray band, with typical velocity widths of $\\sigma_{\\rm v}\\sim 10,000$ km s$^{-1}$. During a period of higher flux in the 3rd and 4th observations (OBS. C and D, respectively), a very broad absorption trough is also present above 1 keV. From fitting the absorption lines with models of photoionized absorption spectra, the inferred outflow velocities lie in the range $\\sim 0.1-0.2c$. The absorption lines likely originate from He and H-like neon and L-shell iron at these energies. Comparison with earlier archival data of PDS 456 also reveals similar absorption structure near 1 keV in a 40 ks observation in 20...

  16. Faraday Rotation Measure Synthesis of intermediate redshift quasars as a probe of intervening matter

    CERN Document Server

    Kim, Kwang Seong; Miniati, Francesco; Bernet, M L; Beck, Rainer; O'Sullivan, S P; Gaensler, B M

    2016-01-01

    There is evidence that magnetized material along the line of sight to distant quasars is detectable in the polarization properties of the background sources, which appear to be correlated with the presence of intervening MgII absorption, which is itself thought to arise in outflowing material from star forming galaxies. In order to investigate this further, we have obtained high spectral resolution polarization measurements, with the VLA and ATCA, of a set of 49 unresolved quasars for which we have high quality optical spectra. These enable us to produce a Faraday Depth spectrum for each source, using Rotation Measure Synthesis. We characterize the complexity of the Faraday Depth spectrum using a number of parameters and show how these are related, or not, to the overall depolarization and to the presence of MgII absorption along the line of sight. Our new independent radio data confirms that interveners are strongly associated with depolarization and also, at lower significance, with the mean Rotation Measur...

  17. PROBING THE FERMI BUBBLES IN ULTRAVIOLET ABSORPTION: A SPECTROSCOPIC SIGNATURE OF THE MILKY WAY'S BICONICAL NUCLEAR OUTFLOW

    Energy Technology Data Exchange (ETDEWEB)

    Fox, Andrew J.; Bordoloi, Rongmon; Hernandez, Svea; Tumlinson, Jason [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Savage, Blair D.; Wakker, Bart P. [Department of Astronomy, University of Wisconsin-Madison, 475 North Charter Street, Madison, WI 53706 (United States); Lockman, Felix J. [National Radio Astronomy Observatory, P.O. Box 2, Rt. 28/92, Green Bank, WV 24944 (United States); Jenkins, Edward B.; Bowen, David V. [Princeton University Observatory, Princeton, NJ 08544 (United States); Bland-Hawthorn, Joss [Institute of Astronomy, School of Physics, University of Sydney, NSW 2006 (Australia); Kim, Tae-Sun [Osservatorio Astronomico di Trieste, Via G.B. Tiepolo 11, I-34143 Trieste (Italy); Benjamin, Robert A., E-mail: afox@stsci.edu [Department of Physics, University of Wisconsin-Whitewater, 800 West Main Street, Whitewater, WI 53190 (United States)

    2015-01-20

    Giant lobes of plasma extend ≈55° above and below the Galactic center, glowing in emission from gamma rays (the Fermi Bubbles) to microwaves and polarized radio waves. We use ultraviolet absorption-line spectra from the Hubble Space Telescope to constrain the velocity of the outflowing gas within these regions, targeting the quasar PDS 456 (ℓ, b = 10.°4, +11.°2). This sightline passes through a clear biconical structure seen in hard X-ray and gamma-ray emission near the base of the northern Fermi Bubble. We report two high-velocity metal absorption components, at v {sub LSR} = –235 and +250 km s{sup –1}, which cannot be explained by co-rotating gas in the Galactic disk or halo. Their velocities are suggestive of an origin on the front and back side of an expanding biconical outflow emanating from the Galactic center. We develop simple kinematic biconical outflow models that can explain the observed profiles with an outflow velocity of ≳900 km s{sup –1} and a full opening angle of ≈110° (matching the X-ray bicone). This indicates Galactic center activity over the last ≈2.5-4.0 Myr, in line with age estimates of the Fermi Bubbles. The observations illustrate the use of UV spectroscopy to probe the properties of swept-up gas venting into the Fermi Bubbles.

  18. Probing the Fermi Bubbles in Ultraviolet Absorption: A Spectroscopic Signature of the Milky Way's Biconical Nuclear Outflow

    CERN Document Server

    Fox, Andrew J; Savage, Blair D; Lockman, Felix J; Jenkins, Edward B; Wakker, Bart P; Bland-Hawthorn, Joss; Hernandez, Svea; Kim, Tae-Sun; Benjamin, Robert A; Bowen, David V; Tumlinson, Jason

    2014-01-01

    Giant lobes of plasma extend 55 degrees above and below the Galactic Center, glowing in emission from gamma rays (the Fermi Bubbles) to microwaves (the WMAP haze) and polarized radio waves. We use ultraviolet absorption-line spectra from the Hubble Space Telescope to constrain the velocity structure of the outflowing gas within these regions, targeting the quasar PDS 456 (Galactic coordinates l,b=10.4, +11.2 degrees). This sightline passes through a clear biconical structure seen in hard X-ray and gamma-ray emission near the base of the northern Fermi Bubble. We report two high-velocity metal absorption components, at v_LSR=-235 and +250 km/s, which cannot be explained by co-rotating gas in the Galactic disk or halo. Their velocities are suggestive of an origin on the front and back side of an expanding biconical outflow emanating from the Galactic Center. We develop simple kinematic biconical outflow models that can explain these observed profiles with an outflow velocity of ~900 km/s and a full opening angl...

  19. Meteorological factors controlling low-level continental pollutant outflow across a coast

    Directory of Open Access Journals (Sweden)

    D. L. Peake

    2014-04-01

    Full Text Available Coastal outflow describes the horizontal advection of pollutants from the continental boundary layer across a coastline into a layer above the marine boundary layer. This process can ventilate polluted continental boundary layers and thus regulate air quality in highly populated coastal regions. This paper investigates the factors controlling coastal outflow and quantifies its importance as a ventilation mechanism. Tracers in the Met Office Unified Model (MetUM are used to examine the magnitude and variability of coastal outflow over the eastern United States for a 4 week period during summer 2004. Over the 4 week period, ventilation of tracer from the continental boundary layer via coastal outflow occurs with the same magnitude as vertical ventilation via convection and advection. The relative importance of tracer decay rate, cross-coastal advection rate, and a parameter based on the relative continental and marine boundary layer heights, on coastal outflow is assessed by reducing the problem to a time-dependent box-model. The ratio of the advection rate and decay rate is a dimensionless parameter which determines whether tracers are long-lived or short-lived. Long- and short-lived tracers exhibit different behaviours with respect to coastal outflow. For short-lived tracers, increasing the advection rate increases the diurnally averaged magnitude of coastal outflow, but has the opposite effect for very long-lived tracers. Short-lived tracers exhibit large diurnal variability in coastal outflow but long-lived tracers do not. By combining the MetUM and box-model simulations a landwidth is determined which represents the distance inland over which emissions contribute significantly to coastal outflow. A landwidth of between 100 and 400 km is found to be representative for a tracer with a lifetime of 24 h.

  20. Adaptive optics imaging of low and intermediate redshift quasars

    CERN Document Server

    Márquez, I; Theodore, B; Bremer, M; Monnet, G; Beuzit, J L

    2001-01-01

    We present the results of adaptive-optics imaging in the H and K bands of 12 low and intermediate redshift (z15.0) themselves as reference for the correction, have typical spatial resolution of FWHM~0.3 arcsec before deconvolution. The deconvolved H-band image of PG1700+514 has a spatial resolution of 0.16 arcsec and reveals a wealth of details on the companion and the host-galaxy. Four out of the twelve quasars have close companions and obvious signs of interactions. The two-dimensional images of three of the host-galaxies unambiguously reveal bars and spiral arms. The morphology of the other objects are difficult to determine from one dimensional surface brightness profile and deeper images are needed. Analysis of mocked data shows that elliptical galaxies are always recognized as such, whereas disk hosts can be missed for small disk scale lengths and large QSO contributions.

  1. Obscuration of Quasars by Dust and the Reddening Mechanism in Parkes-Quasars

    CERN Document Server

    Masci, F J

    1998-01-01

    A majority of quasar surveys have been based on criteria which assume strong blue continua or a UV-excess. Any amount of dust along the line-of-sight is expected to drastically extinguish the optical/UV flux leading to a selection bias. Radio surveys however should suffer no bias against extinction by dust. Recently, a large complete sample of radio-selected quasars has become available (the `Parkes sample'). A majority of these sources exhibit optical--to--near-infrared continua that are exceedingly `red', very unlike those of quasars selected optically. The purpose of this thesis, broadly speaking, is to explore the problem of incompleteness in optical quasar surveys due to obscuration by dust, and to interpret the relatively `red' continua observed in the Parkes quasar sample. The first part of this thesis explores the observational consequences of an intervening (foreground) cosmological dust component, such as that located in galaxies and clusters. The second part examines the continuum properties of Par...

  2. QUality Assessment of System Architectures and their Requirements (QUASAR)

    Science.gov (United States)

    2010-05-18

    2010 Carnegie Mellon University QUality Assessment of System Architectures and their Requirements ( QUASAR ) DoD and NDIA System-of-Systems...Architectures and their Requirements ( QUASAR ) 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e...Prescribed by ANSI Std Z39-18 2 QUASAR Version 3.1, 1 Hour Overview Donald Firesmith, 18 May 2010 © 2010 Carnegie Mellon University Topics History

  3. Double Lobed Radio Quasars from the Sloan Digital Sky Survey

    Energy Technology Data Exchange (ETDEWEB)

    de Vries, W H; Becker, R H; White, R L

    2005-11-10

    We have combined a sample of 44 984 quasars, selected from the Sloan Digital Sky Survey (SDSS) Data Release 3, with the FIRST radio survey. Using a novel technique where the optical quasar position is matched to the complete radio environment within 450'', we are able to characterize the radio morphological make-up of what is essentially an optically selected quasar sample, regardless of whether the quasar (nucleus) itself has been detected in the radio. About 10% of the quasar population have radio cores brighter than 0.75 mJy at 1.4 GHz, and 1.7% have double lobed FR2-like radio morphologies. About 75% of the FR2 sources have a radio core (> 0.75mJy). A significant fraction ({approx}40%) of the FR2 quasars are bent by more than 10 degrees, indicating either interactions of the radio plasma with the ICM or IGM. We found no evidence for correlations with redshift among our FR2 quasars: radio lobe flux densities and radio source diameters of the quasars have similar distributions at low (mean 0.77) and high (mean 2.09) redshifts. Using a smaller high reliability FR2 sample of 422 quasars and two comparison samples of radio-quiet and non-FR2 radio-loud quasars, matched in their redshift distributions, we constructed composite optical spectra from the SDSS spectroscopic data. Based on these spectra we can conclude that the FR2 quasars have stronger high-ionization emission lines compared to both the radio quiet and non-FR2 radio loud sources. This is consistent with the notion that the emission lines are brightened by ongoing shock ionization of ambient gas in the quasar host as the radio source expands.

  4. Hidden blazars and emission line variability of high redshift quasars

    Directory of Open Access Journals (Sweden)

    Feng Ma

    2001-01-01

    Full Text Available We have carried out a survey to search for hidden blazars in a sample of z 2 radio{loud quasars. The idea is based on our prediction that we should be able to see large C IV line variability not associated with observed continuum variations or most other emission lines in every radio{loud quasar. Here we report the initial results including the discovery of large C IV line variations in two quasars.

  5. Do Quasar Ley Lines Really Exist

    Science.gov (United States)

    Webster, A.

    1982-10-01

    The hypothesis that the distribution of the quasars on the celestial sphere contains an unexpectedly large number of well-aligned triples is tested by applying, to the Cerro Tololo objective-prism sample, a shape-statistic which was originally developed to investigate whether neolithic standing stones were deliberately sited on ley lines. It is found that alignment in triples is not a conspicuous feature of the quasars in this sample. The sample does contain one well-aligned triple whose properties resemble those of two triples found earlier in a different field by Arp & Hazard, but the probability of this being a chance alignment is not low. The same authors have noted a total of four well-collimated triples which they consider remarkable, but an approximate probability calculation based on the shape-statistic indicates that they need not have a low probability of occurring by chance.

  6. Spectral Variability in Radio-Loud Quasars

    Indian Academy of Sciences (India)

    Minfeng Gu

    2014-09-01

    The spectral variability of a sample of 44 Flat-Spectrum Radio Quasars (FSRQs) and 18 Steep-Spectrum Radio Quasars (SSRQs) in SDSS stripe 82 region is investigated. Twenty-five of 44 FSRQs show a bluer-when-brighter trend (BWB), while only one FSRQ shows a redder-when-brighter trend, which is in contrast to our previous results. Eight of 18 SSRQs display a BWB. We found an anticorrelation between the Eddington ratio and the variability amplitude in the band for SSRQs, which is similar to that in radio-quiet AGNs. This implies that the thermal emission from the accretion disk may be responsible for the variability in SSRQs. The spectral variability from SDSS multi-epoch spectroscopy also shows BWB for several SSRQs, which is consistent with that from photometry.

  7. Optical Monitoring of Quasars; 1, Variability

    CERN Document Server

    García, A; Jablonski, F J; Terlevich, R J

    1999-01-01

    We present an analysis of quasar variability from data collected during a photometric monitoring of 50 objects carried out at CNPq/Laboratorio Nacional de Astrofisica, Brazil, between March 1993 and July 1996. A distinctive feature of this survey is its photometric accuracy, ~ 0.02 V mag, achieved through differential photometry with CCD detectors, what allows the detection of faint levels of variability. We find that the relative variability, delta = sigma / L, observed in the V band is anti-correlated with both luminosity and redshift, although we have no means of discovering the dominant relation, given the strong coupling between luminosity and redshift for the objects in our sample.We introduce a model for the dependence of quasar variability on frequency that is consistent with multi-wavelength observations of the nuclear variability of the Seyfert galaxy NGC 4151. We show that correcting the observed variability for this effect slightly increases the significance of the trends of variability with lumin...

  8. Large groups in the Chile-UK quasar survey

    CERN Document Server

    Newman, P R; Campusano, L E; Graham, M J; Newman, Peter R.; Clowes, Roger G.; Campusano, Luis E.; Graham, Matthew J.

    1997-01-01

    The Chile-UK quasar survey, a new-generation 140 deg^2 UVX survey to B = 20, is now \\sim 25 per cent complete. The catalogue currently contains 319 quasars and 93 emission line galaxies. Using the minimal-spanning tree method, we have independently confirmed the \\sim 200 h^-1 Mpc group of quasars at z \\simeq 1.3 discovered by Clowes & Campusano (1991). We have discovered a new \\sim 150 h^-1 Mpc group of 13 quasars at median z \\simeq 1.51. The null hypothesis of a uniform, random distribution is rejected at a level of significance of 0.003 for both groups.

  9. Physical properties of absorbers in high redshift quasars

    Directory of Open Access Journals (Sweden)

    L. E. Simon

    2007-01-01

    Full Text Available Recent studies based on quasar emission lines suggest that quasar environments are typicaly metal rich, with metallicities near or above the solar value at even the highest observed redshifts. Due to the large uncertainties in- herent in emission line abundance analysis, we employ another technique, absorption line analysis, to corroborate the evidence gleaned so far in order to better constrain the de- tected metallicities. We are also interested in the physical nature of these absorbers, their relationship to quasar outows, and their role in quasar-host galaxy evolution.

  10. DETECTION OF REST-FRAME OPTICAL LINES FROM X-SHOOTER SPECTROSCOPY OF WEAK EMISSION-LINE QUASARS

    Energy Technology Data Exchange (ETDEWEB)

    Plotkin, Richard M.; Gallo, Elena [Department of Astronomy, University of Michigan, 1085 South University Avenue, Ann Arbor, MI 48109 (United States); Shemmer, Ohad [Department of Physics, University of North Texas, Denton, TX 76203 (United States); Trakhtenbrot, Benny [Institute for Astronomy, Department of Physics, ETH Zurich, Wolfgang-Pauli-Strasse 27, CH-8093 Zurich (Switzerland); Anderson, Scott F. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Brandt, W. N.; Luo, Bin; Schneider, Donald P. [Department of Astronomy and Astrophysics, 525 Davey Lab, The Pennsylvania State University, University Park, PA 16802 (United States); Fan, Xiaohui [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Lira, Paulina [Departamento de Astronomia, Universidad de Chile, Camino del Observatorio 1515, Santiago (Chile); Richards, Gordon T. [Department of Physics, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104 (United States); Strauss, Michael A. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Wu, Jianfeng, E-mail: rplotkin@umich.edu [Harvard-Smithsonian Center for Astrophysics, MS 6, 60 Garden Street Cambridge, MA 02138 (United States)

    2015-06-01

    Over the past 15 yr, examples of exotic radio-quiet quasars with intrinsically weak or absent broad emission line regions (BELRs) have emerged from large-scale spectroscopic sky surveys. Here, we present spectroscopy of seven such weak emission line quasars (WLQs) at moderate redshifts (z = 1.4–1.7) using the X-shooter spectrograph, which provides simultaneous optical and near-infrared spectroscopy covering the rest-frame ultraviolet (UV) through optical. These new observations effectively double the number of WLQs with spectroscopy in the optical rest-frame, and they allow us to compare the strengths of (weak) high-ionization emission lines (e.g., C iv) to low-ionization lines (e.g., Mg ii, Hβ, Hα) in individual objects. We detect broad Hβ and Hα emission in all objects, and these lines are generally toward the weaker end of the distribution expected for typical quasars (e.g., Hβ has rest-frame equivalent widths ranging from 15–40 Å). However, these low-ionization lines are not exceptionally weak, as is the case for high-ionization lines in WLQs. The X-shooter spectra also display relatively strong optical Fe ii emission, Hβ FWHM ≲ 4000 km s{sup −1}, and significant C iv blueshifts (≈1000–5500 km s{sup −1}) relative to the systemic redshift; two spectra also show elevated UV Fe ii emission, and an outflowing component to their (weak) Mg ii emission lines. These properties suggest that WLQs are exotic versions of “wind-dominated” quasars. Their BELRs either have unusual high-ionization components, or their BELRs are in an atypical photoionization state because of an unusually soft continuum.

  11. An X-Ray Study of Lobe-Dominated Radio-Loud Quasars with XMM-Newton

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    We report on our results of X-ray spectral analysis for a sample of radio-loud quasars covering a wide range of the radio core-dominance parameter, R, from core-dominated to lobe-dominated objects, using data obtained mostly with the XMM-Newton Observatory. We find that the spectral shape of the underlying power-law continuum is flat even for the lobe-dominated objects (average photon index ~ 1.5), indistinguishable from that of core-dominated quasars. For lobe-dominated objects, contribution of X-rays from the jets is expected to be very small based on previous unification schemes, more than one order of magnitude lower than the observed X-ray luminosities. Assuming that radio-loud quasars follow the same X-ray-UV/optical luminosity relation for the disk-corona emission as found for radio-quiet quasars, we estimate the X-ray flux contributed by the disk-corona component from the optical/UV continuum. We find that neither the luminosity, nor the spectral shape, of the disk-corona X-ray emission can account for the bulk of the observed X-ray properties. Thus in lobe-dominated quasars, either the disk-corona X-ray emission is much enhanced in strength and flatter in spectral shape (photon index~1.5) compared to normal radio-quiet quasars, or their jet X-ray emission is much enhanced compared to their weak radio core-jet emission. If the latter is the case, our result may imply that the jet emission in X-rays is less Doppler beamed than that in the radio. As a demonstrating example, we test this hypothesis by using a specific model in which the X-ray jet has a larger opening angle than the radio jet.

  12. A Model for Intrinsic Redshifts of Quasars

    CERN Document Server

    Hansen, Peter M

    2015-01-01

    The large observed redshift of quasars has suggested large cosmological distances and a corresponding enormous energy output to explain the brightness or luminosity as seen at earth. Alternative or complementary sources of redshift have not been identified by the astronomical community. This study examines one possible source of additional redshift: an intrinsic component based on the plasma characteristics of high temperature and high electron density which are believed to be present.

  13. X-ray emission from red quasars

    Science.gov (United States)

    Bregman, J. N.; Glassgold, A. E.; Huggins, P. J.; Kinney, A. L.

    1985-01-01

    A dozen red quasars were observed with the Einstein Observatory in order to determine their X-ray properties. The observations show that for all these sources, the infrared-optical continuum is so steep that when extrapolated to higher frequencies, it passes orders of magnitude below the measured X-ray flux. The X-ray emission is better correlated with the radio than with the infrared flux, suggesting a connection between the two. By applying the synchrotron-self-Compton model to the data, it is found that the infrared-optical region has a size of 0.01 pc or more and a magnetic field more than 0.1 G, values considerably different than are found in the radio region. Unlike other quasars, the ionizing continuum is dominated by the X-ray emission. The peculiar line ratios seen in these objects can be understood with a photoionization model, provided that the photon to gas density ratio (ionization parameter) is an order of magnitude less than in typical quasars.

  14. Quasar Selection Based on Photometric Variability

    CERN Document Server

    MacLeod, C L; Ivezic, Z; Kochanek, C S; Gibson, R; Meisner, A; Kozlowski, S; Sesar, B; Becker, A C; de Vries, W

    2010-01-01

    We develop a method for separating quasars from other variable point sources using SDSS Stripe 82 light curve data for ~10,000 variable objects. To statistically describe quasar variability, we use a damped random walk model parametrized by a damping time scale, tau, and an asymptotic amplitude (structure function), SF_inf. With the aid of an SDSS spectroscopically confirmed quasar sample, we demonstrate that variability selection in typical extragalactic fields with low stellar density can deliver complete samples with reasonable purity (or efficiency, E). Compared to a selection method based solely on the slope of the structure function, the inclusion of the tau information boosts E from 60% to 75% while maintaining a highly complete sample (98%) even in the absence of color information. For a completeness of C=90%, E is boosted from 80% to 85%. Conversely, C improves from 90% to 97% while maintaining E=80% when imposing a lower limit on tau. With the aid of color selection, the purity can be further booste...

  15. Fe II Diagnostic Tools for Quasars

    CERN Document Server

    Verner, E; Verner, D; Johansson, S; Kallman, T; Gull, T R

    2004-01-01

    The enrichment of Fe, relative to alpha-elements such as O and Mg, represents a potential means to determine the age of quasars and probe the galaxy formation epoch. To explore how \\ion{Fe}{2} emission in quasars is linked to physical conditions and abundance, we have constructed a 830-level \\ion{Fe}{2} model atom and investigated through photoionization calculations how \\ion{Fe}{2} emission strengths depend on non-abundance factors. We have split \\ion{Fe}{2} emission into three major wavelength bands, \\ion{Fe}{2} (UV), \\ion{Fe}{2}(Opt1), and \\ion{Fe}{2}(Opt2), and explore how the \\ion{Fe}{2}(UV)/\\ion{Mg}{2}, \\ion{Fe}{2}(UV)/\\ion{Fe}{2}(Opt1) and \\ion{Fe}{2}(UV)/\\ion{Fe}{2}(Opt2) emission ratios depend upon hydrogen density and ionizing flux in broad-line regions (BLR's) of quasars. Our calculations show that: 1) similar \\ion{Fe}{2}(UV)/\\ion{Mg}{2} ratios can exist over a wide range of physical conditions; 2) the \\ion{Fe}{2}(UV)/\\ion{Fe}{2}(Opt1) and \\ion{Fe}{2}(UV)/\\ion{Fe}{2}(Opt2) ratios serve to constrain...

  16. Accretion and Outflow Activity in Brown Dwarfs

    CERN Document Server

    Riaz, B

    2013-01-01

    An investigation of the magnetospheric accretion and outflow signatures in sub-stellar objects is a natural extension of similar studies conducted on classical T Tauri stars (CTTS), and helps understand if brown dwarfs (BDs) follow the same formation mechanism as stars. Over the past decade, evidence for accretion in very low-mass stars (VLMs) and BDs has been accumulated using various techniques, which indicates that the overall accretion characteristics are continuous across the sub-stellar boundary. Outflow activity in VLMs and BDs has been confirmed based on spectro-astrometry of forbidden emission lines observed in the optical, and in millimetre continuum images of CO J=2-1 emission. This review summarizes the past and current state of observational work on accretion and outflow activity in VLMs and BDs, particularly with the advent of new instruments such as VLT/X-Shooter which has allowed the study of several accretion and outflow indicators over a wider wavelength range.

  17. Disks, accretion and outflows of brown dwarfs

    CERN Document Server

    Joergens, V; Liu, Y; Pascucci, I; Whelan, E; Alcala, J; Biazzo, K; Costigan, G; Gully-Santiago, M; Henning, Th; Natta, A; Rigliaco, E; Rodriguez-Ledesma, V; Sicilia-Aguilar, A; Tottle, J; Wolf, S

    2012-01-01

    Characterization of the properties of young brown dwarfs are important to constraining the formation of objects at the extreme low-mass end of the IMF. While young brown dwarfs share many properties with solar-mass T Tauri stars, differences may be used as tests of how the physics of accretion/outflow and disk chemistry/dissipation depend on the mass of the central object. This article summarizes the presentations and discussions during the splinter session on 'Disks, accretion and outflows of brown dwarfs' held at the CoolStars17 conference in Barcelona in June 2012. Recent results in the field of brown dwarf disks and outflows include the determination of brown dwarf disk masses and geometries based on Herschel far-IR photometry (70-160 um), accretion properties based on X-Shooter spectra, and new outflow detections in the very low-mass regime.

  18. Electron-positron outflow from black holes

    CERN Document Server

    Van Putten, M H P M

    2000-01-01

    Gamma-ray bursts (GRBs) appear as the brightest transient phenomena in the Universe. The nature of the central engine in GRBs is a missing link in the theory of fireballs to their stellar mass progenitors. Here it is shown that rotating black holes produce electron-positron outflow when brought into contact with a strong magnetic field. The outflow is produced by a coupling of the spin of the black hole to the orbit of the particles. For a nearly extreme Kerr black hole, particle outflow from an initial state of electrostatic equilibrium has a normalized isotropic emission of $\\sim external magnetic field strength, B_c=4.4 x 10^{13}G, and M is the mass of the black hole. This initial outflow has a half-opening angle given.

  19. Large sea ice outflow into the Nares Strait in 2007

    DEFF Research Database (Denmark)

    Kwok, R.; Pedersen, L.T.; Gudmandsen, Preben

    2010-01-01

    ice in the 13-year record between 1997 and 2009. The 2007 area and volume outflows of 87 x 10(3) km(2) and 254 km(3) are more than twice their 13-year means. This contributes to the recent loss of the thick, multiyear Arctic sea ice and represents similar to 10% of our estimates of the mean ice export......Sea ice flux through the Nares Strait is most active during the fall and early winter, ceases in mid- to late winter after the formation of ice arches along the strait, and re-commences after breakup in summer. In 2007, ice arches failed to form. This resulted in the highest outflow of Arctic sea...... at Fram Strait. Clearly, the ice arches control Arctic sea ice outflow. The duration of unobstructed flow explains more than 84% of the variance in the annual area flux. In our record, seasonal stoppages are always associated with the formation of an arch near the same location in the southern Kane Basin...

  20. Revisiting the extremely fast disc wind in a gravitationally lensed quasar APM 08279+5255

    CERN Document Server

    Hagino, Kouichi; Odaka, Hirokazu; Watanabe, Shin; Takahashi, Tadayuki

    2016-01-01

    The gravitationally lensed quasar APM 08279+5255 has the fastest claimed AGN wind, with velocities of 0.6--0.7c. This would require magnetic driving mechanism since this exceeds the radiation drag limit for any radiation driving. This conclusion derives from interpreting both the narrow and broad absorption features in the X-ray spectrum as iron absorption lines. However, the classic ultrafast outflow source PDS 456 also shows similar absorption systems, but here the higher energy, broader feature is generally interpreted as a more complex absorption edge. We reanalyse all the spectra from APM 08279+5255 using a full 3-dimensional Monte Carlo radiative transfer disc wind model for the ionised wind at 0.1--0.2c, together with complex absorption from lower ionisation material, and find that this is a better description of the data. Thus there is no strong requirement for outflow velocities beyond 0.2c, which can be powered by radiation driving. We show that UV line driving is especially likely given the spectra...

  1. Broad-band short term X-ray spectral variability of the quasar PDS 456

    Science.gov (United States)

    Matzeu, G.; Reeves, J.; Nardini, E.; Braito, V.; Costa, M.; Tombesi, F.

    2015-07-01

    We present an analysis of a recent 500 ks Suzaku observation, carried out in 2013, of the nearby (z=0.184) luminous (L_{bol}˜10^{47} erg s^{-1}) quasar PDS 456 in which the X-ray flux was unusually low. Short term X-ray spectral variability has been detected, which may be caused by two variable coverers of column density log (N_{H,1}/cm^{-2})=22.3±0.1 and log (N_{H,2}/cm(-2) )=23.2±0.1 We find that the partial covering requires an outflow velocity of ˜0.25 c, coincident with the velocity of the highly ionised outflow at the 99.9 % confidence level. Therefore the partial covering clouds could be the denser clumpy part of an inhomogeneous wind. An obscuration event occurs 1250 ks into the observation, where the spectrum becomes totally opaque at Fe K. This implies that the size of the absorber and likewise the X-ray emitter, to be less than 20 Rg. We also analyse the flaring behaviour in the lightcurve. The behaviour of the soft and hard X-ray flux, suggested a corona characterised by an extended "warm" region of ˜20 Rg in size combined with more compact regions of "hot" electrons of ˜8 Rg in size.

  2. The warm absorber in the radio-loud quasar 4C +74.26

    CERN Document Server

    Di Gesu, L

    2016-01-01

    Outflows of photoionized gas are commonly detected in the X-ray spectra of Seyfert 1 galaxies. However, the evidence for this phenomenon in broad line radio galaxies, which are analogous to Seyfert 1 galaxies in the radio-loud regime, has so far been scarce. Here, we present the analysis of the X-ray absorption in the radio-loud quasar 4C +74.26. With the aim of characterizing the kinetic and the ionization conditions of the absorbing material, we fitted jointly the XMM-Newton Reflection Grating Spectrometer (RGS) and the Chandra High Energy Transmission Grating Spectrometer (HETGS) spectra, which were taken 4 months apart. The intrinsic continuum flux did not vary significantly during this time lapse. The spectrum shows the absorption signatures (e.g., Fe-UTA, \\ion{O}{vii}, and \\ion{Ne}{vii}--\\ion{Ne}{x}) of a photoionized gas outflow ($N_{\\rm H} \\sim 3.5 \\times 10^{21} \\rm cm^{-2}$, $\\log \\xi \\sim 2.6$, $v_{\\rm out}\\sim 3600 \\, \\rm km \\, s^{-1}$) located at the redshift of source. We estimate that the gas i...

  3. Detection of CO Outflow in Rotating Cores

    Institute of Scientific and Technical Information of China (English)

    Xin Guan; Yue-Fang Wu

    2008-01-01

    We investigate the effect of bulk motion on the detection of molecular outflows in the sources S 146, GGD27, and IRAS 22566+5830. The traditional techniques do allow for bulk motions or systematic VLSR shifts of the core emissions, which may cause contamination of the high velocity gas emissions, and outflows may either fail to be detected or have their properties miscalculated. We used a program to follow the systematic shift of VLSR and better results have been obtained.

  4. Radiative transfer in ultra-relativistic outflows

    OpenAIRE

    Beloborodov, Andrei M.

    2010-01-01

    Analytical and numerical solutions are obtained for the equation of radiative transfer in ultra-relativistic opaque jets. The solution describes the initial trapping of radiation, its adiabatic cooling, and the transition to transparency. Two opposite regimes are examined: (1) Matter-dominated outflow. Surprisingly, radiation develops enormous anisotropy in the fluid frame before decoupling from the fluid. The radiation is strongly polarized. (2) Radiation-dominated outflow. The transfer occu...

  5. The Large Sky Area Multi-Object Fiber Spectroscopic Telescope Quasar Survey: Quasar Properties from First Data Release

    CERN Document Server

    Ai, Y L; Yang, Jinyi; Yang, Qian; Wang, Feige; Guo, Rui; Zuo, Wenwen; Dong, Xiaoyi; Zhang, Y -X; Yuan, H -L; Song, Y -H; Wang, Jianguo; Dong, Xiaobo; Yang, M; Wu, H; Shen, S -Y; Shi, J -R; He, B -L; Lei, Y -J; Li, Y -B; Luo, A -L; Zhao, Y -H; Zhang, Hao-Tong

    2015-01-01

    We present preliminary results of the quasar survey in Large Sky Area Multi- Object Fiber Spectroscopic Telescope (LAMOST) first data release (DR1), which includes pilot survey and the first year regular survey. There are 3921 quasars identified with reliability, among which 1180 are new quasars discovered in the survey. These quasars are at low to median redshifts, with highest z of 4.83. We compile emission line measurements around the H{\\alpha}, H{\\beta}, Mg II, and C IV regions for the new quasars. The continuum luminosities are inferred from SDSS photo- metric data with model fitting as the spectra in DR1 are non-flux-calibrated. We also compile the virial black hole mass estimates, and flags indicating the selec- tion methods, broad absorption line quasars. The catalog and spectra for these quasars are available online. 28% of the 3921 quasars are selected with optical- infrared colours independently, indicating that the method is quite promising in completeness of quasar survey. LAMOST DR1 and the on-g...

  6. The Multi-Wavelength Quasar Survey Ⅲ.Quasars in Field 836

    Institute of Scientific and Technical Information of China (English)

    Yu Bai; Yang Chen; Xiang-Tao He; Jiang-Hua Wu; Qing-Kang Li; Richard F.Green; Wolfgang Voges

    2007-01-01

    This is the third Paper in a series connected with our Multiwavelength Quasar Survey.The survey is aimed to provide a quasar sample more complete than any previous survey by using a combined selection technique to reduce selection effects.we present the observational results for the X-ray candidates in field f836.We found 15 X-ray AGNs in this field of which eight are new discoveries.The X-ray data and optical spectra of these AGNs are given.We give the X-ray candidate selection criteria.which proved to be highly efficient in isolating X-ray AGNs.

  7. Quantifying Supernovae-driven Multiphase Galactic Outflows

    Science.gov (United States)

    Li, Miao; Bryan, Greg L.; Ostriker, Jeremiah P.

    2017-06-01

    Galactic outflows are observed everywhere in star-forming disk galaxies and are critical for galaxy formation. Supernovae (SNe) play the key role in driving the outflows, but there is no consensus as to how much energy, mass, and metal they can launch out of the disk. We perform 3D, high-resolution hydrodynamic simulations to study SNe-driven outflows from stratified media. Assuming the SN rate scales with gas surface density Σgas as in the Kennicutt-Schmidt relation, we find that the mass loading factor, η m, defined as the mass outflow flux divided by the star formation surface density, decreases with increasing Σgas as {η }{{m}}\\propto {{{Σ }}}{gas}-0.61. Approximately Σgas ≲ 50 M ⊙ pc-2 marks when η m ≳ 1. About 10%-50% of the energy and 40%-80% of the metals produced by SNe end up in the outflows. The tenuous hot phase (T > 3 × 105 K), which fills 60%-80% of the volume at the midplane, carries the majority of the energy and metals in the outflows. We discuss how various physical processes, including the vertical distribution of SNe, photoelectric heating, external gravitational field, and SN rate, affect the loading efficiencies. The relative scale height of gas and SNe is a very important factor in determining the loading efficiencies.

  8. Quantifying Supernovae-Driven Multiphase Galactic Outflows

    CERN Document Server

    Li, Miao; Ostriker, Jeremiah P

    2016-01-01

    Galactic outflows are ubiquitously observed in star-forming disk galaxies and are critical for galaxy formation. Supernovae (SNe) play the key role in driving the outflows, but there is no consensus as to how much energy, mass and metal they can launch out of the disk. We perform 3D, high-resolution hydrodynamic simulations to study SNe-driven outflows from stratified media. Assuming SN rate scales with gas surface density $\\Sigma_{\\rm{gas}}$ as in the Kennicutt-Schmidt (KS) relation, we find the mass loading factor, defined as the mass outflow flux divided by the star formation surface density, decreases with increasing $\\Sigma_{\\rm{gas}}$ as $\\propto \\Sigma^{-0.61}_{\\rm{gas}}$. Approximately $\\Sigma_{\\rm{gas}} \\lesssim$ 50 $M_\\odot/pc^2$ marks when the mass loading factor $\\gtrsim$1. About 10-50\\% of the energy and 40-80\\% of the metals produced by SNe end up in the outflows. The tenuous hot phase ($T>3\\times 10^5$ K) carries the majority of the energy and metals in outflows. We discuss how various physical...

  9. Theory of photospheric emission from relativistic outflows

    CERN Document Server

    Ruffini, R; Vereshchagin, G V

    2013-01-01

    (shortened) In this paper we reexamine the optical depth of ultrarelativistic spherically symmetric outflows and reevaluate the photospheric radius for each model during both the acceleration and coasting phases. It is shown that for both the wind and the shell models there are two asymptotic solutions for the optical depth during the coasting phase of the outflow. In particular we show that quite counterintuitively a geometrically thin shell may appear as a thick wind for photons propagating inside it. For this reason we introduce notions of photon thick and photon thin outflows, which appear more general and better physically motivated with respect to winds and shells. Photosphere of relativistic outflow is a dynamic surface. We study its geometry and find that the photosphere of photon thin outflow has always a convex shape, while in the photon thick one it is initially convex (there is always a photon thin layer in any outflow) and then it becomes concave asymptotically approaching the photosphere of an i...

  10. Fast cold gas in hot AGN outflows

    CERN Document Server

    Costa, Tiago; Haehnelt, Martin

    2014-01-01

    Observations of the emission from spatially extended cold gas around bright high-redshift QSOs reveal surprisingly large velocity widths exceeding 2000 km s^(-1), out to projected distances as large as 30 kpc. The high velocity widths have been interpreted as the signature of powerful AGN-driven outflows. Naively, these findings appear in tension with hydrodynamic models in which AGN-driven outflows are energy-driven and thus very hot with typical temperatures T = 10^6-7 K. Using the moving-mesh code Arepo, we perform 'zoom-in' cosmological simulations of a z = 6 QSO and its environment, following black hole growth and feedback via energy-driven outflows. In the simulations, the QSO host galaxy is surrounded by a clumpy circum-galactic medium pre-enriched with metals due to supernovae-driven galactic outflows. As a result, part of the AGN-driven hot outflowing gas can cool radiatively, leading to large amounts (> 10^9 M_sun) of cold gas comoving with the hot bipolar outflow. This results in velocity widths of...

  11. Production of all $r$-process nuclides by black hole accretion disk outflows from neutron star mergers

    CERN Document Server

    Wu, Meng-Ru; Martínez-Pinedo, Gabriel; Metzger, Brian D

    2016-01-01

    We consider $r$-process nucleosynthesis in outflows from black hole accretion disks formed in double neutron star and neutron star - black hole mergers. These outflows, powered by angular momentum transport processes and nuclear recombination, represent an important -- and in some cases dominant -- contribution to the total mass ejected by the merger. Here we calculate the nucleosynthesis yields from disk outflows using thermodynamic trajectories from hydrodynamic simulations, coupled to a nuclear reaction network. We find that outflows produce a robust abundance pattern around the second $r$-process peak (mass number $A \\sim 130$), independent of model parameters, with significant production of $A < 130$ nuclei. This implies that dynamical ejecta with high electron fraction may not be required to explain the observed abundances of $r$-process elements in metal poor stars. Disk outflows reach the third peak ($ A \\sim 195$) in most of our simulations, although the amounts produced depend sensitively on the ...

  12. Helium Reionization Simulations. I. Modeling Quasars as Radiation Sources

    Science.gov (United States)

    La Plante, Paul; Trac, Hy

    2016-09-01

    We introduce a new project to understand helium reionization using fully coupled N-body, hydrodynamics, and radiative transfer simulations. This project aims to capture correctly the thermal history of the intergalactic medium as a result of reionization and make predictions about the Lyα forest and baryon temperature-density relation. The dominant sources of radiation for this transition are quasars, so modeling the source population accurately is very important for making reliable predictions. In this first paper, we present a new method for populating dark matter halos with quasars. Our set of quasar models includes two different light curves, a lightbulb (simple on/off) and symmetric exponential model, and luminosity-dependent quasar lifetimes. Our method self-consistently reproduces an input quasar luminosity function given a halo catalog from an N-body simulation, and propagates quasars through the merger history of halo hosts. After calibrating quasar clustering using measurements from the Baryon Oscillation Spectroscopic Survey, we find that the characteristic mass of quasar hosts is {M}h˜ 2.5× {10}12 {h}-1 {M}⊙ for the lightbulb model, and {M}h˜ 2.3× {10}12 {h}-1 {M}⊙ for the exponential model. In the latter model, the peak quasar luminosity for a given halo mass is larger than that in the former, typically by a factor of 1.5-2. The effective lifetime for quasars in the lightbulb model is 59 Myr, and in the exponential case, the effective time constant is about 15 Myr. We include semi-analytic calculations of helium reionization, and discuss how to include these quasars as sources of ionizing radiation for full hydrodynamics with radiative transfer simulations in order to study helium reionization.

  13. THE z = 5 QUASAR LUMINOSITY FUNCTION FROM SDSS STRIPE 82

    Energy Technology Data Exchange (ETDEWEB)

    McGreer, Ian D.; Fan Xiaohui [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721-0065 (United States); Jiang Linhua [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287 (United States); Richards, Gordon T. [Department of Physics, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104 (United States); Strauss, Michael A. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Ross, Nicholas P.; White, Martin [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 92420 (United States); Shen Yue [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Schneider, Donald P.; Brandt, W. Niel [Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States); Myers, Adam D. [Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071 (United States); DeGraf, Colin [McWilliams Center for Cosmology, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213 (United States); Glikman, Eilat [Department of Physics and Yale Center for Astronomy and Astrophysics, Yale University, P.O. Box 208121, New Haven, CT 06520-8121 (United States); Ge Jian [Department of Astronomy, University of Florida, 211 Bryant Space Science Center, Gainesville, FL 32611 (United States); Streblyanska, Alina, E-mail: imcgreer@as.arizona.edu [Instituto de Astrofisica de Canarias (IAC), E-38200 La Laguna, Tenerife (Spain)

    2013-05-10

    We present a measurement of the Type I quasar luminosity function at z = 5 using a large sample of spectroscopically confirmed quasars selected from optical imaging data. We measure the bright end (M{sub 1450} < -26) with Sloan Digital Sky Survey (SDSS) data covering {approx}6000 deg{sup 2}, then extend to lower luminosities (M{sub 1450} < -24) with newly discovered, faint z {approx} 5 quasars selected from 235 deg{sup 2} of deep, coadded imaging in the SDSS Stripe 82 region (the celestial equator in the Southern Galactic Cap). The faint sample includes 14 quasars with spectra obtained as ancillary science targets in the SDSS-III Baryon Oscillation Spectroscopic Survey, and 59 quasars observed at the MMT and Magellan telescopes. We construct a well-defined sample of 4.7 < z < 5.1 quasars that is highly complete, with 73 spectroscopic identifications out of 92 candidates. Our color selection method is also highly efficient: of the 73 spectra obtained, 71 are high-redshift quasars. These observations reach below the break in the luminosity function (M{sub 1450}{sup *}{approx}-27). The bright-end slope is steep ({beta} {approx}< -4), with a constraint of {beta} < -3.1 at 95% confidence. The break luminosity appears to evolve strongly at high redshift, providing an explanation for the flattening of the bright-end slope reported previously. We find a factor of {approx}2 greater decrease in the number density of luminous quasars (M{sub 1450} < -26) from z = 5 to z = 6 than from z = 4 to z = 5, suggesting a more rapid decline in quasar activity at high redshift than found in previous surveys. Our model for the quasar luminosity function predicts that quasars generate {approx}30% of the ionizing photons required to keep hydrogen in the universe ionized at z = 5.

  14. ALMA Examines a Distant Quasar Host

    Science.gov (United States)

    Kohler, Susanna

    2017-04-01

    The dust continuum (top) and the [CII] emission (bottom) maps for the region around J1120+0641. [Adapted from Venemans et al. 2017]A team of scientists has used the Atacama Large Millimeter/submillimeter Array (ALMA) to explore the host galaxy of the most distant quasar known. Their observations may help us to build a picture of how the first supermassive black holes in the universe formed and evolved.Faraway Monsters and Their GalaxiesWe know that quasars the incredibly luminous and active centers of some distant galaxies are powered by accreting, supermassive black holes. These monstrous powerhouses have been detected out to redshifts of z 7, when the universe was younger than a billion years old.Though weve observed over a hundred quasars at high redshift, we still dont understand how these early supermassive black holes formed, or whether the black holes and the galaxies that host them co-evolved. In order to answer questions like these, however, we first need to gather information about the properties and behavior of various supermassive black holes and their host galaxies.A team of scientists led by Bram Venemans (Max-Planck Institute for Astronomy, Germany) recently used the unprecedented sensitivity and angular resolution of ALMA as well as the Very Large Array and the IRAM Plateau de Bure Interferometer to examine the most distant quasar currently known, J1120+0641, located at a redshift of z = 7.1.A High-Resolution LookThe teams observations of the dust and gas emission from the quasars host galaxy revealed a number of intriguing things:The red and blue sides of the [CII] emission line are shown here as contours, demonstrating that theres no ordered rotational motion of the gas on kpc scales. [Adapted from Venemans et al. 2017]The majority of the galaxys emission is very compact. Around 80% of the observed flux came from a region of only 11.5 kpc in diameter.Despite the fact that the 2.4-billion-solar-mass black hole at the galaxys center is accreting at

  15. Active Galactic Nuclei Feedback and Galactic Outflows

    Science.gov (United States)

    Sun, Ai-Lei

    Feedback from active galactic nuclei (AGN) is thought to regulate the growth of supermassive black holes (SMBHs) and galaxies. The most direct evidence of AGN feedback is probably galactic outflows. This thesis addresses the link between SMBHs and their host galaxies from four different observational perspectives. First, I study the local correlation between black hole mass and the galactic halo potential (the MBH - Vc relation) based on Very Large Array (VLA) HI observations of galaxy rotation curves. Although there is a correlation, it is no tighter than the well-studied MBH - sigma* relation between the black hole mass and the potential of the galactic bulge, indicating that physical processes, such as feedback, could link the evolution of the black hole to the baryons in the bulge. In what follows, I thus search for galactic outflows as direct evidence of AGN feedback. Second, I use the Atacama Large Millimeter Array (ALMA) to observe a luminous obscured AGN that hosts an ionized galactic outflow and find a compact but massive molecular outflow that can potentially quench the star formation in 10. 6 years.The third study extends the sample of known ionized outflows with new Magellan long-slit observations of 12 luminous obscured AGN. I find that most luminous obscured AGN (Lbol > 1046 ergs s-1) host ionized outflows on 10 kpc scales, and the size of the outflow correlates strongly with the luminosity of the AGN. Lastly, to capitalize on the power of modern photometric surveys, I experiment with a new broadband imaging technique to study the morphology of AGN emission line regions and outflows. With images from the Sloan Digital Sky Survey (SDSS), this method successfully constructs images of the [OIII]lambda5007 emission line and reveals hundreds of extended emission-line systems. When applied to current and future surveys, such as the Large Synoptic Survey Telescope (LSST), this technique could open a new parameter space for the study of AGN outflows. In

  16. A robust measurement of the mass outflow rate of the galactic outflow from NGC 6090

    Science.gov (United States)

    Chisholm, John; Tremonti Christy, A.; Leitherer, Claus; Chen, Yanmei

    2016-11-01

    To evaluate the impact of stellar feedback, it is critical to estimate the mass outflow rates of galaxies. Past estimates have been plagued by uncertain assumptions about the outflow geometry, metallicity, and ionization fraction. Here we use Hubble Space Telescope ultraviolet spectroscopic observations of the nearby starburst NGC 6090 to demonstrate that many of these quantities can be constrained by the data. We use the Si IV absorption lines to calculate the scaling of velocity (v), covering fraction (Cf), and density with distance from the starburst (r), assuming the Sobolev optical depth and a velocity law of the form: v ∝ (1 - Ri/r)β (where Ri is the inner outflow radius). We find that the velocity (β = 0.43) is consistent with an outflow driven by an r-2 force with the outflow radially accelerated, while the scaling of the covering fraction (Cf ∝ r-0.82) suggests that cool clouds in the outflow are in pressure equilibrium with an adiabatically expanding medium. We use the column densities of four weak metal lines and CLOUDY photoionization models to determine the outflow metallicity, the ionization correction, and the initial density of the outflow. Combining these values with the profile fitting, we find Ri = 63 pc, with most of the mass within 300 pc of the starburst. Finally, we find that the maximum mass outflow rate is 2.3 M⊙ yr-1 and the mass-loading factor (outflow divided by the star formation rate) is 0.09, a factor of 10 lower than the value calculated using common assumptions for the geometry, metallicity, and ionization structure of the outflow.

  17. The Sloan Digital Sky Survey quasar catalog: tenth data release

    CERN Document Server

    Pâris, Isabelle; Aubourg, Éric; Ross, Nicholas P; Myers, Adam D; Streblyanska, Alina; Bailey, Stephen; Hall, Patrick B; Strauss, Michael A; Anderson, Scott F; Bizyaev, Dmitry; Borde, Arnaud; Brinkmann, Jon; Bovy, Jo; Brandt, William N; Brewington, Howard; Brownstein, Joel R; Cook, Benjamin A; Ebelke, Garrett; Fan, Xiaohui; Ak, Nurten Filiz; Finley, Hayley; Font-Ribera, Andreu; Ge, Jian; Hamann, Fred; Ho, Shirley; Jiang, Linhua; Kinemuchi, Karen; Malanushenko, Elena; Malanushenko, Viktor; Marchante, Moses; McGreer, Ian D; McMahon, Richard G; Miralda-Escudé, Jordi; Muna, Demitri; Noterdaeme, Pasquier; Oravetz, Daniel; Palanque-Delabrouille, Nathalie; Pan, Kaike; Perez-Fournon, Ismaël; Pieri, Matthew; Riffel, Rogério; Schlegel, David J; Schneider, Donald P; Simmons, Audrey; Viel, Matteo; Weaver, Benjamin A; Wood-Vasey, W Michael; Yèche, Christophe; York, Donald G

    2013-01-01

    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. The catalog also includes known quasars (mostly from SDSS-I and II) that were reobserved by BOSS. The catalog contains 166,583 quasars (74,454 are new discoveries since SDSS-DR9) detected over 6,373 deg$^{2}$ with robust identification and redshift measured by a combination of principal component eigenspectra. The number of quasars with $z>2.15$ (117,668) is $\\sim$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 (CIV, CIII, MgII). 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-...

  18. Clues to Quasar Broad Line Region Geometry and Kinematics

    DEFF Research Database (Denmark)

    Vestergaard, Marianne; Wilkes, B. J.; Barthel, P. D.

    2000-01-01

    We present evidence that the high-velocity CIV lambda 1549 emission line gas of radio-loud quasars may originate in a disk-like configuration, in close proximity to the accretion disk often assumed to emit the low-ionization lines. For a sample of 36 radio-loud z~2 quasars we find the 20--30% peak...

  19. High-redshift SDSS Quasars with Weak Emission Lines

    DEFF Research Database (Denmark)

    Diamond-Stanic, Aleksandar M.; Fan, Xiaohui; Brandt, W. N.

    2009-01-01

    We identify a sample of 74 high-redshift quasars (z > 3) with weak emission lines from the Fifth Data Release of the Sloan Digital Sky Survey and present infrared, optical, and radio observations of a subsample of four objects at z > 4. These weak emission-line quasars (WLQs) constitute a promine...

  20. Bursty star formation feedback and cooling outflows

    Science.gov (United States)

    Suarez, Teresita; Pontzen, Andrew; Peiris, Hiranya V.; Slyz, Adrianne; Devriendt, Julien

    2016-10-01

    We study how outflows of gas launched from a central galaxy undergoing repeated starbursts propagate through the circum-galactic medium (CGM), using the simulation code RAMSES. We assume that the outflow from the disc can be modelled as a rapidly moving bubble of hot gas at ˜1 kpc above disc, then ask what happens as it moves out further into the halo around the galaxy on ˜100 kpc scales. To do this, we run 60 two-dimensional simulations scanning over parameters of the outflow. Each of these is repeated with and without radiative cooling, assuming a primordial gas composition to give a lower bound on the importance of cooling. In a large fraction of radiative-cooling cases we are able to form rapidly outflowing cool gas from in situ cooling of the flow. We show that the amount of cool gas formed depends strongly on the `burstiness' of energy injection; sharper, stronger bursts typically lead to a larger fraction of cool gas forming in the outflow. The abundance ratio of ions in the CGM may therefore change in response to the detailed historical pattern of star formation. For instance, outflows generated by star formation with short, intense bursts contain up to 60 per cent of their gas mass at temperatures <5 × 104 K; for near-continuous star formation, the figure is ≲5 per cent. Further study of cosmological simulations, and of idealized simulations with e.g. metal-cooling, magnetic fields and/or thermal conduction, will help to understand the precise signature of bursty outflows on observed ion abundances.

  1. Searching for the Physical Drivers of Eigenvector-1 From Quasars to Nano-Quasars

    CERN Document Server

    Marziani, P

    2002-01-01

    We point out an analogy between two accreting white dwarfs with jets (CH Cyg and MWC 560) and powerful quasars. In spite of the enormous difference in the mass of the central object (a factor about 10^7), the emission lines are strikingly similar to those of I Zw1 (the prototype "Narrow Line Seyfert 1" nucleus whose spectrum is widely used as an FeII template for almost all quasars). The spectral similarity give us the unique possibility to consider the optical Eigenvector-1 diagram using objects less massive by a factor of millions. Our results reinforce the interpretation of the "Eigenvector-1 correlations" found for low redshift quasars as driven mainly by the source luminosity to central compact object mass ratio(L/M). The accreting white dwarfs CH Cyg and MWC 560, their jets and emission lines, may well represent the low energy, non relativistic end of the accretion phenomena, which encompass the most powerful quasars and the microquasars. The remarkable similarities suggest that they may be legitimately...

  2. Pressurized groundwater outflow experiments and numerical modeling for outflow channels on Mars

    NARCIS (Netherlands)

    Marra, Wouter A.; Hauber, Ernst; McLelland, Stuart J.; Murphy, Brendan J.; Parsons, Daniel R.; Conway, Susan J.; Roda, Manuel; Govers, Rob; Kleinhans, Maarten G.

    2014-01-01

    The landscape of Mars shows incised channels that often appear abruptly in the landscape, suggesting a groundwater source. However, groundwater outflow processes are unable to explain the reconstructed peak discharges of the largest outflow channels based on their morphology. Therefore, there is a d

  3. Quasar Variability Measurements With SDSS Repeated Imaging and POSS Data

    CERN Document Server

    Ivezic, Z; Juric, M; Anderson, S; Hall, P B; Richards, G T; Rockosi, C M; Vanden Berk, Daniel E; Turner, E L; Knapp, G R; Gunn, J E; Schlegel, D J; Strauss, M A; Schneider, D P

    2004-01-01

    We analyze the properties of quasar variability using repeated SDSS imaging data in five UV-to-far red photometric bands, accurate to 0.02 mag, for 13,000 spectroscopically confirmed quasars. The observed time lags span the range from 3 hours to over 3 years, and constrain the quasar variability for rest-frame time lags of up to two years, and at rest-frame wavelengths from 1000 Ang. to 6000 Ang. We demonstrate that 66,000 SDSS measurements of magnitude differences can be described within the measurement noise by a simple function of only three free parameters. The addition of POSS data constrains the long-term behavior of quasar variability and provides evidence for a turn-over in the structure function. This turn-over indicates that the characteristic time scale for optical variability of quasars is of the order 1 year.

  4. Luminous, High-z, Type-2 Quasars are Still Missing

    Science.gov (United States)

    Richards, Gordon T.; Hennawi, Joseph F.; Rivera, Angelica

    2017-01-01

    A simple unified model suggests that there should be roughly equal numbers of type-1 (unobscured) and type 2 (obscured) quasars. However, we argue that the expected population of luminous, high-z, type-2 quasars are still missing. While large numbers of type-2 AGNs have now been identified (both via spectroscopy and through color-based arguments in the optical, IR, and X-ray), the vast majority of these are low-luminosity objects at zmodel" predict similar numbers of type-1 and type-2 quasars, this conspicuous lack of luminous type-2 quasars at high-redshift constitutes a major unsolved problem. To uncover these missing type-2 quasars, we explore a candidate selection algorithm that utilizes the sky area of AllWISE, the depth/resolution of large-area Spitzer-IRAC surveys, and optical data from the SDSS.

  5. Protostellar Outflows and Radiative Feedback from Massive Stars. II. Feedback, Star Formation Efficiency, and Outflow Broadening

    CERN Document Server

    Kuiper, Rolf; Yorke, Harold W

    2016-01-01

    We perform two-dimensional axially symmetric radiation-hydrodynamic simulations to assess the impact of outflows and radiative force feedback from massive protostars by varying when the protostellar outflow starts, the ratio of ejection to accretion rates, and the strength of the wide angle disk wind component. The star formation efficiency, i.e. the ratio of final stellar mass to initial core mass, is dominated by radiative forces and the ratio of outflow to accretion rates. Increasing this ratio has three effects: First, the protostar grows slower with a lower luminosity at any given time, lowering radiative feedback. Second, bipolar cavities cleared by the outflow are larger, further diminishing radiative feedback on disk and core scales. Third, the higher momentum outflow sweeps up more material from the collapsing envelope, decreasing the protostar's potential mass reservoir via entrainment. The star formation efficiency varies with the ratio of ejection to accretion rates from 50% in the case of very we...

  6. Clustering Analyses of 300,000 Photometrically Classified Quasars--I. Luminosity and Redshift Evolution in Quasar Bias

    CERN Document Server

    Myers, A D; Nichol, R C; Richards, G T; Schneider, D P; Bahcall, N A; Myers, Adam D.; Brunner, Robert J.; Nichol, Robert C.; Richards, Gordon T.; Schneider, Donald P.; Bahcall, Neta A.

    2006-01-01

    Using ~300,000 photometrically classified quasars, by far the largest quasar sample ever used for such analyses, we study the redshift and luminosity evolution of quasar clustering on scales of ~50 kpc/h to ~20 Mpc/h from redshifts of z~0.75 to z~2.28. We parameterize our clustering amplitudes using realistic dark matter models, and find that a LCDM power spectrum provides a superb fit to our data with a redshift-averaged quasar bias of b_Q = 2.41+/-0.08 ($P_{99.6% using our data set alone, increasing to >99.9999% if stellar contamination is not explicitly parameterized. We measure the quasar classification efficiency across our full sample as a = 95.6 +/- ^{4.4}_{1.9}%, a star-quasar separation comparable with the star-galaxy separation in many photometric studies of galaxy clustering. We derive the mean mass of the dark matter halos hosting quasars as MDMH=(5.2+/-0.6)x10^{12} M_solar/h. At z~1.9 we find a $1.5\\sigma$ deviation from luminosity-independent quasar clustering; this suggests that increasing our ...

  7. Quasars Probing Quasars VIII. The Physical Properties of the Cool Circumgalactic medium Surrounding z ~ 2-3 Massive Galaxies

    CERN Document Server

    Lau, Marie Wingyee; Hennawi, Joseph F

    2015-01-01

    We characterize the physical properties of the cool T ~ 10^4 K circumgalactic medium surrounding z ~ 2-3 quasar host galaxies, which are predicted to evolve into present day massive ellipticals. Using a statistical sample of 14 quasar pairs with projected separation 100 cm^-3 and subparsec scale gas clumps.

  8. Cerebral venous outflow and cerebrospinal fluid dynamics

    Directory of Open Access Journals (Sweden)

    Clive B. Beggs

    2014-12-01

    Full Text Available In this review, the impact of restricted cerebral venous outflow on the biomechanics of the intracranial fluid system is investigated. The cerebral venous drainage system is often viewed simply as a series of collecting vessels channeling blood back to the heart. However there is growing evidence that it plays an important role in regulating the intracranial fluid system. In particular, there appears to be a link between increased cerebrospinal fluid (CSF pulsatility in the Aqueduct of Sylvius and constricted venous outflow. Constricted venous outflow also appears to inhibit absorption of CSF into the superior sagittal sinus. The compliance of the cortical bridging veins appears to be critical to the behaviour of the intracranial fluid system, with abnormalities at this location implicated in normal pressure hydrocephalus. The compliance associated with these vessels appears to be functional in nature and dependent on the free egress of blood out of the cranium via the extracranial venous drainage pathways. Because constricted venous outflow appears to be linked with increased aqueductal CSF pulsatility, it suggests that inhibited venous blood outflow may be altering the compliance of the cortical bridging veins.

  9. Evolution of Mass Outflow in Protostars

    CERN Document Server

    Watson, Dan M; Fischer, William J; Forrest, W J; Manoj, P; Megeath, S Thomas; Melnick, Gary J; Najita, Joan; Neufeld, David A; Sheehan, Patrick D; Stutz, Amelia M; Tobin, John J

    2015-01-01

    We have surveyed 84 Class 0, Class I, and flat-spectrum protostars in mid-infrared [Si II], [Fe II] and [S I] line emission, and 11 of these in far-infrared [O I] emission. We use the results to derive their mass outflow rates. Thereby we observe a strong correlation of mass outflow rates with bolometric luminosity, and with the inferred mass accretion rates of the central objects, which continues through the Class 0 range the trend observed in Class II young stellar objects. Along this trend from large to small mass-flow rates, the different classes of young stellar objects lie in the sequence Class 0 -- Class I/flat-spectrum -- Class II, indicating that the trend is an evolutionary sequence in which mass outflow and accretion rates decrease together with increasing age, while maintaining rough proportionality. The survey results include two which are key tests of magnetocentrifugal outflow-acceleration mechanisms: the distribution of the outflow/accretion branching ratio b, and limits on the distribution of...

  10. Bursty star formation feedback and cooling outflows

    CERN Document Server

    Suarez, Teresita; Peiris, Hiranya V; Slyz, Adrianne; Devriendt, Julien

    2016-01-01

    We study how outflows of gas launched from a central galaxy undergoing repeated starbursts propagate through the circumgalactic medium (CGM), using the simulation code RAMSES. We assume that the outflow from the disk can be modelled as a rapidly moving bubble of hot gas at $\\mathrm{\\sim1\\;kpc}$ above disk, then ask what happens as it moves out further into the halo around the galaxy on $\\mathrm{\\sim 100\\;kpc}$ scales. To do this we run 60 two-dimensional simulations scanning over parameters of the outflow. Each of these is repeated with and without radiative cooling, assuming a primordial gas composition to give a lower bound on the importance of cooling. In a large fraction of radiative-cooling cases we are able to form rapidly outflowing cool gas from in situ cooling of the flow. We show that the amount of cool gas formed depends strongly on the 'burstiness' of energy injection; sharper, stronger bursts typically lead to a larger fraction of cool gas forming in the outflow. The abundance ratio of ions in th...

  11. Data mining for gravitationally lensed quasars

    Science.gov (United States)

    Agnello, Adriano; Kelly, Brandon C.; Treu, Tommaso; Marshall, Philip J.

    2015-04-01

    Gravitationally lensed quasars are brighter than their unlensed counterparts and produce images with distinctive morphological signatures. Past searches and target-selection algorithms, in particular the Sloan Quasar Lens Search (SQLS), have relied on basic morphological criteria, which were applied to samples of bright, spectroscopically confirmed quasars. The SQLS techniques are not sufficient for searching into new surveys (e.g. DES, PS1, LSST), because spectroscopic information is not readily available and the large data volume requires higher purity in target/candidate selection. We carry out a systematic exploration of machine-learning techniques and demonstrate that a two-step strategy can be highly effective. In the first step, we use catalogue-level information (griz+WISE magnitudes, second moments) to pre-select targets, using artificial neural networks. The accepted targets are then inspected with pixel-by-pixel pattern recognition algorithms (gradient-boosted trees), to form a final set of candidates. The results from this procedure can be used to further refine the simpler SQLS algorithms, with a twofold (or threefold) gain in purity and the same (or 80 per cent) completeness at target-selection stage, or a purity of 70 per cent and a completeness of 60 per cent after the candidate-selection step. Simpler photometric searches in griz+WISE based on colour cuts would provide samples with 7 per cent purity or less. Our technique is extremely fast, as a list of candidates can be obtained from a Stage III experiment (e.g. DES catalogue/data base) in a few CPU hours. The techniques are easily extendable to Stage IV experiments like LSST with the addition of time domain information.

  12. Parsec-scale radio structures in Quasars

    Science.gov (United States)

    Coldwell, G.; Paragi, Z.; Gurvits, L.

    Very Long Baseline Interferometry (VLBI) con su nueva extensión para el radio telescopio orbital, VSOP/HALCA, ofrece una incomparable resolución angular alcanzando escalas de milisegundos y submilisegundos de arco a longitudes de onda de centímetros. En este trabajo presentamos observaciones y análisis de estructuras en radio, en escalas de parsec, para 3 radio fuentes extragalácticas de la muestra de VSOP Survey y 1 quasar, 1442+101, del proyecto `VSOP High Redshift'.

  13. A new model for quasar absorption clouds

    Energy Technology Data Exchange (ETDEWEB)

    Doroshkevich, A.G. (Academy of Sciences of USSR, Moscow (USSR). Inst. of Applied Mathematics); Muecket, J.P.; Mueller, V. (Academy of Sciences of GDR, Potsdam (German Democratic Republic). Central Inst. for Astrophysics)

    1990-09-15

    A local model for intervening absorption clouds in quasar spectra is discussed. At the boundary of cold clouds in the hot intergalactic gas a non-linear temperature profile results from electron heat conductivity and radiative energy losses both depending on ionization rates. This transition region causes the excitation of a wide range of ionization levels in the heavy elements of the gas. The predicted column densities along the line-of-sight are comparable with data from identified metal absorption systems at high redshifts. (author).

  14. Discovery of a 2 Kpc Binary Quasar

    OpenAIRE

    Shields, G. A.; Junkkarinen, V.; Beaver, E. A.; Burbidge, E. M.; Cohen, R. D.; Hamann, F.; Lyons, R. W.

    2001-01-01

    LBQS 0103$-$2753 is a binary quasar with a separation of only 0.3 arcsec. The projected spacing of 2.3 kpc at the distance of the source (z = 0.848) is much smaller than that of any other known binary QSO. The binary nature is demonstrated by the very different spectra of the two components and the low probability of a chance pairing. LBQS 0103$-$2753 presumably is a galaxy merger with a small physical separation between the two supermassive black holes. Such objects may provide important con...

  15. Observations of Protostellar Outflow Feedback in Clustered Star Formation

    CERN Document Server

    Nakamura, Fumitaka

    2015-01-01

    We discuss the role of protostellar outflow feedback in clustered star formation using the observational data of recent molecular outflow surveys toward nearby cluster-forming clumps. We found that for almost all clumps, the outflow momentum injection rate is significantly larger than the turbulence dissipation rate. Therefore, the outflow feedback is likely to maintain supersonic turbulence in the clumps. For less massive clumps such as B59, L1551, and L1641N, the outflow kinetic energy is comparable to the clump gravitational energy. In such clumps, the outflow feedback probably affects significantly the clump dynamics. On the other hand, for clumps with masses larger than about 200 M$_\\odot$, the outflow kinetic energy is significantly smaller than the clump gravitational energy. Since the majority of stars form in such clumps, we conclude that outflow feedback cannot destroy the whole parent clump. These characteristics of the outflow feedback support the scenario of slow star formation.

  16. Magnetospheric outflows in young stellar objects

    Directory of Open Access Journals (Sweden)

    Zanni Claudio

    2014-01-01

    Full Text Available Different classes of outflows are associated with the magnetospheric activity of accreting T Tauri protostars. Stellar winds are accelerated along the open field lines anchored in the stellar surface; disk winds (extended or X-type can be launched along the open magnetic surfaces threading the accretion disk; another type of ejection can arise from the region of interaction of the closed magnetosphere with the accretion disk (magnetospheric ejections, conical winds, where the magnetic surfaces undergo quasiperiodic episodes of inflation and reconnection. In this chapter I will present the main dynamical properties of these different types of outflow. Two main issues will be addressed. First, I will try to understand if these ejection phenomena can account for the origin of the jets often observed in young forming stellar systems. Second, I will evaluate the impact of these outflows on the angular momentum evolution of the central protostar.

  17. A Chandra HETG Observation of the Quasar H 1821+643 and Its Surrounding Cluster

    CERN Document Server

    Fang, T; Lee, J C; Marshall, H L; Bryan, G L; Canizares, C R

    2001-01-01

    We present the high-resolution X-ray spectrum of the low-redshift quasar H 1821+643 and its surrounding hot cluster observed with the Chandra High Energy Transmission Grating Spectrometer (HETGS). An iron emission line attributed to the quasar at ~6.43 keV (rest frame) is clearly resolved, with an equivalent width of ~100 eV. Although we cannot rule out contributions to the line from a putative torus, the diskline model provides an acceptable fit to this iron line. We also detect a weak emission feature at ~6.9 keV (rest frame). We suggest that both lines could originate in an accretion disk comprised of a highly ionized optically thin atmosphere sitting atop a mostly neutral disk. We search for absorption features from a warm/hot component of the intergalactic medium along the ~1.5Gpc/h line of sight to the quasar. No absorption features are detected at or above the 3 sigma level while a total of six OVI intervening absorption systems have been detected with HST and FUSE. Based on the lack of OVII and OVIII ...

  18. Simple stellar population modelling of low S/N galaxy spectra and quasar host galaxy applications

    Science.gov (United States)

    Mosby, G.; Tremonti, C. A.; Hooper, E. J.; Wolf, M. J.; Sheinis, A. I.; Richards, J. W.

    2015-02-01

    To study the effect of supermassive black holes (SMBHs) on their host galaxies it is important to study the hosts when the SMBH is near its peak activity. A method to investigate the host galaxies of high luminosity quasars is to obtain optical spectra at positions offset from the nucleus where the relative contribution of the quasar and host is comparable. However, at these extended radii the galaxy surface brightness is often low (20-22 mag arcsec-2) and the resulting spectrum might have such low signal-to-noise ratio (S/N) that it hinders analysis with standard stellar population modelling techniques. To address this problem, we have developed a method that can recover galaxy star formation histories (SFHs) from rest-frame optical spectra with S/N ˜ 5 Å-1. This method uses the statistical technique diffusion k-means to tailor the stellar population modelling basis set. Our diffusion k-means minimal basis set, composed of four broad age bins, is successful in recovering a range of galaxy SFHs. Additionally, using an analytic prescription for seeing conditions, we are able to simultaneously model scattered quasar light and the SFH of quasar host galaxies (QHGs). We use synthetic data to compare results of our novel method with previous techniques. We also present the modelling results on a previously published QHG and show that galaxy properties recovered from a diffusion k-means basis set are less sensitive to noise added to this QHG spectrum. Our new method has a clear advantage in recovering information from QHGs and could also be applied to the analysis of other low S/N galaxy spectra such as those typically obtained for high redshift objects or integral field spectroscopic surveys.

  19. Witnessing the Birth of a Quasar

    CERN Document Server

    Tanaka, Takamitsu; Menou, Kristen

    2010-01-01

    The coalescence of a supermassive black hole binary (SMBHB) is thought to be accompanied by an electromagnetic (EM) afterglow, produced by the viscous infall of the surrounding circumbinary gas disk after the merger. It has been proposed that once the merger has been detected in gravitational waves (GWs) by LISA, follow-up EM searches for this afterglow can help identify the EM counterpart of the LISA source. Here we study whether the afterglows may be sufficiently bright and numerous to be detectable in EM surveys alone. The viscous afterglow, which lasts for years to decades for SMBHBs in LISA's sensitivity window, is characterized by rapid increases in both the bolometric luminosity and in the spectral hardness of the source. If quasar activity is triggered by the same major galaxy mergers that produce SMBHBs, then the afterglow could be interpreted as a signature of the birth of a quasar. Using an idealized model for the post-merger viscous spreading of the circumbinary disk and the resulting light curve,...

  20. Comparing different indicators of quasar orientation

    CERN Document Server

    Van Gorkom, Kyle J; Rauch, Andreas P; Gobeille, Doug B

    2015-01-01

    Radio core dominance, the rest-frame ratio of core to lobe luminosity, has been widely used as a measure of Doppler boosting of a quasar's radio jets and hence of the inclination of the central engine's spin axis to the line of sight. However, the use of the radio lobe luminosity in the denominator (essentially to try and factor out the intrinsic power of the central engine) has been criticized and other proxies for the intrinsic engine power have been proposed. These include the optical continuum luminosity, and the luminosity of the narrow-line region. Each is plausible, but so far none has been shown to be clearly better than the others. In this paper we evaluate four different measures of core dominance using a new sample of 126 radio loud quasars, carefully selected to be as free as possible of orientation bias, together with high quality VLA images and optical spectra from the SDSS. We find that normalizing the radio core luminosity by the optical continuum luminosity yields a demonstrably superior orie...

  1. Quantitative Interpretation of Quasar Microlensing Light Curves

    CERN Document Server

    Kochanek, C S

    2004-01-01

    We develop a general method for analyzing the light curves of microlensed quasars and apply it to the OGLE light curves of the four-image lens Q2237+0305. We simultaneously estimate the effective source velocity, the average stellar mass, the stellar mass function, and the size and structure of the quasar accretion disk. The light curves imply an effective source plane velocity of 10200 km/s ) =0.037h^2 solar masses (0.0059h^2 /Msun < 0.20h^2). We were unable to distinguish a Salpeter mass function from one in which all stars had the same mass, but we do find a strong lower bound of 50% on the fraction of the surface mass density represented by the microlenses. Our models favor a standard thin accretion disk model as the source structure over a simple Gaussian source. For a face-on, thin disk radiating as a black body with temperature profile T_s ~ R^(-3/4), the radius r_s where the temperature matches the filter pass band (2000 Angstroms or T_s(r_s)=70000K) is (1.4 x 10^15)/h cm < r_s < (4.5 x 10^15...

  2. The nuclear to host galaxy relation of high redshift quasars

    CERN Document Server

    Kotilainen, J K; Labita, M; Treves, A; Uslenghi, M

    2007-01-01

    We present near-infrared imaging with ESO VLT+ISAAC of the host galaxies of low luminosity quasars in the redshift range 1 < z < 2, aimed at investigating the relationship between the nuclear and host galaxy luminosities at high redshift. This work complements our previous study to trace the cosmological evolution of the host galaxies of high luminosity quasars (Falomo et al. 2004). The new sample includes 15 low luminosity quasars, nine radio-loud (RLQ) and six radio-quiet (RQQ). They have similar distribution of redshift and optical luminosity, and together with the high luminosity quasars they cover a large range (~4 mag) of the quasar luminosity function. The host galaxies of both types of quasars are in the range of massive inactive ellipticals between L* and 10 L*. RLQ hosts are systematically more luminous than RQQ hosts by a factor of ~2. This difference is similar to that found for the high luminosity quasars. This luminosity gap appears to be independent of the rest-frame U-band luminosity but...

  3. Measuring Quasar Variability with Pan-STARRS1 and SDSS

    CERN Document Server

    Morganson, E; Chambers, K C; Green, P J; Kaiser, N; Magnier, E A; Marshall, P J; Morgan, J S; Price, P A; Rix, H -W; Chlafly, E F S; Tonry, J L; Walter, F

    2014-01-01

    We measure quasar variability using the Panoramic Survey Telescope and Rapid Response System 1 Survey (Pan-STARRS1 or PS1) and the Sloan Digital Sky Survey (SDSS) and establish a method of selecting quasars via their variability in 10,000 square degree surveys. We use 100,000 spectroscopically confirmed quasars that have been well measured in both PS1 and SDSS and take advantage of the decadal time scales that separate SDSS measurements and PS1 measurements. A power law model fits the data well over the entire time range tested, 0.01 to 10 years. Variability in the current PS1-SDSS dataset can efficiently distinguish between quasars and non-varying objects. It improves the purity of a griz quasar color cut from 4.1% to 48% while maintaining 67% completeness. Variability will be very effective at finding quasars in datasets with no u band and in redshift ranges where exclusively photometric selection is not efficient. We show that quasars' rest-frame ensemble variability, measured as a root mean squared in del...

  4. The First High Redshift Quasar from Pan-STARRS

    CERN Document Server

    Morganson, Eric; Decarli, Roberto; Walter, Fabian; Chambers, Ken; McGreer, Ian; Fan, Xiaohui; Burgett, William; Flewelling, Heather; Hodapp, Klaus; Kaiser, Nick; Magnier, Eugene; Price, Paul; Rix, Hans-Walter; Sweeney, Bill; Waters, Christopher

    2011-01-01

    We present the discovery of the first high redshift (z > 5.7) quasar from the Panoramic Survey Telescope and Rapid Response System 1 (Pan-STARRS1 or PS1). This quasar was initially detected as an i dropoutout in PS1, confirmed photometrically with the SAO Widefield InfraRed Camera (SWIRC) at Arizona's Multiple Mirror Telescope (MMT) and the Gamma-Ray Burst Optical/Near-Infrared Detector (GROND) at the MPG 2.2 m telescope in La Silla. The quasar was verified spectroscopically with the the MMT Spectrograph, Red Channel and the Cassegrain Twin Spectrograph (TWIN) at the Calar Alto 3.5 m telescope. It has a redshift of 5.73, an AB z magnitude of 19.4, a luminosity of 3.8 x 10^47 erg/s and a black hole mass of 6.9 x 10^9 solar masses. It is a Broad Absorption Line quasar with a prominent Ly-beta peak and a very blue continuum spectrum. This quasar is the first result from the PS1 high redshift quasar search that is projected to discover more than a hundred i dropout quasars, and could potentially find more than 10...

  5. Similarity of ionized gas nebulae around unobscured and obscured quasars

    CERN Document Server

    Liu, Guilin; Greene, Jenny E

    2014-01-01

    Quasar feedback is suspected to play a key role in the evolution of massive galaxies, by removing or reheating gas in quasar host galaxies and thus limiting the amount of star formation. In this paper we continue our investigation of quasar-driven winds on galaxy-wide scales. We conduct Gemini Integral Field Unit spectroscopy of a sample of luminous unobscured (type 1) quasars, to determine the morphology and kinematics of ionized gas around these objects, predominantly via observations of the [O III]5007 emission line. We find that ionized gas nebulae extend out to ~13 kpc from the quasar, that they are smooth and round, and that their kinematics are inconsistent with gas in dynamical equilibrium with the host galaxy. The observed morphological and kinematic properties are strikingly similar to those of ionized gas around obscured (type 2) quasars with matched [O III] luminosity, with marginal evidence that nebulae around unobscured quasars are slightly more compact. Therefore in samples of obscured and unob...

  6. Distributions of Quasar Hosts on the Galaxy Main Sequence Plane

    Science.gov (United States)

    Zhang, Zhoujian; Shi, Yong; Rieke, George H.; Xia, Xiaoyang; Wang, Yikang; Sun, Bingqing; Wan, Linfeng

    2016-03-01

    The relation between star formation rates (SFRs) and stellar masses, i.e., the galaxy main sequence, is a useful diagnostic of galaxy evolution. We present the distributions relative to the main sequence of 55 optically selected PG and 12 near-IR-selected Two Micron All Sky Survey (2MASS) quasars at z ≤ 0.5. We estimate the quasar host stellar masses from Hubble Space Telescope or ground-based AO photometry, and the SFRs through the mid-infrared aromatic features and far-IR photometry. We find that PG quasar hosts more or less follow the main sequence defined by normal star-forming galaxies while 2MASS quasar hosts lie systematically above the main sequence. PG and 2MASS quasars with higher nuclear luminosities seem to have higher specific SFRs (sSFRs), although there is a large scatter. No trends are seen between sSFRs and SMBH masses, Eddington ratios, or even morphology types (ellipticals, spirals, and mergers). Our results could be placed in an evolutionary scenario with quasars emerging during the transition from ULIRGs/mergers to ellipticals. However, combined with results at higher redshift, they suggest that quasars can be widely triggered in normal galaxies as long as they contain abundant gas and have ongoing star formation.

  7. Imprints of the super-Eddington accretion on the quasar clustering

    Science.gov (United States)

    Oogi, Taira; Enoki, Motohiro; Ishiyama, Tomoaki; Kobayashi, Masakazu A. R.; Makiya, Ryu; Nagashima, Masahiro; Okamoto, Takashi; Shirakata, Hikari

    2017-10-01

    Super-Eddington mass accretion has been suggested as an efficient mechanism to grow supermassive black holes (SMBHs). We investigate the imprint left by the radiative efficiency of the super-Eddington accretion process on the clustering of quasars using a new semi-analytic model of galaxy and quasar formation based on large-volume cosmological $N$-body simulations. Our model includes a simple model for the radiative efficiency of a quasar, which imitates the effect of photon trapping for a high mass accretion rate. We find that the model of radiative efficiency affects the relation between the quasar luminosity and the quasar host halo mass. The quasar host halo mass has only weak dependence on quasar luminosity when there is no upper limit for quasar luminosity. On the other hand, it has significant dependence on quasar luminosity when the quasar luminosity is limited by its Eddington luminosity. In the latter case, the quasar bias also depends on the quasar luminosity, and the quasar bias of bright quasars is in agreement with observations. Our results suggest that the quasar clustering studies can provide a constraint on the accretion disc model.

  8. Quasar UV luminosity function evolution up to z = 8

    Science.gov (United States)

    Manti, S.; Gallerani, S.; Ferrara, A.; Greig, B.; Feruglio, C.

    2017-04-01

    We study the redshift evolution of the quasar (QSO) UV luminosity function (LF) for 0.5 up to date observational data and, in particular, the recently discovered population of faint active galactic nuclei (AGNs). We fit the QSO LF using either a double power-law function or a Schechter function, finding that both forms provide good fits to the data. We derive empirical relations for the LF parameters as a function of redshift and, based on these results, predict the QSO UV LF at z = 8. From the inferred LF evolution, we compute the redshift evolution of the QSO/AGN comoving ionizing emissivity and hydrogen photoionization rate. If faint AGNs are included, the contribution of QSOs to reionization increases substantially. However, their level of contribution critically depends on the detailed shape of the QSO LF, which can be constrained by efficient searches of high-z QSOs. To this aim, we predict the expected (i) number of z > 6 QSOs detectable by ongoing and future near-infrared surveys (as EUCLID and Wide-Field Infrared Survey Telescope), and (ii) number counts for a single radio-recombination line observation with Square Kilometre Array-MID (FoV = 0.49 deg2) as a function of the Hnα flux density, at 0 < z < 8. These surveys (even at z < 6) will be fundamental to better constrain the role of QSOs as reionization sources.

  9. Understanding the IGM Through the Use of a Lensed Quasar

    Science.gov (United States)

    Panurach, Teresa; O'Dowd, Matthew

    2017-01-01

    Quasars are among the brightest objects in the universe. In rare gravitationally lensed quasars, their light is split and travels along multiple paths through an intervening lensing galaxy. The light that follows these different paths encounters various parts of the intergalactic medium (IGM) and may show different absorption features, indicating the varying composition of the IGM. By analyzing spectra from a gravitationally lensed quasar, B1422+231, observed by the Gemini North Telescope, we compare the absorption features identified in the lensed images to form a small-scale structure of the IGM.

  10. How do optically-similar quasars look elsewhere?

    Science.gov (United States)

    Shang, Zhaohui; Ma, Bin; Brotherton, Michael S.

    2016-06-01

    As too many spectroscopic and physical parameters complicates the study of quasars, reducing the number of parameters can help to isolate many problems in general. Using spectral principal component analysis, we selected from SDSS a pilot sample of quasars with virtually identical spectral features in H-beta region. We found that they also show very similar spectral features outside the H-beta region in the optical band. We also explore their properties in other available wavelength bands and plan to study the accretion, ionization, and possibly geometry of quasars using this controlled sample.

  11. Black Hole Mass Estimates of Radio Selected Quasars

    OpenAIRE

    Oshlack, Alicia; Webster, Rachel; Whiting, Matthew

    2002-01-01

    The black hole (BH) mass in the centre of AGN has been estimated for a sample of radio-selected flat-spectrum quasars to investigate the relationship between BH mass and radio properties of quasars. We have used the virial assumption with measurements of the H$\\beta$ FWHM and luminosity to estimate the central BH mass. In contrast to previous studies we find no correlation between BH mass and radio power in these AGN. We find a range in BH mass similar to that seen in radio-quiet quasars from...

  12. The Sloan Digital Sky Survey Quasar Catalog: Twelfth data release

    Science.gov (United States)

    Pâris, Isabelle; Petitjean, Patrick; Ross, Nicholas P.; Myers, Adam D.; Aubourg, Éric; Streblyanska, Alina; Bailey, Stephen; Armengaud, Éric; Palanque-Delabrouille, Nathalie; Yèche, Christophe; Hamann, Fred; Strauss, Michael A.; Albareti, Franco D.; Bovy, Jo; Bizyaev, Dmitry; Niel Brandt, W.; Brusa, Marcella; Buchner, Johannes; Comparat, Johan; Croft, Rupert A. C.; Dwelly, Tom; Fan, Xiaohui; Font-Ribera, Andreu; Ge, Jian; Georgakakis, Antonis; Hall, Patrick B.; Jiang, Linhua; Kinemuchi, Karen; Malanushenko, Elena; Malanushenko, Viktor; McMahon, Richard G.; Menzel, Marie-Luise; Merloni, Andrea; Nandra, Kirpal; Noterdaeme, Pasquier; Oravetz, Daniel; Pan, Kaike; Pieri, Matthew M.; Prada, Francisco; Salvato, Mara; Schlegel, David J.; Schneider, Donald P.; Simmons, Audrey; Viel, Matteo; Weinberg, David H.; Zhu, Liu

    2017-01-01

    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] half maximum (FWHM) larger than 500 km s-1 or, if not, have interesting/complex absorption features. The catalog also includes previously known quasars (mostly from SDSS-I and II) that were reobserved by BOSS. The catalog contains 297 301 quasars (272 026 are new discoveries since the beginning of SDSS-III) detected over 9376 deg2 with robust identification and redshift measured by a combination of principal component eigenspectra. The number of quasars with z > 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

  13. BLOWIN' IN THE WIND: BOTH ''NEGATIVE'' AND ''POSITIVE'' FEEDBACK IN AN OBSCURED HIGH-z QUASAR

    Energy Technology Data Exchange (ETDEWEB)

    Cresci, G.; Mannucci, F. [INAF-Osservatorio Astrofisco di Arcetri, largo E. Fermi 5, I-50127, Firenze (Italy); Mainieri, V. [European Southern Observatory, Karl-Schwarzschild-strasse 2, D-85748 Garching bei München (Germany); Brusa, M.; Perna, M.; Lanzuisi, G. [Dipartimento di Fisica e Astronomia, Università di Bologna, viale Berti Pichat 6/2, I-40127 Bologna (Italy); Marconi, A. [Dipartimento di Fisica e Astronomia, Università degli Studi di Firenze, via G. Sansone 1, I-50019 Sesto F.no, Firenze (Italy); Piconcelli, E.; Feruglio, C.; Fiore, F.; Bongiorno, A. [INAF-Osservatorio Astronomico di Roma, via Frascati 33, I-00040 Monteporzio Catone (Italy); Maiolino, R. [Cavendish Laboratory, University of Cambridge, 19 J. J. Thomson Avenue, Cambridge (United Kingdom); Merloni, A [Max Planck Institut für Extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching bei München (Germany); Schramm, M.; Silverman, J. D. [Kavli Institute for the Physics and Mathematics of the Universe (WPI), Todai Institutes for Advanced Study, the University of Tokyo, Kashiwanoha 5-1-5, Kashiwa-shi, Chiba 277-8568 (Japan); Civano, F., E-mail: gcresci@arcetri.astro.it [Department of Physics and Yale Center for Astronomy and Astrophysics, Yale University, PO Box 208121, New Haven, CT 06520-8121 (United States)

    2015-01-20

    Quasar feedback in the form of powerful outflows is invoked as a key mechanism to quench star formation in galaxies, preventing massive galaxies to overgrow and producing the red colors of ellipticals. On the other hand, some models are also requiring ''positive'' active galactic nucleus feedback, inducing star formation in the host galaxy through enhanced gas pressure in the interstellar medium. However, finding observational evidence of the effects of both types of feedback is still one of the main challenges of extragalactic astronomy, as few observations of energetic and extended radiatively driven winds are available. Here we present SINFONI near infrared integral field spectroscopy of XID2028, an obscured, radio-quiet z = 1.59 QSO detected in the XMM-COSMOS survey, in which we clearly resolve a fast (1500 km s{sup –1}) and extended (up to 13 kpc from the black hole) outflow in the [O III] lines emitting gas, whose large velocity and outflow rate are not sustainable by star formation only. The narrow component of Hα emission and the rest frame U-band flux from Hubble Space Telescope/Advanced Camera for Surveys imaging enable to map the current star formation in the host galaxy: both tracers independently show that the outflow position lies in the center of an empty cavity surrounded by star forming regions on its edge. The outflow is therefore removing the gas from the host galaxy (''negative feedback''), but also triggering star formation by outflow induced pressure at the edges (''positive feedback''). XID2028 represents the first example of a host galaxy showing both types of feedback simultaneously at work.

  14. Production of the entire range of r-process nuclides by black hole accretion disc outflows from neutron star mergers

    Science.gov (United States)

    Wu, Meng-Ru; Fernández, Rodrigo; Martínez-Pinedo, Gabriel; Metzger, Brian D.

    2016-12-01

    We consider r-process nucleosynthesis in outflows from black hole accretion discs formed in double neutron star and neutron star-black hole mergers. These outflows, powered by angular momentum transport processes and nuclear recombination, represent an important - and in some cases dominant - contribution to the total mass ejected by the merger. Here we calculate the nucleosynthesis yields from disc outflows using thermodynamic trajectories from hydrodynamic simulations, coupled to a nuclear reaction network. We find that outflows produce a robust abundance pattern around the second r-process peak (mass number A ˜ 130), independent of model parameters, with significant production of A dynamical ejecta with high electron fraction may not be required to explain the observed abundances of r-process elements in metal poor stars. Disc outflows reach the third peak (A ˜ 195) in most of our simulations, although the amounts produced depend sensitively on the disc viscosity, initial mass or entropy of the torus, and nuclear physics inputs. Some of our models produce an abundance spike at A = 132 that is absent in the Solar system r-process distribution. The spike arises from convection in the disc and depends on the treatment of nuclear heating in the simulations. We conclude that disc outflows provide an important - and perhaps dominant - contribution to the r-process yields of compact binary mergers, and hence must be included when assessing the contribution of these systems to the inventory of r-process elements in the Galaxy.

  15. A survey of z > 5.7 quasars in the sloan digital sky survey. 4. discovery of seven additional quasars

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Xiao-Hui; Strauss, Michael A.; Richards, Gordon T.; Hennawi, Joseph F.; Becker, Robert H.; White, Richard L.; Diamond-Stanic, Aleksandar M.; onley, Jennifer L.D; Jiang, Lin-Hua; Kim, J.Serena; Vestergaard, Marianne; Young, Jason E.; Gunn, James E.; Lupton, Robert H.; Knapp, Gillian R.; Schneider, Donald P.; Brandt, W.N.; Bahcall, Neta A.; Barentine, J.C.; Brinkmann, J.; Brewington, Howard J.; /Arizona U., Astron. Dept. - Steward Observ. /Princeton U. Observ. /Johns Hopkins U. /UC, Berkeley, Astron. Dept. /UC, Davis

    2005-12-01

    We present the discovery of seven quasars at z > 5.7, selected from {approx}2000 deg{sup 2} of multicolor imaging data of the Sloan Digital Sky Survey (SDSS). The new quasars have redshifts z from 5.79 to 6.13. Five are selected as part of a complete flux-limited sample in the SDSS Northern Galactic Cap; two have larger photometric errors and are not part of the complete sample. One of the new quasars, SDSS J1335+3533 (z = 5.93), exhibits no emission lines; the 3-{sigma} limit on the rest-frame equivalent width of Ly{alpha} + NV line is 5 {angstrom}. It is the highest redshift lineless quasar known, and could be a gravitational lensed galaxy, a BL Lac object or a new type of quasar. Two new z > 6 quasars, SDSS 1250+3130 (z = 6.13) and SDSS J1137+3549 (z = 6.01), show deep Gunn-Peterson absorption gaps in Ly{alpha}. These gaps are narrower the complete Gunn-Peterson absorption troughs observed among quasars at z > 6.2 and do not have complete Ly{beta} absorption.

  16. Protostellar Outflow Evolution in Turbulent Environments

    Energy Technology Data Exchange (ETDEWEB)

    Cunningham, A; Frank, A; Carroll, J; Blackman, E; Quillen, A

    2008-04-11

    The link between turbulence in star formatting environments and protostellar jets remains controversial. To explore issues of turbulence and fossil cavities driven by young stellar outflows we present a series of numerical simulations tracking the evolution of transient protostellar jets driven into a turbulent medium. Our simulations show both the effect of turbulence on outflow structures and, conversely, the effect of outflows on the ambient turbulence. We demonstrate how turbulence will lead to strong modifications in jet morphology. More importantly, we demonstrate that individual transient outflows have the capacity to re-energize decaying turbulence. Our simulations support a scenario in which the directed energy/momentum associated with cavities is randomized as the cavities are disrupted by dynamical instabilities seeded by the ambient turbulence. Consideration of the energy power spectra of the simulations reveals that the disruption of the cavities powers an energy cascade consistent with Burgers-type turbulence and produces a driving scale-length associated with the cavity propagation length. We conclude that fossil cavities interacting either with a turbulent medium or with other cavities have the capacity to sustain or create turbulent flows in star forming environments. In the last section we contrast our work and its conclusions with previous studies which claim that jets can not be the source of turbulence.

  17. Accretion, Outflows, and Winds of Magnetized Stars

    CERN Document Server

    Romanova, M M

    2016-01-01

    Many types of stars have strong magnetic fields that can dynamically influence the flow of circumstellar matter. In stars with accretion disks, the stellar magnetic field can truncate the inner disk and determine the paths that matter can take to flow onto the star. These paths are different in stars with different magnetospheres and periods of rotation. External field lines of the magnetosphere may inflate and produce favorable conditions for outflows from the disk-magnetosphere boundary. Outflows can be particularly strong in the propeller regime, wherein a star rotates more rapidly than the inner disk. Outflows may also form at the disk-magnetosphere boundary of slowly rotating stars, if the magnetosphere is compressed by the accreting matter. In isolated, strongly magnetized stars, the magnetic field can influence formation and/or propagation of stellar wind outflows. Winds from low-mass, solar-type stars may be either thermally or magnetically driven, while winds from massive, luminous O and B type stars...

  18. The Resolved Outflow from 3C 48

    Science.gov (United States)

    Shih, Hsin-Yi; Stockton, Alan

    2014-10-01

    We investigate the properties of the high-velocity outflow driven by the young radio jet of 3C 48, a compact-steep-spectrum source. We use the Space Telescope Imaging Spectrograph on board the Hubble Space Telecope to obtain (1) low-resolution UV and optical spectra and (2) multi-slit medium-resolution spectra of the ionized outflow. With supporting data from ground-based spectrographs, we are able to accurately measure the ratios of diagnostic emission lines such as [O III] λ5007, [O III] λ3727, [N II] λ6548, Hα, Hβ, [Ne V] λ3425, and [Ne III] λ3869. We fit the observed emission-line ratios using a range of ionization models, powered by active galactic nucleus (AGN) radiation and shocks, produced by the MAPPINGS code. We have determined that AGN radiation is likely the dominant ionization source. The outflow's density is estimated to be in the range n = 103-104 cm-3, the mass is ~6 × 106 M ⊙, and the metallicity is likely equal to or higher than solar. Compared with the typical outflows associated with more evolved radio jets, this young outflow is denser, less massive, and more metal rich. Multi-slit observations allow us to construct a two-dimensional velocity map of the outflow that shows a wide range of velocities with distinct velocity components, suggesting a wide-angle clumpy outflow. Based in part on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program GO-11574. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. Some of the

  19. Outflow Entrainment and Feedback: A Case Study with HH46/47 Molecular Outflow

    Science.gov (United States)

    Zhang, Yichen; Arce, H.; Mardones, D.; Cabrit, S.

    2017-06-01

    Our ALMA multi-cycle multi-band observations of HH46/47 outflow show co-existence of entrainment by both wide-angle wind and jet bow-shock and this outflow is at a moment that the former has just become dominant. The estimated outflow mass and strength suggest that it has already strongly affected the core-to-star efficiency to 1/3 at this early stage. The zoom-in observation also reveals multiple wide outflowing shells with positions and shapes smoothly changing over a wide range of velocity, which may be an evidence of episodic eruption not only in jet but also in the wide-angle wind.

  20. Herschel reveals a molecular outflow in a z = 2.3 ULIRG

    CERN Document Server

    George, Richard; Smail, Ian; Swinbank, Mark; Hopwood, Rosalind; Stanley, Fiona; Swinyard, Bruce; Valtchanov, Ivan; van der Werf, Paul

    2014-01-01

    We report the results from a 19-hr integration with the SPIRE Fourier Transform Spectrometer aboard the Herschel Space Observatory which has revealed the presence of a molecular outflow from the Cosmic Eyelash (SMM J2135-0102, hereafter SMMJ2135) via the detection of blueshifted OH absorption. Detections of several fine-structure emission lines indicate low-excitation HII regions contribute strongly to the [CII] luminosity in this z = 2.3 ULIRG. The OH feature suggests a maximum wind velocity of 700 km/s and outflow rate of ~60 Msun/yr. This is lower than the expected escape velocity of the host dark matter halo, ~1000 km/s. A large fraction of the available molecular gas could thus be converted into stars via a burst protracted by the resulting gas fountain, until an AGN-driven outflow can eject the remaining gas.

  1. The Implications of Extreme Outflows from Extreme Starbursts

    OpenAIRE

    Heckman, Timothy M.; Borthakur, Sanchayeeta

    2016-01-01

    Interstellar ultraviolet absorption-lines provide crucial information about the properties of galactic outflows. In this paper, we augment our previous analysis of the systematic properties of starburst-driven galactic outflows by expanding our sample to include a rare population of starbursts with exceptionally high outflow velocities. In principle, these could be a qualitatively different phenomenon from more typical outflows. However, we find that instead these starbursts lie on, or along ...

  2. Evidence for ultrafast outflows in radio-quiet AGNs - III. Location and energetics

    Science.gov (United States)

    Tombesi, F.; Cappi, M.; Reeves, J. N.; Braito, V.

    2012-05-01

    Using the results of a previous X-ray photoionization modelling of blueshifted Fe K absorption lines on a sample of 42 local radio-quiet AGNs observed with XMM-Newton, in this Letter we estimate the location and energetics of the associated ultrafast outflows (UFOs). Due to significant uncertainties, we are essentially able to place only lower/upper limits. On average, their location is in the interval ˜0.0003-0.03 pc (˜ 102-104rs) from the central black hole, consistent with what is expected for accretion disc winds/outflows. The mass outflow rates are constrained between ˜0.01 and 1 M⊙ yr-1, corresponding to >rsim5-10 per cent of the accretion rates. The average lower/upper limits on the mechanical power are log? 42.6-44.6 erg s-1. However, the minimum possible value of the ratio between the mechanical power and bolometric luminosity is constrained to be comparable or higher than the minimum required by simulations of feedback induced by winds/outflows. Therefore, this work demonstrates that UFOs are indeed capable to provide a significant contribution to the AGN cosmological feedback, in agreement with theoretical expectations and the recent observation of interactions between AGN outflows and the interstellar medium in several Seyfert galaxies.

  3. Evidence for Ultra-Fast Outflows in Radio-Quiet AGNs: III - Location and Energetics

    Science.gov (United States)

    Tombesi, F.; Cappi, M.; Reeves, J. N.; Braito, V.

    2012-01-01

    Using the results of a previous X-ray photo-ionization modelling of blue-shifted Fe K absorption lines on a sample of 42 local radio-quiet AGNs observed with XMM-Newton, in this letter we estimate the location and energetics of the associated ultrafast outflows (UFOs). Due to significant uncertainties, we are essentially able to place only lower/upper limits. On average, their location is in the interval approx.0.0003-0.03pc (approx.10(exp 2)-10(exp 4)tau(sub s) from the central black hole, consistent with what is expected for accretion disk winds/outflows. The mass outflow rates are constrained between approx.0.01- 1 Stellar Mass/y, corresponding to approx. or >5-10% of the accretion rates. The average lower-upper limits on the mechanical power are logE(sub K) approx. or = 42.6-44.6 erg/s. However, the minimum possible value of the ratio between the mechanical power and bolometric luminosity is constrained to be comparable or higher than the minimum required by simulations of feedback induced by winds/outflows. Therefore, this work demonstrates that UFOs are indeed capable to provide a significant contribution to the AGN r.osmological feedback, in agreement with theoretical expectations and the recent observation of interactions between AGN outflows and the interstellar medium in several Seyferts galaxies .

  4. The Hunt for Red Quasars: Luminous Obscured Black Hole Growth Unveiled in the Stripe 82 X-Ray Survey

    Science.gov (United States)

    LaMassa, Stephanie M.; Glikman, Eilat; Brusa, Marcella; Rigby, Jane R.; Tasnim Ananna, Tonima; Stern, Daniel; Lira, Paulina; Urry, C. Megan; Salvato, Mara; Alexandroff, Rachael; Allevato, Viola; Cardamone, Carolin; Civano, Francesca; Coppi, Paolo; Farrah, Duncan; Komossa, S.; Lanzuisi, Giorgio; Marchesi, Stefano; Richards, Gordon; Trakhtenbrot, Benny; Treister, Ezequiel

    2017-10-01

    We present results of a ground-based near-infrared campaign with Palomar TripleSpec, Keck NIRSPEC, and Gemini GNIRS to target two samples of reddened active galactic nucleus (AGN) candidates from the 31 deg2 Stripe 82 X-ray survey. One sample, which is ∼89% complete to K 4, Vega). The fainter sample (K> 17, Vega) represents a pilot program to follow-up four sources from a parent sample of 34 that are not detected in the single-epoch SDSS catalog and have WISE quasar colors. All 12 sources are broad-line AGNs (at least one permitted emission line has an FWHM exceeding 1300 km s‑1) and span a redshift range 0.59 0.5), and a greater percentage have high X-ray luminosities ({L}{{X},{full}}> {10}44 erg s‑1). Such outflows and high luminosities may be consistent with the paradigm that reddened broad-line AGNs represent a transitory phase in AGN evolution as described by the major merger model for black hole growth. Results from our pilot program demonstrate proof of concept that our selection technique is successful in discovering reddened quasars at z> 1 missed by optical surveys.

  5. Storm in a "Teacup": a radio-quiet quasar with ~10kpc radio-emitting bubbles and extreme gas kinematics

    CERN Document Server

    Harrison, C M; Alexander, D M; Bauer, F E; Edge, A C; Hogan, M T; Mullaney, J R; Swinbank, A M

    2014-01-01

    We present multi-frequency (1-8 GHz) VLA data, combined with VIMOS IFU data and HST imaging, of a z=0.085 radio-quiet type 2 quasar (with L(1.4GHz)~5e23 W/Hz and L(AGN)~2e45 erg/s). Due to the morphology of its emission-line region, the target (J1430+1339) has been referred to as the Teacup AGN in the literature. We identify "bubbles" of radio emission that are extended ~10-12 kpc to both the east and west of the nucleus. The edge of the brighter eastern bubble is co-spatial with an arc of luminous ionized gas. We also show that the Teacup AGN hosts a compact radio structure, located ~0.8 kpc from the core position, at the base of the eastern bubble. This radio structure is co-spatial with an ionized outflow with an observed velocity of v=-760 km/s. This is likely to correspond to a jet, or possibly a quasar wind, interacting with the interstellar medium at this position. The large-scale radio bubbles appear to be inflated by the central AGN, which indicates that the AGN can also interact with the gas on >~10...

  6. Clear evidence for the early triggering of a luminous quasar-like AGN in a major, gas rich merger

    CERN Document Server

    Bessiere, Patricia S; Almeida, Cristina Ramos; Martin, Montserrat Villar

    2013-01-01

    We present deep, intermediate resolution, long slit Gemini GMOS-S optical spectra of the SDSS type II quasar J002531-104022, which is a highly disturbed system currently undergoing a major merger event. We use these data to model the ages and reddenings of the stellar populations in three distinct spatial regions and find a remarkable uniformity in the properties of the young stellar populations (YSP) that dominate the optical spectra. The YSPs are all found to have relatively young ages (tysp < 40$ Myr), strongly implying that the latest episode of star formation and quasar activity have been triggered quasi-simultaneously. The lack of reddening deduced from both continuum modelling and the measured Balmer decrements (E(B-V) <0.3) suggests that starburst and/or AGN induced outflows have already effectively removed a substantial proportion of the gas and dust from the central region. These findings starkly contrast with model predictions which suggest an offset of a few 100 Myr between the peak of merge...

  7. Radio spectra and polarisation properties of a bright sample of Radio-Loud Broad Absorption Line Quasars

    CERN Document Server

    Bruni, G; Salerno, E; Montenegro-Montes, F M; Carballo, R; Benn, C R; González-Serrano, J I; Holt, J; Jiménez-Luján, F

    2012-01-01

    The origin of broad-absorption-line quasars (BAL QSOs) is still an open issue. Accounting for ~20% of the QSO population, these objects present broad absorption lines in their optical spectra generated from outflows with velocities up to 0.2c. In this work we present the results of a multi-frequency study of a well-defined radio-loud BAL QSO sample, and a comparison sample of radio-loud non-BAL QSOs, both selected from the Sloan Digital Sky Survey (SDSS). We aim to test which of the currently-popular models for the BAL phenomenon - `orientation' or 'evolutionary' - best accounts for the radio properties of BAL quasars. Observations from 1.4 to 43 GHz have been obtained with the VLA and Effelsberg telescopes, and data from 74 to 408 MHz have been compiled from the literature. The fractions of candidate GHz-peaked sources are similar in the two samples (36\\pm12% vs 23\\pm8%), suggesting that BAL QSOs are not generally younger than non-BAL QSOs. BAL and non-BAL QSOs show a large range of spectral indices, consist...

  8. Tracing the Outflow of a z=0.334 FeLoBAL: New Constraints from Low-Ionization Absorbers in FBQS J1151+3822

    CERN Document Server

    Lucy, Adrian B; Terndrup, Donald M; Dietrich, Matthias; Gallagher, Sarah C

    2014-01-01

    We show for the first time that FBQS J1151+3822 is an iron low-ionization broad absorption line quasar (FeLoBAL QSO), the second-brightest and second-closest known example of this class. He I* and Fe II together act as an effective analytical tool, allowing us to obtain useful kinematic constraints from photoionization models of the outflow without needing to assume any particular acceleration model. The main outflow's log ionization parameter is -1.5, the log hydrogen density [cm^(-3)] 5.5 to 8, the log hydrogen column density [cm^(-2)] 21.7 to 21.9, the absorption radius 7.2 to 127 pc, and the kinetic luminosity 0.16 to 4.5% of the bolometric luminosity. We obtain line-of-sight covering fractions of ~0.25 for strong Fe II, ~0.5 for He I*, and ~0.6 for Mg II. Narrower and shallower absorption lines from weaker Fe II and Mn II with outflow velocity ~3400 km/s have appeared between 2005 and 2011, suggesting that dense cores may have condensed inside the main outflow. Consideration of the literature might sugge...

  9. The Co-Formation of Spheroids and Quasars Traced in their Clustering

    CERN Document Server

    Hopkins, P F; Hernquist, L; Coil, A L; Myers, A D; Cox, T J; Spergel, D N; Hopkins, Philip F.; Lidz, Adam; Hernquist, Lars; Coil, Alison L.; Myers, Adam D.; Cox, Thomas J.; Spergel, David N.

    2006-01-01

    We compare observed clustering of quasars and galaxies as a function of redshift, mass, luminosity, & color/morphology, to constrain models of quasar fueling and spheroid-BH co-evolution. High redshift quasars are shown to be drawn from progenitors of local early-type galaxies, with the characteristic quasar luminosity L* reflecting a characteristic mass of 'active' BH/host populations at each redshift. Evolving observed high-z quasar clustering to z=0 predicts a trend of clustering in 'quasar remnants' as a function of stellar mass identical to that observed for early-types. However, quasar clustering does not simply reflect observed early (or late)-type populations; at each redshift, quasars cluster as an 'intermediate' population. Comparing with the age of elliptical stellar populations reveals that this 'intermediate' population represents those ellipticals undergoing or terminating their final significant star formation at each epoch. Assuming that quasar triggering is associated with the formation/t...

  10. Infrared observations of the X-ray quasars 0241+622 and MR2251-178

    Science.gov (United States)

    Soifer, B. T.; Neugebauer, G.; Matthews, K.

    1979-01-01

    Infrared observations of the recently discovered X-ray quasars 0241+622 and MR2251-178 are reported. Broadband photometry of both quasars was conducted in the 1.25 to 20 micron range and spectrophotometry of 0241+622 was carried out from 1.5 to 2.5 microns. The IR energy distributions of 0241+622, MR2251-178 and the X-ray quasar 3C273 are presented, noting that for wavelengths less than 10 microns, the energy distributions of all three quasars are similar and cannot be distinguished from those of other low redshift quasars. The observed IR, visual and X-ray luminosities of the three quasars are compared and are found not to be strongly correlated. It is remarked, however, that the three X-ray quasars are the brightest known quasars at IR and visual wavelengths, which supports the suggestion that all quasars are bright X-ray emitters.

  11. Numerical Study on Outflows in Seyfert Galaxies I: Narrow Line Region Outflows in NGC 4151

    Science.gov (United States)

    Mou, Guobin; Wang, Tinggui; Yang, Chenwei

    2017-07-01

    The origin of narrow line region (NLR) outflows remains unknown. In this paper, we explore the scenario in which these outflows are circumnuclear clouds driven by energetic accretion disk winds. We choose the well-studied nearby Seyfert galaxy NGC 4151 as an example. By performing 3D hydrodynamical simulations, we are able to reproduce the radial distributions of velocity, mass outflow rate, and kinetic luminosity of NLR outflows in the inner 100 pc deduced from spatial resolved spectroscopic observations. The demanded kinetic luminosity of disk winds is about two orders of magnitude higher than that inferred from the NLR outflows, but is close to the ultrafast outflows (UFO) detected in the X-ray spectrum and a few times lower than the bolometric luminosity of the Seyfert. Our simulations imply that the scenario is viable for NGC 4151. The existence of the underlying disk winds can be confirmed by their impacts on higher density ISM, e.g., shock excitation signs, and the pressure in NLR.

  12. ELM-KNN for photometric redshift estimation of quasars

    Science.gov (United States)

    Zhang, Yanxia; Tu, Yang; Zhao, Yongheng; Tian, Haijun

    2017-06-01

    We explore photometric redshift estimation of quasars with the SDSS DR12 quasar sample. Firstly the quasar sample is separated into three parts according to different redshift ranges. Then three classifiers based on Extreme Learning Machine (ELM) are created in the three redshift ranges. Finally k-Nearest Neighbor (kNN) approach is applied on the three samples to predict photometric redshifts of quasars with multiwavelength photometric data. We compare the performance with different input patterns by ELM-KNN with that only by kNN. The experimental results show that ELM-KNN is feasible and superior to kNN (e.g. rms is 0.0751 vs. 0.2626 for SDSS sample), in other words, the ensemble method has the potential to increase regressor performance beyond the level reached by an individual regressor alone and will be a good choice when facing much more complex data.

  13. The Doppler Effect: A Consideration of Quasar Redshifts.

    Science.gov (United States)

    Gordon, Kurtiss J.

    1980-01-01

    Provides information on the calculation of the redshift to blueshift ratio introduced by the transverse Doppler effect at relativistic speeds. Indicates that this shift should be mentioned in discussions of whether quasars are "local" rather than "cosmological" objects. (GS)

  14. High-redshift SDSS Quasars with Weak Emission Lines

    DEFF Research Database (Denmark)

    Diamond-Stanic, Aleksandar M.; Fan, Xiaohui; Brandt, W. N.

    2009-01-01

    We identify a sample of 74 high-redshift quasars (z > 3) with weak emission lines from the Fifth Data Release of the Sloan Digital Sky Survey and present infrared, optical, and radio observations of a subsample of four objects at z > 4. These weak emission-line quasars (WLQs) constitute a prominent...... tail of the Lya + N v equivalent width distribution, and we compare them to quasars with more typical emission-line properties and to low-redshift active galactic nuclei with weak/absent emission lines, namely BL Lac objects. We find that WLQs exhibit hot (T ~ 1000 K) thermal dust emission and have...... rest-frame 0.1-5 µm spectral energy distributions that are quite similar to those of normal quasars. The variability, polarization, and radio properties of WLQs are also different from those of BL Lacs, making continuum boosting by a relativistic jet an unlikely physical interpretation. The most...

  15. A Survey for Very High-Redshift Quasars

    Science.gov (United States)

    Lemley, Shelley R.

    1995-12-01

    I have been conducting a deep, three color survey for very high redshift quasars and will present information on how my candidates, which are awaiting spectroscopic confirmation, have been selected. The survey involves direct imaging through Gunn gri filters using a 2048 x 2048 STIS ccd chip and Cerro Tololo's Curtis Scmidt Telescope. Quasar candidates in the range 4.2 5 candidates have large r - i values and g - r values near zero. Before beginning the survey, test observations using this selection method were made of two known quasars with redshifts of 4.5 and 4.7. The quasars were successfully relocated by the technique and several candidates, which will also be observed for spectroscopic confirmation, were selected from those two fields. To date, 13 square degrees have been surveyed.

  16. 30 GHz monitoring of broad absorption line (BAL) quasars

    CERN Document Server

    Ceglowski, Maciej; Pazderska, Bogna; Gawronski, Marcin

    2014-01-01

    Broad absorption line (BAL) quasars have been studied for over thirty years. Yet it is still unclear why and when we observe broad absorption lines in quasars. Is this phenomenon caused by geometry or is it connected with the evolution process? Variability of the BAL quasars, if present, can give us information about their orientation, namely it can indicate whether they are oriented more pole-on. Using the Torun 32-metre dish equipped with the One Centimetre Receiver Array (OCRA) we have started a monitoring campaign of a sample of compact radio-loud BAL quasars. This 30 GHz variability monitoring program supplements the high-resolution interferometric observations of these objects we have carried out with the EVN and VLBA.

  17. False periodicities in quasar time-domain surveys

    CERN Document Server

    Vaughan, S; Markowitz, A G; Huppenkothen, D; Middleton, M J; Alston, W N; Scargle, J D; Farr, W M

    2016-01-01

    There have recently been several reports of apparently periodic variations in the light curves of quasars, e.g. PG 1302-102 by Graham et al. (2015a). Any quasar showing periodic oscillations in brightness would be a strong candidate to be a close binary supermassive black hole and, in turn, a candidate for gravitational wave studies. However, normal quasars -- powered by accretion onto a single, supermassive black hole -- usually show stochastic variability over a wide range of timescales. It is therefore important to carefully assess the methods for identifying periodic candidates from among a population dominated by stochastic variability. Using a Bayesian analysis of the light curve of PG 1302-102, we find that a simple stochastic process is preferred over a sinusoidal variations. We then discuss some of the problems one encounters when searching for rare, strictly periodic signals among a large number of irregularly sampled, stochastic time series, and use simulations of quasar light curves to illustrate ...

  18. The Doppler Effect: A Consideration of Quasar Redshifts.

    Science.gov (United States)

    Gordon, Kurtiss J.

    1980-01-01

    Provides information on the calculation of the redshift to blueshift ratio introduced by the transverse Doppler effect at relativistic speeds. Indicates that this shift should be mentioned in discussions of whether quasars are "local" rather than "cosmological" objects. (GS)

  19. Effect of clear cutting on snow accumulation and water outflow at Fraser, Colorado

    Directory of Open Access Journals (Sweden)

    C. A. Troendle

    1997-01-01

    Full Text Available This paper compares of snowpack accumulation and ablation, evapotranspiration, and water outflow from clearcut and forested plots within a high elevation (2900 m mixed conifer forest at the Fraser Experimental Forest near Fraser, Colorado, USA. Also presented is a method for defining contributing area where outflow is measured from unbounded plots. Plots were monitored from 1980 to 1990 and again in 1993. The clearcut plot was harvested in late 1984. Evapotranspiration (ET of the forested plot at zero discharge (ETo was estimated at 426 mm while the ET was 500 mm at the mean precipitation of 596 mm. ET was dependent on precipitation with about 28% of precipitation input in excess of 426 mm contributing to increased ET, while the remainder contributed to increased outflow. During the six monitored post-harvest years, Peak Water Equivalent of the snowpack averaged 36% higher on the cut plot than on the control, and the mean discharge increased from 85 mm to 356 mm. Area estimates were obtained from the slopes of the regression of outflow on precipitation inputs. Hydrologic parameters corresponded closely to those previously determined at Fraser Experimental Forest using other methods, lending credence to the validity of the area estimates.

  20. Measuring the dark energy with quasar clustering

    CERN Document Server

    Calvão, M O; Waga, I

    2002-01-01

    We show, through Monte Carlo simulations, that the Alcock-Pazynski test, as applied to quasar clustering, is a powerful tool to probe the cosmological density and equation of state parameters, Omega_{m0}, Omega_{x0} and w. By taking into account peculiar velocity corrections to the correlation function we obtain, for the Two-Degree Field QSO Redshift Survey (2QZ), the predicted 1\\sigma and 2\\sigma confidence contours. It turns out that the test is competitive with future supernova and galaxy number count ones, besides being complementary to them, for fixed curvature. In particular, we find out that it is especially sensitive to the difference Omega_{m0}-Omega_{Lambda 0}, thus being ideal to combine with CMB results.

  1. Quasar Absorption Lines and SDSS Galaxies

    Science.gov (United States)

    Shoemaker, Emileigh Suzanne; Scott, Jennifer E.; Oldak, Katarzyna

    2017-01-01

    We present the results of a study of the sightlines of 45 low redshift quasars (0.06 COS that lie within the footprint of the Sloan Digital Sky Survey. We use both the SDSS DR12 galaxy photometric data, including photometric redshifts, and the measured properties of the absorbers along with the known absorption characteristics of the intergalactic medium and the circumgalactic medium of galaxies to assign the most probable galaxy matches for each absorber in the sample, using estimated galaxy luminosities and virial radii as a discriminator. We show that the scheme can recover known galaxy-absorber matches found from spectroscopic data and thus provides a method for identifying likely pairs in photometric data sets as well as targets for spectroscopic follow up.

  2. Evidence for feedback in action from the molecular gas content in the z ~ 1.6 outflowing QSO XID2028

    Science.gov (United States)

    Brusa, M.; Feruglio, C.; Cresci, G.; Mainieri, V.; Sargent, M. T.; Perna, M.; Santini, P.; Vito, F.; Marconi, A.; Merloni, A.; Lutz, D.; Piconcelli, E.; Lanzuisi, G.; Maiolino, R.; Rosario, D.; Daddi, E.; Bongiorno, A.; Fiore, F.; Lusso, E.

    2015-06-01

    Aims: Gas outflows are believed to play a pivotal role in shaping galaxies, as they regulate both star formation and black hole growth. Despite their ubiquitous presence, the origin and the acceleration mechanism of these powerful and extended winds is not yet understood. Direct observations of the cold gas component in objects with detected outflows at other wavelengths are needed to assess the impact of the outflow on the host galaxy interstellar medium (ISM). Methods: We observed with the Plateau de Bure Interferometer an obscured quasar at z ~ 1.5, XID2028, for which the presence of an ionized outflow has been unambiguously signalled by NIR spectroscopy. The detection of 12CO(3-2) emission in this source allows us to infer the molecular gas content and compare it to the ISM mass derived from the dust emission. We then analyzed the results in the context of recent insights on scaling relations, which describe the gas content of the overall population of star-forming galaxies at a similar redshifts. Results: The star formation efficiency (~100) and gas mass (Mgas = 2.1-9.5 × 1010 M⊙) inferred from the CO(3-2) line depend on the underlying assumptions on the excitation of the transition and the CO-to-H2 conversion factor. However, the combination of this information and the ISM mass estimated from the dust mass suggests that the ISM/gas content of XID2028 is significantly lower than expected for its observed M⋆, sSFR and redshift, based on the most up-to-date calibrations (with gas fraction France), MPG (Germany) and IGN (Spain).A FITS file for the spectrum shown in Fig. 1 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/578/A11

  3. Does circular polarisation reveal the rotation of quasar engines?

    OpenAIRE

    Ensslin, Torsten A.

    2002-01-01

    Many radio sources like quasars, blazars, radio galaxies, and micro-quasars exhibit circular polarisation (CP) with surprising temporal persistent handedness. As a possible explanation we propose that the CP is due to Faraday conversion (FC) of linear polarisation (LP) synchrotron light which propagates along a line-of-sight (LOS) through twisted magnetic fields. The rotational nature of accretion flows onto black holes naturally generates the required magnetic twist in the emission region, i...

  4. From local active galactic nuclei to early quasars

    Energy Technology Data Exchange (ETDEWEB)

    Cavaliere, A.; Giallongo, E.; Vagnetti, F.

    1985-09-15

    To close the gap between the local luminosity function of the optically selected active galactic nuclei and the population properties of distant (z< or approx. =2) quasars, we propose a model of differential luminosity evolution which is astrophysically based and contains a minimal number of free parameters. We discuss the advantages of the model and its predictions, and indicate how to extend it for z > 2 to cover the beginning of the quasar era.

  5. Quasar absorption spectra and the structure of the universe

    Energy Technology Data Exchange (ETDEWEB)

    Doroshkevich, A.G.

    1984-03-01

    Analysis of the spacing between absorption-line systems in quasar spectra and comparison against deep optical survey data for the separation between superclusters of galaxies indicates that the absorption originates in the superclusters. Supported by analogous data on the absorbing gas in the galactic and Magellanic Cloud halos, this inference sharpens theoretical conclusions as to the properties of superclusters. The problem of the unidentified quasar absorption lines is discussed.

  6. What sparks the radio-loud phase of nearby quasars?

    Science.gov (United States)

    Coziol, Roger; Andernach, Heinz; Torres-Papaqui, Juan Pablo; Ortega-Minakata, René Alberto; Moreno del Rio, Froylan

    2017-04-01

    To better constrain the hypotheses proposed to explain why only a few quasars are radio loud (RL), we compare the characteristics of 1958 nearby (z ≤ 0.3) SDSS (Sloan Digital Sky Survey) quasars, covered by the FIRST (Faint Images of the Radio Sky at Twenty-centimeters) and NVSS (NRAO VLA Sky Survey) radio surveys. Only 22 per cent are RL with log (L1.4 GHz) ≥ 22.5 W Hz-1, the majority being compact (C), weak radio sources (WRS), with log (L1.4 GHz) radio morphologies: 3 per cent have a core and a jet (J), 2 per cent have a core with one lobe (L), and 10 per cent have a core with two lobes (T), the majority being powerful radio sources (PRS), with log (L1.4 GHz) ≥ 24.5 W Hz-1. In general, RL quasars have higher bolometric luminosities and ionization powers than radio-quiet (RQ) quasars. The WRS have comparable black hole (BH) masses as the RQ quasars, but higher accretion rates or radiative efficiencies. The PRS have higher BH masses than the WRS, but comparable accretion rates or radiative efficiencies. The WRS also have higher FWHM_{[O iii]} than the PRS, consistent with a coupling of the spectral characteristics of the quasars with their radio morphologies. Inspecting the SDSS images and applying a neighbour search algorithm reveal no difference between the RQ and RL quasars of their host galaxies, environments, and interaction. Our results prompt the conjecture that the phenomenon that sparks the RL phase in quasars is transient, intrinsic to the active galactic nuclei, and stochastic, due to the chaotic nature of the accretion process of matter on to the BHs.

  7. Galactic Outflows and Photoionization Heating in the Reionization Epoch

    CERN Document Server

    Finlator, K; Özel, F

    2011-01-01

    We carry out a new suite of cosmological radiation hydrodynamic simulations and explore the relative impacts on reionization-epoch star formation of galactic outflows and photoionization heating. By itself, an extragalactic ultraviolet background (EUVB) suppresses the luminosity function by less than 50% at z=6, overproducing the observed galaxy abundance by a factor of 3-5. Galactic outflows restore agreement with observations without preventing Population II star formation from reionizing the Universe by z=6. The resulting EUVB suppresses star formation in halos with virial temperatures below 10^5K but has a weaker impact in more massive halos. Nonetheless, the low-mass halos contribute up to 50% of all ionizing photons owing to the EUVB's inhomogeneity. Overall, star formation rate scales as halo mass M_h to the 1.3-1.4 in halos with $M_h=10^{8.2--10.2}\\msun$. This is a steeper dependence than is often assumed in reionization models, boosting the expected power spectrum of 21 centimeter fluctuations on lar...

  8. Future dark energy constraints from measurements of quasar parallax: Gaia, SIM and beyond

    Science.gov (United States)

    Ding, Fiona; Croft, Rupert A. C.

    2009-08-01

    , there will be small additional contributions from image centroiding of variable sources, quasar peculiar motions and weak microlensing by stars along the line of sight.

  9. The Sloan Digital Sky Survey quasar catalog: ninth data release

    CERN Document Server

    Pâris, Isabelle; Aubourg, Eric; Bailey, Stephen; Ross, Nicholas P; Myers, Adam D; Strauss, Michael A; Anderson, Scott F; Arnau, Eduard; Bautista, Julian; Bizyaev, Dmitry; Bolton, Adam S; Bovy, Jo; Brandt, William N; Brewington, Howard; Brownstein, Joel R; Busca, Nicolas; Capellupo, Daniel; Carithers, William; Croft, Rupert A C; Dawson, Kyle; Delubac, Timothée; Ebelke, Garrett; Eisenstein, Daniel J; Engelke, Philip; Fan, Xiaohui; Ak, Nur Filiz; Finley, Hayley; Font-Ribera, Andreu; Ge, Jian; Gibson, Robert R; Hall, Patrick B; Hamann, Fred; Hennawi, Joseph F; Ho, Shirley; Hogg, David W; Ivezic, Zeljko; Jiang, Linhua; Kimball, Amy E; Kirkby, David; Kirkpatrick, Jessica A; Lee, Khee-Gan; Goff, Jean-Marc Le; Lundgren, Britt; MacLeod, Chelsea L; Malanushenko, Elena; Malanushenko, Viktor; Maraston, Claudia; McGreer, Ian D; McMahon, Richard G; Miralda-Escudé, Jordi; Muna, Demitri; Noterdaeme, Pasquier; Oravetz, Daniel; Palanque-Delabrouille, Nathalie; Pan, Kaike; Perez-Fournon, Ismaël; Pieri, Matthew M; Richards, Gordon T; Rollinde, Emmanuel; Sheldon, Erin S; Schlegel, David J; Schneider, Donald P; Slosar, Anze; Shelden, Alaina; Shen, Yue; Simmons, Audrey; Snedden, Stephanie; Suzuki, Nao; Tinker, Jeremy; Viel, Matteo; Weaver, Benjamin A; Weinberg, David H; White, Martin; Wood-Vasey, W Michael; Yèche, Christophe

    2012-01-01

    We present the Data Release 9 Quasar (DR9Q) 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 survey, are spectrocopically confirmed as quasars via visual inspection, have luminosities Mi[z=2]2.15$ (61,931) is ~2.8 times larger than the number of z>2.15 quasars previously known. Redshifts and FWHMs are provided for the strongest emission lines (CIV, CIII], MgII). The catalog identifies 7,533 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 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.

  10. New Quasar Surveys With WIRO: Planning and Depth of Observations

    Science.gov (United States)

    Bassett, Neil; Deam, Sophie; Dixon, Don; Griffith, Emily; Harvey, William; Lee, Daniel; Lyke, Bradley; Haze Nunez, Evan; Parziale, Ryan; Witherspoon, Catherine; Myers, Adam D.; Findlay, Joseph; Kobulnicky, Henry A.; Dale, Daniel A.

    2017-01-01

    The Wyoming Infrared Observatory (WIRO) 2.3-meter telescope is used to observe a section of sky behind the outer regions of the galaxy M33 with the goal of identifying previously undiscovered quasar candidates. We choose the regions based on visibility during the time of year the observations are taken as well as regions in which few quasars have been detected by previous surveys. DS9 and Python are used to determine the coordinates of our desired field centers for photometric observations in the u, g, r, and i Sloan filters. Exposure times are chosen such that the depth in each filter is greater than an apparent magnitude of 21. This depth allows us to identify quasar candidates which are fainter than other quasar surveys in the same vicinity. Future spectroscopic observations will be able to confirm if the candidates are indeed quasars and spectra of the confirmed quasars can be used to study the extended gaseous region of M33. This work is supported by the National Science Foundation under REU grant AST 1560461.

  11. DISSECTING THE QUASAR MAIN SEQUENCE: INSIGHT FROM HOST GALAXY PROPERTIES

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Jiayi [Tsinghua Center for Astrophysics, Department of Physics, Tsinghua University, Beijing 100084 (China); Shen, Yue [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)

    2015-05-01

    The diverse properties of broad-line quasars appear to follow a well-defined main sequence along which the optical Fe ii strength increases. It has been suggested that this sequence is mainly driven by the Eddington ratio (L/L{sub Edd}) of the black hole (BH) accretion. Shen and Ho demonstrated with quasar clustering analysis that the average BH mass decreases with increasing Fe ii strength when quasar luminosity is fixed, consistent with this suggestion. Here we perform an independent test by measuring the stellar velocity dispersion σ{sub *} (hence, the BH mass via the M–σ{sub *} relation) from decomposed host spectra in low-redshift Sloan Digital Sky Survey quasars. We found that at fixed quasar luminosity, σ{sub *} systematically decreases with increasing Fe ii strength, confirming that the Eddington ratio increases with Fe ii strength. We also found that at fixed luminosity and Fe ii strength, there is little dependence of σ{sub *} on the broad Hβ FWHM. These new results reinforce the framework that the Eddington ratio and orientation govern most of the diversity seen in broad-line quasar properties.

  12. The Sloan Digital Sky Survey Quasar Catalog: twelfth data release

    CERN Document Server

    Pâris, Isabelle; Ross, Nicholas P; Myers, Adam D; Aubourg, Éric; Streblyanska, Alina; Bailey, Stephen; Armengaud, Éric; Palanque-Delabrouille, Nathalie; Yèche, Christophe; Hamann, Fred; Strauss, Michael A; Albareti, Franco D; Bovy, Jo; Bizyaev, Dmitry; Brandt, W Niel; Brusa, Marcella; Buchner, Johannes; Comparat, Johan; Croft, Rupert A C; Dwelly, Tom; Fan, Xiaohui; Font-Ribera, Andreu; Ge, Jian; Georgakakis, Antonis; Hall, Patrick B; Jian, Linhua; Kinemuchi, Karen; Malanushenko, Elena; Malanushenko, Viktor; McMahon, Richard G; Menzel, Marie-Luise; Merloni, Andrea; Nandra, Kirpal; Noterdaeme, Pasquier; Oravetz, Daniel; Pan, Kaike; Pieri, Matthew M; Prada, Francisco; Salvato, Mara; Schlegel, David J; Schneider, Donald P; Simmons, Audrey; Viel, Matteo; Weinberg, David H; Zhu, Liu

    2016-01-01

    We present the Data Release 12 Quasar catalog (DR12Q) from the Baryon Oscillation Spectroscopic Survey (BOSS) of the SDSS-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 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 (CIV, CIII], MgII). 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 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 PTF multi-epoch photometry. The catalog also contains X-ray, ultraviolet, near-infrared, and radio emission properti...

  13. An extinction curve template for intrinsically reddened quasars

    CERN Document Server

    Zafar, Tayyaba; Watson, Darach; Fynbo, Johan P U; Krogager, Jens-Kristian; Zafar, Nosheen; Saturni, Francesci G; Geier5, Stefan; Venemans, Bram P

    2015-01-01

    We analyze the near-infrared to UV data of 16 quasars with redshifts ranging from 0.71 $<$ $z$ $<$ 2.13 to investigate dust extinction properties. The sample presented in this work is obtained from the High $A_V$ Quasar (HAQ) survey. The quasar candidates were selected from the Sloan Digital Sky Survey (SDSS) and the UKIRT Infrared Deep Sky Survey (UKIDSS), and follow-up spectroscopy was carried out at the Nordic Optical Telescope (NOT) and the New Technology Telescope (NTT). To study dust extinction curves intrinsic to the quasars, from the HAQ survey we selected 16 cases where the Small Magellanic Cloud (SMC) law could not provide a good solution to the spectral energy distributions (SEDs). We derived the extinction curves using Fitzpatrick & Massa 1986 (FM) law by comparing the observed SEDs to the combined quasar template from Vanden Berk et al. 2001 and Glikman et al. 2006. The derived extinction, $A_V$, ranges from 0.2-1.0 mag. All the individual extinction curves of our quasars are steeper ($...

  14. Host Galaxies of Young Dust-Reddened Quasars

    Science.gov (United States)

    Urrutia, T.; Lacy, M.; Becker, R.; Glikman, E.

    2009-10-01

    We present results on a multiwavelength campaign to identify the nature of dust-reddened Type 1 quasars. These quasars were selected by matching FIRST, 2MASS and very red optical counterparts with r'-K > 5. We find a very high fraction of Low Ionization Broad Absorption Line Quasars (LoBALs) among AGN selected with this method, perhaps a sign of quasar feedback. From X-ray observations and Balmer decrement measurements, the obscuring dust is most likely located in a cold absorber such as the host galaxy, rather than from a torus near the AGN. Hubble ACS imaging of a sub-sample of these sources showed a very high fraction of interacting and merging systems. The quasars appear to be very young in which dust from the merging galaxies is still settling in. Spitzer IRS and MIPS data show star formation signatures and deep Silicate absorption features in these objects, but overall the quasar is the dominant source in the Mid-infrared.

  15. Eight-Dimensional Mid-Infrared/Optical Bayesian Quasar Selection

    CERN Document Server

    Richards, Gordon T; Lacy, Mark; Myers, Adam D; Nichol, Robert C; Zakamska, Nadia L; Brunner, Robert J; Brandt, W N; Gray, Alexander G; Parejko, John K; Ptak, Andrew; Schneider, Donald P; Storrie-Lombardi, Lisa J; Szalay, Alexander S

    2008-01-01

    We explore the multidimensional, multiwavelength selection of quasars from mid-IR (MIR) plus optical data, specifically from Spitzer-IRAC and the Sloan Digital Sky Survey (SDSS). We apply modern statistical techniques to combined Spitzer MIR and SDSS optical data, allowing up to 8-D color selection of quasars. Using a Bayesian selection method, we catalog 5546 quasar candidates to an 8.0um depth of 56uJy over an area of ~24 sq. deg; ~70% of these candidates are not identified by applying the same Bayesian algorithm to 4-color SDSS optical data alone. Our selection recovers 97.7% of known type 1 quasars in this area and greatly improves the effectiveness of identifying 3.5quasars. Even using only the two shortest wavelength IRAC bandpasses (3.6 and 4.5um), it is possible to use our Bayesian techniques to select quasars with 97% completeness and as little as 10% contamination. This sample has a photometric redshift accuracy of 93.6% (DeltaZ +/- 0.3), remaining roughly constant when the two reddest MI...

  16. A New Model for Dark Matter Halos Hosting Quasars

    CERN Document Server

    Cen, Renyue

    2014-01-01

    A new model for quasar-hosting dark matter halos, meeting two physical conditions, is put forth. First, significant interactions are taken into consideration to trigger quasar activities. Second, satellites in very massive halos at low redshift are removed from consideration, due to their deficiency of cold gas. We analyze the {\\em Millennium Simulation} to find halos that meet these two conditions and simultaneously match two-point auto-correlation functions of quasars and cross-correlation functions between quasars and galaxies at $z=0.5-3.2$. %The found halos have some distinct properties worth noting. The masses of found quasar hosts decrease with decreasing redshift, with the mass thresholds being $[(2-5)\\times 10^{12}, (2-5)\\times 10^{11}, (1-3)\\times 10^{11}]\\msun$ for median luminosities of $\\sim[10^{46}, 10^{46}, 10^{45}]$erg/s at $z=(3.2, 1.4, 0.53)$, respectively, an order of magnitude lower than those inferred based on halo occupation distribution modeling. In this model quasar hosts are primarily...

  17. Dissecting the Quasar Main Sequence: Insight from Host Galaxy Properties

    Science.gov (United States)

    Sun, Jiayi; Shen, Yue

    2015-05-01

    The diverse properties of broad-line quasars appear to follow a well-defined main sequence along which the optical Fe ii strength increases. It has been suggested that this sequence is mainly driven by the Eddington ratio (L/LEdd) of the black hole (BH) accretion. Shen & Ho demonstrated with quasar clustering analysis that the average BH mass decreases with increasing Fe ii strength when quasar luminosity is fixed, consistent with this suggestion. Here we perform an independent test by measuring the stellar velocity dispersion σ* (hence, the BH mass via the M-σ* relation) from decomposed host spectra in low-redshift Sloan Digital Sky Survey quasars. We found that at fixed quasar luminosity, σ* systematically decreases with increasing Fe ii strength, confirming that the Eddington ratio increases with Fe ii strength. We also found that at fixed luminosity and Fe ii strength, there is little dependence of σ* on the broad Hβ FWHM. These new results reinforce the framework that the Eddington ratio and orientation govern most of the diversity seen in broad-line quasar properties.

  18. Correlations between Optical Variability and Physical Parameters of Quasars

    Indian Academy of Sciences (India)

    Wenwen Zuo; Xue-Bing Wu; Yi-Qing Liu; Cheng-Liang Jiao

    2014-09-01

    Optical variability is an important feature of quasars. Taking advantage of a larger sample of 7658 quasars from SDSS Stripe 82 and relatively more photometric data points for each quasar, we estimate their variability amplitudes and divide the sample into small bins of various parameters. An anticorrelation between variability amplitude and rest-frame wavelength is found. Variability increases as either luminosity or Eddington ratio decreases. The relationship between variability and black hole mass is uncertain. The intrinsic distribution of variability amplitudes for radio-loud and radio-quiet quasars are different. Both radio-loud and radio-quiet quasars exhibit a bluer-when-brighter chromatism. With the Shakura–Sunyaev disk model, we find that changes of accretion rate play an important role in producing the observed optical variability. However, the predicted positive correlation between variability and black hole mass seems to be inconsistent with the observed negative correlation between them in small bins of Eddington ratio, which suggests that other physical mechanisms may still need to be considered in modifying the simple accretion disk model. The different mechanisms in radio-loud and radio-quiet quasars are discussed.

  19. An astrophysics data program investigation of a synoptic study of quasar continua

    Science.gov (United States)

    Elvis, Martin

    1991-01-01

    A summary of the program is presented. The major product of the program, an atlas of quasar energy distributions, is presented in the appendices along with papers written as a result of this research. The topics covered in the papers include: (1) accurate galactic N(sub h) values toward quasars and active galactic nuclei (AGN); (2) weak bump quasars; (3) millimeter measurements of hard x ray selected active galaxies- implications for the nature of the continuous spectrum; (3) persistence and change in the soft x ray spectrum of the quasar PG1211+143; (4) the soft x ray excess in einstein quasar spectra; and (5) EXOSAT x ray spectra of quasars.

  20. The Large Quasar Reference Frame (LQRF). An Optical Representation of the ICRS

    Science.gov (United States)

    2009-10-01

    found in the USNO B1.0 and GSC2.3 catalogs, and from the SDSS Data Release 5. The initial positions are next placed onto UCAC2-based reference frames...are found for all the catalogs used (apart from the SDSS DR5), an empirical magnitude correction can be discussed for the GSC2.3 intermediate and...right) of the quasars found in the LQAC catalog. The highest density regions indi- cate the SDSS DR5 contribution.The scale represents the number of

  1. CHANDRA LETGS spectroscopy of ionized absorbers: The quasar MR 2251-178

    Science.gov (United States)

    Ramírez, J. M.; Komossa, S.; Burwitz, V.; Mathur, S.

    2008-04-01

    We analyze the Chandra Low Energy Transmission Grating Spectrometer (LETGS) observation of the quasar MR 2251-178. The warm absorber of MR 2251-178 is well described by a hydrogen column density of ≈ 2×10(21) cm(-2) , an ionization parameter log(xi) ≈ 0.6, and a global best-fit outflow velocity of ≈ -1100 km s(-1) . We find in the spectrum evidence of narrow absorption lines. The K_alpha and K_beta transitions of C VI and N VI ions display an outflow with (at least three) components traveling at ≈ -600, -2000 and -3000 km s(-1) . We measure a (0.1-2) keV flux of 2.58_{-0.04} (+0.03) ×10(-11) erg s cm(-2) s(-1) , and a (2-10) keV flux of 1.64_{-0.05} (+0.05) × 10(-11) erg s cm(-2) s(-1) . This flux implies that the nuclear source of MR 2251-178 is in a relatively low state. We did not find evidence for an extra cold material in the line of sight, that would be associated to the giant [O III] emission region surrounding the nucleus of MR 2251-178. If present, we can set an upper limit of ≈ 1.2×10(20) cm(-2) . The X-ray spectrum does not appear to show evidence for dusty material, though an upper limit in the neutral carbon and oxygen column densities can only be set to N_{CI} ≈ 2×10(19) cm(-2) and N_{OI} ≈ 9×10(19) cm(-2) , respectively.

  2. Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs): New z > 6 Quasar Survey with Subaru/HSC

    Science.gov (United States)

    Matsuoka, Yoshiki; SHELLQs Collaboration

    2017-01-01

    Quasars at high redshift are an important and unique probe of the distant Universe, for understanding the origin and progress of cosmic reionization, the early growth of supermassive black holes, and the evolution of quasar host galaxies and their dark matter halos, among other topics. We are currently carrying out a new spectroscopic survey, called SHELLQs (Subaru High-z Exploration of Low-Luminosity Quasars), to search for low-luminosity quasars at z > 6. By exploiting the exquisite imaging data produced by the Subaru Hyper Suprime-Cam (HSC) survey, we aim to probe quasar luminosities down to M1450 ~ -22 mag, i.e., below the classical threshold between quasars and Seyfert galaxies. Candidate selection is performed by combining several photometric approaches including a Bayesian probabilistic algorithm. A large spectroscopic observing program is underway, using Subaru/FOCAS, GTC/OSIRIS, and Gemini/GMOS; in particular, SHELLQs has been approved as a Subaru intensive program to use 20 nights in the coming four semesters. As of August 2016, we have discovered ~40 quasars and bright galaxies at z ~ 6 and beyond, from the first 100 deg2 of the HSC survey (Matsuoka et al. 2016, ApJ, 828, 26). Surprisingly, we are starting to see the steep rise of the luminosity function of high-z galaxies, compared with that of quasars, at magnitudes fainter than M1450 ~ -22 mag or zAB ~ 24 mag. Multi-wavelength follow-up studies of the discovered objects as well as further survey observations are ongoing.

  3. Influence of Mediterranean Outflow on climate

    Science.gov (United States)

    Rahmstorf, Stefan

    A cover article in Eos last year [Johnson, 1997] called for a dam across the Strait of Gibraltar to prevent a new Ice Age. In this article, R. G. Johnson argued that reduced Nile River flow after building the Aswan Dam increases Mediterranean Sea salinity, leading to enhanced outflow of salty water into the Atlantic Ocean. This, in turn, would alter the thermohaline (that is, temperature and salinity driven) circulation of the Atlantic, heat up the Labrador Sea and enhance evaporation there, and increase snowfall in Canada until a new ice sheet builds up. Ocean circulation model experiments, however, suggest that this fear is unfounded. While Mediterranean saltwater outflow (Figure 1a) does appear to have some effect on North Atlantic circulation and surface climate, the change in Mediterranean salt budget resulting from the Aswan Dam is far too small to have any noticeable impact.

  4. Hepatic venous outflow obstruction: Three similar syndromes

    Institute of Scientific and Technical Information of China (English)

    Ulas Darda Bayraktar; Soley Seren; Yusuf Bayraktar

    2007-01-01

    Our goal is to provide a detailed review of venoocclusive disease (VOD), Budd-Chiari syndrome (BCS),and congestive hepatopathy (CH), all of which results in hepatic venous outflow obstruction. This is the first article in which all three syndromes have been reviewed,enabling the reader to compare the characteristics of these disorders. The histological findings in VOD, BCS,and CH are almost identical: sinusoidal congestion and cell necrosis mostly in perivenular areas of hepatic acini which eventually leads to bridging fibrosis between adjacent central veins. Tender hepatomegaly with jaundice and ascites is common to all three conditions.However, the clinical presentation depends mostly on the extent and rapidity of the outflow obstruction.Although the etiology and treatment are completely different in VOD, BCS, and CH; the similarities in clinical manifestations and liver histology may suggest a common mechanism of hepatic injury and adaptation in response to increased sinusoidal pressure.

  5. Protostellar outflows with Smoothed Particle Magnetohydrodynamics (SPMHD)

    CERN Document Server

    Bürzle, Florian; Stasyszyn, Federico; Dolag, Klaus; Klessen, Ralf S

    2011-01-01

    The protostellar collapse of a molecular cloud core is usually accompanied by outflow phenomena. The latter are thought to be driven by magnetorotational processes from the central parts of the protostellar disc. While several 3D AMR/nested grid studies of outflow phenomena in collapsing magnetically supercritical dense cores have been reported in the literature, so far no such simulation has been performed using the Smoothed Particle Hydrodynamics (SPH) method. This is mainly due to intrinsic numerical difficulties in handling magnetohydrodynamics within SPH, which only recently were partly resolved. In this work, we use an approach where we evolve the magnetic field via the induction equation, augmented with stability correction and divergence cleaning schemes. We consider the collapse of a rotating core of one solar mass, threaded by a weak magnetic field initially parallel to the rotation axis so that the core is magnetically supercritical. We show, that Smoothed Particle Magnetohydrodynamics (SPMHD) is a...

  6. The quasar-galaxy cross SDSS J1320+1644: A probable large-separation lensed quasar

    CERN Document Server

    Rusu, Cristian E; Iye, Masanori; Inada, Naohisa; Kayo, Issha; Shin, Min-Su; Sluse, Dominique; Strauss, Michael A

    2012-01-01

    We report the discovery of a pair of quasars at $z=1.487$, with a separation of $8\\farcs585\\pm0\\farcs002$. Subaru Telescope infrared imaging reveals the presence of an elliptical and a disk-like galaxy located almost symmetrically between the quasars, creating a cross-like configuration. Based on absorption lines in the quasar spectra and the colors of the galaxies, we estimate that both galaxies are located at redshift $z=0.899$. This, as well as the similarity of the quasar spectra, suggests that the system is a single quasar multiply imaged by a galaxy group or cluster acting as a gravitational lens, although the possibility of a binary quasar cannot be fully excluded. We show that the gravitational lensing hypothesis implies these galaxies are not isolated, but must be embedded in a dark matter halo of virial mass $\\sim 4 \\times 10^{14}\\ h_{70}^{-1}\\ {M}_\\odot$ assuming an NFW model with a concentration parameter of $c_{vir}=6$, or a singular isothermal sphere profile with a velocity dispersion of $\\sim 6...

  7. Towards a comprehensive picture of powerful quasars, their host galaxies and quasar winds at z ~ 0.5

    CERN Document Server

    Wylezalek, Dominika; Liu, Guilin; Obied, Georges

    2016-01-01

    Luminous type-2 quasars in which the glow from the central black hole is obscured by dust are ideal targets for studying their host galaxies and the quasars' effect on galaxy evolution. Such feedback appears ubiquitous in luminous obscured quasars where high velocity ionized nebulae have been found. We present rest-frame yellow-band (~5000 Angstroms) observations using the Hubble Space Telescope for a sample of 20 luminous quasar host galaxies at 0.2 < z < 0.6 selected from the Sloan Digital Sky Survey. For the first time, we combine host galaxy observations with geometric measurements of quasar illumination using blue-band HST observations and [OIII] integral field unit observations probing the quasar winds. The HST images reveal bright merger signatures in about half the galaxies; a significantly higher fraction than in comparison inactive ellipticals. We show that the host galaxies are primarily bulge-dominated, with masses close to M*, but belong to < 30% of elliptical galaxies that are highly st...

  8. SDSS quasars in the WISE preliminary data release and quasar candidate selection with the optical/infrared colors

    CERN Document Server

    Wu, Xue-Bing; Jia, Zhendong; Zhang, Yanxia; Peng, Nanbo

    2012-01-01

    We present a catalog of 37842 quasars in the Sloan Digital Sky Survey (SDSS) Data Release 7, which have counterparts within 6$"$ in the Wide-field Infrared Survey Explorer (WISE) Preliminary Data Release. The overall WISE detection rate of the SDSS quasars is 86.7%, and it decreases to less than 50.0% when the quasar magnitude is fainter than $i=20.5$. We derive the median color-redshift relations based on this SDSS-WISE quasar sample and apply them to estimate the photometric redshifts of the SDSS-WISE quasars. We find that by adding the WISE W1 and W2-band data to the SDSS photometry we can increase the photometric redshift reliability, defined as the percentage of sources with the photometric and spectroscopic redshift difference less than 0.2, from 70.3% to 77.2%. We also obtain the samples of WISE detected normal and late-type stars with SDSS spectroscopy, and present a criterion in the $z-W1$ vs. $g-z$ color-color diagram, $z-W1>0.66(g-z)+2.01$, to separate quasars from stars. With this criterion we can...

  9. A NEW MODEL FOR DARK MATTER HALOS HOSTING QUASARS

    Energy Technology Data Exchange (ETDEWEB)

    Cen, Renyue [Princeton University Observatory, Princeton, NJ 08544 (United States); Safarzadeh, Mohammadtaher, E-mail: cen@astro.princeton.edu [Johns Hopkins University, Department of Physics and Astronomy, Baltimore, MD 21218 (United States)

    2015-01-10

    A new model for quasar-hosting dark matter halos, meeting two physical conditions, is put forth. First, significant interactions are taken into consideration to trigger quasar activities. Second, satellites in very massive halos at low redshift are removed from consideration due to their deficiency in cold gas. We analyze the Millennium Simulation to find halos that meet these two conditions and simultaneously match two-point auto-correlation functions of quasars and cross-correlation functions between quasars and galaxies at z = 0.5-3.2. The masses of the quasar hosts found decrease with decreasing redshift, with the mass thresholds being [(2-5) × 10{sup 12}, (2-5) × 10{sup 11}, (1-3) × 10{sup 11}] M {sub ☉} for median luminosities of ∼[10{sup 46}, 10{sup 46}, 10{sup 45}] erg s{sup –1} at z = (3.2, 1.4, 0.53), respectively, an order of magnitude lower than those inferred based on halo occupation distribution modeling. In this model, quasar hosts are primarily massive central halos at z ≥ 2-3 but increasingly dominated by lower mass satellite halos experiencing major interactions toward lower redshift. However, below z = 1, satellite halos in groups more massive than ∼2 × 10{sup 13} M {sub ☉} do not host quasars. Whether for central or satellite halos, imposing the condition of significant interactions substantially boosts the clustering strength compared to the total population with the same mass cut. The inferred lifetimes of quasars at z = 0.5-3.2 of 3-30 Myr are in agreement with observations. Quasars at z ∼ 2 would be hosted by halos of mass ∼5 × 10{sup 11} M {sub ☉} in this model, compared to ∼3 × 10{sup 12} M {sub ☉} previously thought, which would help reconcile with the observed, otherwise puzzling high covering fractions for Lyman limit systems around quasars.

  10. DLA kinematics and outflows from starburst galaxies

    CERN Document Server

    Razoumov, Alexei O

    2008-01-01

    We present results from a numerical study of the multiphase interstellar medium in sub-Lyman-break galaxy protogalactic clumps. Such clumps are abundant at z=3 and are thought to be a major contributor to damped Ly-alpha absorption. We model the formation of winds from these clumps and show that during star formation episodes they feature outflows with neutral gas velocity widths up to several hundred km/s. Such outflows are consistent with the observed high-velocity dispersion in DLAs. In our models thermal energy feedback from winds and supernovae results in efficient outflows only when cold (~ 300 K), dense (> 100 msun/pc^3) clouds are resolved at grid resolution of 12 pc. At lower 24 pc resolution the first signs of the multiphase medium are spotted; however, at this low resolution thermal injection of feedback energy cannot yet create hot expanding bubbles around star-forming regions -- instead feedback tends to erase high-density peaks and suppress star formation. At 12 pc resolution feedback compresses...

  11. Hot Electromagnetic Outflows I: Acceleration and Spectra

    CERN Document Server

    Russo, Matthew

    2013-01-01

    The theory of cold, relativistic, magnetohydrodynamic outflows is generalized by the inclusion of an intense radiation source. In some contexts, such the breakout of a gamma-ray burst jet from a star, the outflow is heated to a high temperature at a large optical depth. Eventually it becomes transparent and is pushed to a higher Lorentz factor by a combination of the Lorentz force and radiation pressure. We obtain its profile, both inside and outside the fast magnetosonic critical point, when the poloidal magnetic field is radial and monopolar. Most of the energy flux is carried by the radiation field and the toroidal magnetic field that is wound up close to the rapidly rotating engine. Although the entrained matter carries little energy, it couples the radiation field to the magnetic field. Then the fast critical point is pushed inward from infinity and, above a critical radiation intensity, the outflow is accelerated mainly by radiation pressure. We identify a distinct observational signature of this hybrid...

  12. Magnotospheric imaging of high latitude ion outflows

    Directory of Open Access Journals (Sweden)

    D. E. Garrido

    Full Text Available High latitude ion outflows mostly consist of upward streaming O+ and He+ emanating from the ionosphere. At heights above 1000 km, these flows consist of cold and hot components which resonantly scatter solar extreme ultraviolet (EUV light, however, the ion populations respond differently to Doppler shifting resulting from the large relative velocities between the ions and the Sun. The possibility of optical detection of the Doppler effect on the scattering rate will be discussed for the O+ (83.4 nm ions. We have contrasted the EUV solar resonance images of these outflows by simulations of the 30.4 nm He+ and 83.4 nm O+ emissions for both quiet and disturbed geomagnetic conditions. Input data for the 1000 km level has been obtained from the EICS instrument aboard the Dynamics Explorer satellite. Our results show emission rates of 50 and 56 milli-Rayleighs at 30.4 nm for quiet and disturbed conditions and 65 and 75 milli-Rayleighs at 83.4 nm for quiet and disturbed conditions, respectively, obtained for a polar orbiting satellite and viewing radially outward. We also find that an imager at an equatorial distance of 9 RE or more is in a favourable position for detecting ion outflows, particularly when the plasmapause is depressed in latitude. However, an occultation disk is necessary to obscure the bright plasmaspheric emissions.

  13. A Robust Measurement of the Mass Outflow Rate of the Galactic Outflow from NGC 6090

    CERN Document Server

    Chisholm, John; Leitherer, Claus; Chen, Yanmei

    2016-01-01

    To evaluate the impact of stellar feedback, it is critical to estimate the mass outflow rates of galaxies. Past estimates have been plagued by uncertain assumptions about the outflow geometry, metallicity, and ionization fraction. Here we use Hubble Space Telescope ultraviolet spectroscopic observations of the nearby starburst NGC 6090 to demonstrate that many of these quantities can be constrained by the data. We use the Si~{\\sc IV} absorption lines to calculate the scaling of velocity (v), covering fraction (C$_f$), and density with distance from the starburst (r), assuming the Sobolev optical depth and a velocity law of the form: $v \\propto(1 -R_i/r )^\\beta$ (were R$_i$ is the inner outflow radius). We find that the velocity ($\\beta$=0.43) is consistent with an outflow driven by an r$^{-2}$ force, while the scaling of the covering fraction ($C_f \\propto r^{-0.82}$) suggests that cool clouds in the outflow are in pressure equilibrium with an adiabatically expanding medium. We use the column densities of fou...

  14. A NEOWISE Survey of Quasars in the Epoch of Reionization

    Science.gov (United States)

    Fan, Xiaohui

    Luminous quasars at high redshift provide direct probes of the evolution of supermassive black holes (BHs) and intergalactic medium (IGM) at early cosmic time. More than 100 quasars have now been discovered at z>6, with the highest redshift at z=7.1. Detections of such objects indicate the existence of billion solar mass BHs merely a few hundred Myrs after the first star formation in the universe, challenging the theory of BH growth and BH-galaxy coevolution at early epoch. Absorption spectra of the highest redshift quasars reveal complete Gunn-Peterson absorption from an increasing neutral IGM, marking the end of the reionization epoch at z>6. Combined with observations of CMB polarization and high-redshift Ly alpha galaxies, current data strongly suggest a peak of reionization activity and emergence of the earliest galaxies and AGNs at 77, and a handful at z>6.5. In this ADAP program, we will carry out the first comprehensive survey of z>=7 quasars, using a WISE-based selection algorithm, deep mid-IR photometry from coadded NEOWISE data and deep optical and near-IR photometry from new wide-field imaging surveys. We will select and follow-up quasar candidates over >20,000 deg^2 of high galactic latitude sky, aiming at finding 10-15 quasars at z>=7 in the next three years. There are two main technical components of our program. (1) WISE-based quasar selection. We have developed a highly successful selection method by combining WISE and optical/near-IR photometry to search for luminous quasars at z = 4.5-6.5, resulted in the discovery of the first known supermassive black holes with 10 billion solar mass BHs in the early universe. We will expand and optimize the algorithm for the redshift range of 6.5 measure the density of luminous quasars and their BH masses at z>=7, and place constraint on the existence of z>8 quasars. These measurements will test whether super-Eddington accretion or direct formation of intermediate-mass BHs are needed for early BH growth

  15. Paleoceanography. Onset of Mediterranean outflow into the North Atlantic.

    Science.gov (United States)

    Hernández-Molina, F Javier; Stow, Dorrik A V; Alvarez-Zarikian, Carlos A; Acton, Gary; Bahr, André; Balestra, Barbara; Ducassou, Emmanuelle; Flood, Roger; Flores, José-Abel; Furota, Satoshi; Grunert, Patrick; Hodell, David; Jimenez-Espejo, Francisco; Kim, Jin Kyoung; Krissek, Lawrence; Kuroda, Junichiro; Li, Baohua; Llave, Estefania; Lofi, Johanna; Lourens, Lucas; Miller, Madeline; Nanayama, Futoshi; Nishida, Naohisa; Richter, Carl; Roque, Cristina; Pereira, Hélder; Sanchez Goñi, Maria Fernanda; Sierro, Francisco J; Singh, Arun Deo; Sloss, Craig; Takashimizu, Yasuhiro; Tzanova, Alexandrina; Voelker, Antje; Williams, Trevor; Xuan, Chuang

    2014-06-13

    Sediments cored along the southwestern Iberian margin during Integrated Ocean Drilling Program Expedition 339 provide constraints on Mediterranean Outflow Water (MOW) circulation patterns from the Pliocene epoch to the present day. After the Strait of Gibraltar opened (5.33 million years ago), a limited volume of MOW entered the Atlantic. Depositional hiatuses indicate erosion by bottom currents related to higher volumes of MOW circulating into the North Atlantic, beginning in the late Pliocene. The hiatuses coincide with regional tectonic events and changes in global thermohaline circulation (THC). This suggests that MOW influenced Atlantic Meridional Overturning Circulation (AMOC), THC, and climatic shifts by contributing a component of warm, saline water to northern latitudes while in turn being influenced by plate tectonics.

  16. A Wealth of Dust Grains in Quasar Winds

    Science.gov (United States)

    2007-01-01

    [figure removed for brevity, see original site] Click on image for larger poster version This plot of data captured by NASA's Spitzer Space Telescope reveals dust entrained in the winds rushing away from a quasar, or growing black hole. The quasar, called PG2112+059, is located deep inside a galaxy 8 billion light-years away. Astronomers believe the dust might have been forged in the winds, which would help explain where dust in the very early universe came from. The data were captured by Spitzer's infrared spectrograph, an instrument that splits apart light from the quasar into a spectrum that reveals telltale signs of different minerals. Each type of mineral, or dust grain, has a unique signature, as can be seen in the graph, or spectrum, above. The strongest features are from the mineral amorphous olivine, or glass (purple); the mineral forsterite found in sand (blue); and the mineral corundum found in rubies (light blue). The detection of forsterite and corundum is highly unusual in galaxies without quasars. Therefore, their presence is a key clue that these grains might have been created in the quasar winds and not by dying stars as they are in our Milky Way galaxy. Forsterite is destroyed quickly in normal galaxies by radiation, so it must be continually produced to be detected by Spitzer. Corundum is hard, and provides a seed that softer, more common minerals usually cover up. As a result, corundum is usually not seen in spectra of galaxies. Since Spitzer did detect the mineral, it is probably forming in a clumpy environment, which is expected in quasar winds. All together, the signatures of the unusual minerals in this spectrum point towards dust grains forming in the winds blowing away from quasars.

  17. Microlensing Constraints on Broad Absorption and Emission Line Flows in the Quasar H1413+117

    CERN Document Server

    O'Dowd, Matthew J; Webster, Rachel L; Labrie, Kathleen; Rogers, Joshua

    2015-01-01

    We present new integral field spectroscopy of the gravitationally lensed broad absorption line (BAL) quasar H1413+117, covering the ultraviolet to visible rest-frame spectral range. We observe strong microlensing signatures in lensed image D, and we use this microlensing to simultaneously constrain both the broad emission and broad absorption line gas. By modeling the lens system over the range of probable lensing galaxy redshifts and using on a new argument based on the wavelength-independence of the broad line lensing magnifications, we determine that there is no significant broad line emission from smaller than ~20 light days. We also perform spectral decomposition to derive the intrinsic broad emission line (BEL) and continuum spectrum, subject to BAL absorption. We also reconstruct the intrinsic BAL absorption profile, whose features allow us to constrain outflow kinematics in the context of a disk-wind model. We find a very sharp, blueshifted onset of absorption of 1,500 km/s in both C IV and N V that m...

  18. Chandra LETGS spectroscopy of the Quasar MR2251-178 and its warm absorber

    CERN Document Server

    Ramírez, J M; Burwitz, V; Mathur, S

    2008-01-01

    We present an analysis of our Chandra Low Energy Transmission Grating Spectrometer (LETGS) observation of the quasar MR2251-178. The warm absorber of MR2251-178 is well described by a hydrogen column density, N_H~2x10^21 cm^-2, and an ionization parameter log(xi)~0.6. We find in the spectrum weak evidence for narrow absorption lines from Carbon and Nitrogen which indicate that the ionized material is in outflow. We note changes (in time) of the absorption structure in the band (0.6-1) keV (around the UTAs plus the OVII and OVIII K-edges) at different periods of the observation. We measure a (0.1-2) keV flux of 2.58x10^-11 ergs cm^-2 s^-1. This flux implies that the nuclear source of MR2251-178 is in a relatively low state. No significant variability is seen in the light curve. We find evidence for an extra cold material in the line of sight, and set an upper limit of N_H~1.2x10^20 cm^-2. The X-ray spectrum does not appear to show evidence for dusty material, though an upper limit in the neutral carbon and oxy...

  19. Fifty Years of Quasars From Early Observations and Ideas to Future Research

    CERN Document Server

    Marziani, Paola; Sulentic, Jack

    2012-01-01

    The 50th anniversary of the discovery of quasars in 1963 presents an interesting opportunity to ask questions about the current state of quasar research. Formatted as a series of interviews with noted researchers in the field, each of them asked to address a specific set of questions covering topics selected by the editors, this book deals with the historical development of quasar research and discusses how advances in instrumentation and computational capabilities have benefitted quasar astronomy and have changed our basic understanding of quasars. In the last part of the book the interviews address the current topic of the role of quasars in galaxy evolution. They summarise open issues in understanding active galactic nuclei and quasars and present an outlook regarding what future observational facilities both on the ground and in space might reveal. Its interview format, the fascinating topic of quasars and black holes, and the lively recollections and at times controversial views of the contributors make ...

  20. The Prevalence of Gas Outflows in Type 2 AGNs. II. 3D Biconical Outflow Models

    Science.gov (United States)

    Bae, Hyun-Jin; Woo, Jong-Hak

    2016-09-01

    We present 3D models of biconical outflows combined with a thin dust plane for investigating the physical properties of the ionized gas outflows and their effect on the observed gas kinematics in type 2 active galactic nuclei (AGNs). Using a set of input parameters, we construct a number of models in 3D and calculate the spatially integrated velocity and velocity dispersion for each model. We find that three primary parameters, i.e., intrinsic velocity, bicone inclination, and the amount of dust extinction, mainly determine the simulated velocity and velocity dispersion. Velocity dispersion increases as the intrinsic velocity or the bicone inclination increases, while velocity (i.e., velocity shifts with respect to systemic velocity) increases as the amount of dust extinction increases. Simulated emission-line profiles well reproduce the observed [O iii] line profiles, e.g., narrow core and broad wing components. By comparing model grids and Monte Carlo simulations with the observed [O iii] velocity-velocity dispersion distribution of ˜39,000 type 2 AGNs, we constrain the intrinsic velocity of gas outflows ranging from ˜500 to ˜1000 km s-1 for the majority of AGNs, and up to ˜1500-2000 km s-1 for extreme cases. The Monte Carlo simulations show that the number ratio of AGNs with negative [O iii] velocity to AGNs with positive [O iii] velocity correlates with the outflow opening angle, suggesting that outflows with higher intrinsic velocity tend to have wider opening angles. These results demonstrate the potential of our 3D models for studying the physical properties of gas outflows, applicable to various observations, including spatially integrated and resolved gas kinematics.

  1. An infrared view of AGN feedback in a type-2 quasar: the case of the Teacup galaxy

    Science.gov (United States)

    Ramos Almeida, C.; Piqueras López, J.; Villar-Martín, M.; Bessiere, P. S.

    2017-09-01

    We present near-infrared integral field spectroscopy data obtained with Very Large Telescope/Spectrograph for INtegral Field Observations in the Near Infrared (SINFONI) of 'the Teacup galaxy'. The nuclear K-band (1.95-2.45 μm) spectrum of this radio-quiet type-2 quasar reveals a blueshifted broad component of FWHM ∼ 1600-1800 km s-1 in the hydrogen recombination lines (Pa α, Br δ and Br γ) and also in the coronal line [Si vi] λ1.963 μm. Thus, the data confirm the presence of the nuclear ionized outflow previously detected in the optical range and reveal its coronal counterpart. Both the ionized and coronal nuclear outflows are resolved, with seeing-deconvolved full widths at half-maximum of 1.1 ± 0.1 and 0.9 ± 0.1 kpc along position angle (PA) ∼ 72°-74°. This orientation is almost coincident with the radio axis (PA = 77°), suggesting that the radio jet could have triggered the nuclear outflow. In the case of the H2 lines, we do not require a broad component to reproduce the profiles, but the narrow lines are blueshifted by ∼50 km s-1 on average from the galaxy systemic velocity. This could be an indication of the presence of a nuclear molecular outflow, although the bulk of the H2 emission in the inner ∼2 arcsec (∼3 kpc) of the galaxy follows a rotation pattern. We find evidence for kinematically disrupted gas (FWHM > 250 km s-1) at up to 5.6 kpc from the AGN, which can be naturally explained by the action of the outflow. The narrow component of [Si vi] is redshifted with respect to the systemic velocity, unlike any other emission line in the K-band spectrum. This indicates that the region where the coronal lines are produced is not cospatial with the narrow-line region.

  2. Structure of radiation dominated gravitoturbulent quasar discs

    CERN Document Server

    Shadmehri, Mohsen; Dib, Sami

    2016-01-01

    Self-gravitating accretion discs in a gravitoturbulent state, including radiation and gas pressures, are studied using a set of new analytical solutions. While the Toomre parameter of the disc remains close to its critical value for the onset of gravitational instability, the dimensionless stress parameter is uniquely determined from the thermal energy reservoir of the disc and its cooling rate. Our solutions are applicable to the accretion discs with dynamically important radiation pressure like in the quasars discs. We show that physical quantities of a gravitoturbulent disc in the presence of radiation are significantly modified compared to solutions with only gas pressure. We show that the dimensionless stress parameter is an increasing function of the radial distance so that its steepness strongly depends on the accretion rate. In a disc without radiation its slope is 4.5, however, we show that in the presence of radiation, it varies between 2 and 4.5 depending on the accretion rate and the central mass....

  3. Are quasar jets dominated by Poynting flux?

    CERN Document Server

    Sikora, M; Madejski, G M; Lasota, J P; Sikora, Marek; Begelman, Mitchell C.; Madejski, Greg M.; Lasota, Jean-Pierre

    2005-01-01

    The formation of relativistic astrophysical jets is presumably mediated by magnetic fields threading accretion disks and central, rapidly rotating objects. As it is accelerated by magnetic stresses, the jet's kinetic energy flux grows at the expense of its Poynting flux. However, it is unclear how efficient is the conversion from magnetic to kinetic energy and whether there are any observational signatures of this process. We address this issue in the context of jets in quasars. Using data from all spatial scales, we demonstrate that in these objects the conversion from Poynting-flux-dominated to matter-dominated jets is very likely to take place closer to the black hole than the region where most of the Doppler boosted radiation observed in blazars is produced. We briefly discuss the possibility that blazar activity can be induced by global MHD instabilities, e.g., via the production of localized velocity gradients that lead to dissipative events such as shocks or magnetic reconnection, where acceleration of...

  4. Quasar Variability in the Mid-Infrared

    CERN Document Server

    Kozlowski, Szymon; Ashby, Matthew L N; Assef, Roberto J; Brodwin, Mark; Eisenhardt, Peter R; Jannuzi, Buell T; Stern, Daniel

    2015-01-01

    The Decadal IRAC Bootes Survey (DIBS) is a mid-IR variability survey of the ~9 sq. deg. of the NDWFS Bootes Field and extnds the time baseline of its predecessor, the Spitzer Deep, Wide-Field Survey (SDWFS), from 4 to 10 years. The Spitzer Space Telescope visited the field five times between 2004 and 2014 at 3.6 and 4.5 microns. We provide the difference image analysis photometry for a half a million mostly extragalactic sources. In the mid-IR color-color plane, sources with quasar colors constitute the largest variability class (75%), 16% of the variable objects have stellar colors and the remaining 9% have the colors of galaxies. Adding the fifth epoch doubles the number of variable AGNs for the same false positive rates as in SDWFS, or increases the number of sources by 20% while decreasing the false positive rates by factors of 2-3 for the same variability amplitude. We quantify the ensemble mid-IR variability of ~1500 spectroscopically confirmed AGNs using single power-law structure functions, which we f...

  5. How fast black holes spin in quasars

    CERN Document Server

    Maio, Umberto; Petkova, Margarita; Perego, Albino; Volonteri, Marta

    2012-01-01

    Mass and spin are often referred to as the two `hairs' of astrophysical black holes, as they are the only two parameters needed to completely characterize them in General Relativity. The interaction between black holes and their environment is where complexity lies, as the relevant physical processes occur over a large range of scales. This is particularly relevant in the case of super-massive black holes (SMBHs), hosted in galaxy centers and surrounded by swirling gas and various generations of stars, that compete with the SMBH for gas consumption, and affect the thermodynamics of the gas itself. How dynamics and thermodynamics in such fiery environment affect the angular momentum of the gas accreted onto SMBHs, and hence black hole spins is uncertain. We explore the interaction between SMBHs and their environment during active phases through simulations of circum-nuclear discs (CND) around black holes in quasars hosted in the remnants of galaxy mergers. These are the first 3D (sub-)parsec resolution simulat...

  6. Are Quasar Jets Dominated by Poynting Flux?

    Energy Technology Data Exchange (ETDEWEB)

    Sikora, M

    2005-02-02

    The formation of relativistic astrophysical jets is presumably mediated by magnetic fields threading accretion disks and central, rapidly rotating objects. As it is accelerated by magnetic stresses, the jet's kinetic energy flux grows at the expense of its Poynting flux. However, it is unclear how efficient is the conversion from magnetic to kinetic energy and whether there are any observational signatures of this process. We address this issue in the context of jets in quasars. Using data from all spatial scales, we demonstrate that in these objects the conversion from Poynting-flux-dominated to matter-dominated jets is very likely to take place closer to the black hole than the region where most of the Doppler boosted radiation observed in blazars is produced. We briefly discuss the possibility that blazar activity can be induced by global MHD instabilities, e.g., via the production of localized velocity gradients that lead to dissipative events such as shocks or magnetic reconnection, where acceleration of relativistic particles and production of non-thermal flares is taking place.

  7. A portable modeler of lensed quasars

    CERN Document Server

    Saha, P; Saha, Prasenjit; Williams, Liliya L.R.

    2004-01-01

    We introduce and implement two novel ideas for modeling lensed quasars. The first idea is to require different lenses to agree about H_0. This means that some models for one lens can be ruled out by data on a different lens. We explain using two worked examples. One example models 1115+080, 1608+656 (time-delay quads) and 1933+503 (a prospective time-delay system) all together, yielding time-delay predictions for the third lens and a 90%-confidence estimate of 1/H_0=14.6_{-1.7}^{+9.4} Gyr (H_0=67_{-26}^{+9} km/s/Mpc) assuming Omega_M=0.3, Omega_Lambda=0.7. The other example models the time-delay doubles 1520+530, 1600+434, 1830-211, and 2149-275, which gives 1/H_0=14.5_{-1.5}^{+3.3} Gyr (H_0=67_{-13}^{+8} km/s/Mpc). Our second idea is to write the whole modeling software as a highly interactive Java applet, which can be used both for coarse-grained results inside a browser and for fine-grained results on a workstation. Several obstacles come up in trying to implement a numerically-intensive method thus, but w...

  8. Clusters of galaxies associated with quasars. I. 3C 206

    Energy Technology Data Exchange (ETDEWEB)

    Ellingson, E.; Yee, H.K.C.; Green, R.F.; Kinman, T.D. (Steward Observatory, Tucson, AZ (USA); Montreal Universite (Canada); Kitt Peak National Observatory, Tucson, AZ (USA))

    1989-06-01

    Multislit spectroscopy and three-color CCD photometry of the galaxies in the cluster associated with the quasar 3C 206 (PKS 0837-12) at z = 0.198 are presented. This cluster is the richest environment of any low-redshift quasar observed in an Abell richness class 1 cluster. The cluster has a very flattened structure and a very concentrated core about the quasar. Most of the galaxies in this field have colors and luminosities consistent with normal galaxies at this redshift. The background-corrected blue fraction of galaxies is consistent with values for other rich clusters. The existence of several blue galaxies in the concentrated cluster core is an anomaly for a region of such high galaxy density, however, suggesting the absence of a substantial intracluster medium. This claim is supported by the Fanaroff-Riley (1974) class II morphology of the radio source. The velocity dispersion calculated from 11 spectroscopically confirmed cluster members is 500 + or - 110 km/s, which is slightly lower than the average for Abell class 1 clusters. A high frequency of interaction between the quasar host galaxy and cluster core members at low relative velocities, and a low intracluster gas pressure, may comprise a favorable environment for quasar activity. The properties of the cluster of galaxies associated with 3C 206 are consistent with this model. 59 refs.

  9. HST/COS OBSERVATIONS OF THIRTEEN NEW He II QUASARS

    Energy Technology Data Exchange (ETDEWEB)

    Syphers, David [CASA, Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, CO 80309 (United States); Anderson, Scott F. [Department of Astronomy, University of Washington, Seattle, WA 98195 (United States); Zheng Wei [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States); Meiksin, Avery [Scottish Universities Physics Alliance (SUPA), Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh EH9 3HJ (United Kingdom); Schneider, Donald P. [Department of Physics and Astronomy, Pennsylvania State University, University Park, PA 16802 (United States); York, Donald G., E-mail: David.Syphers@colorado.edu [Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637 (United States)

    2012-04-15

    The full reionization of intergalactic helium was a major event in the history of the intergalactic medium (IGM), and UV observations of the He II Gunn-Peterson trough allow us to characterize the end of this process at z {approx} 3. Due to intervening hydrogen absorption, quasars allowing such study are rare, with only 33 known in the literature, and most of those are very recent discoveries. We expand on our previous discovery work, and present 13 new He II quasars with redshifts 2.82 < z < 3.77, here selected with {approx}80% efficiency, and including several that are much brighter than the vast majority of those previously known. This is the largest sample of uniformly observed He II quasars covering such a broad redshift range, and they show evidence of IGM opacity increasing with redshift, as expected for the helium reionization epoch. No evidence of He II Ly{alpha} quasar emission is seen in individual or averaged spectra, posing a problem for standard models of the broad-line region. The current rapid advance in the study of He II quasars has been greatly facilitated by the Cosmic Origins Spectrograph on the Hubble Space Telescope, and we discuss the instrumental and other subtleties that must be taken into account in IGM He II observations.

  10. Photometric Classification of quasars from RCS-2 using Random Forest

    CERN Document Server

    Carrasco, D; Pichara, K; Anguita, T; Murphy, D N A; Gilbank, D G; Gladders, M D; Yee, H K C; Hsieh, B C; López, S

    2014-01-01

    We describe the construction of a quasar catalog containing 91,842 candidates derived from analysis of imaging data with a Random Forest algorithm. Using spectroscopically-confirmed stars and quasars from the SDSS as a training set, we blindly search the RCS-2 (~750 deg^2) imaging survey. From a source catalogue of 1,863,970 RCS-2 point sources, our algorithm identifies putative quasars from broadband magnitudes (g, r, i, z) and colours. Exploiting NUV GALEX measurements available for a subset 16,898 of these objects, we refine the classifier by adding NUV-optical colours to the algorithm's search. An additional subset (comprising 13% of the source catalog) features WISE coverage; we explore the effect of including W1 and W2 bands on the performance of the algorithm. Upon analysing all RCS-2 point sources, the algorithm identified 85,085 quasar candidates, with a training-set-derived precision (the fraction of true positives within the group assigned quasar status) of 90.4% and a recall (the fraction of true ...

  11. Thermal Emission from Warm Dust in the Most Distant Quasars

    CERN Document Server

    Wang, R; Wagg, J; Bertoldi, F; Walter, F; Menten, K M; Omont, A; Cox, P; Strauss, M A; Fan, X; Jiang, L; Schneider, D P

    2008-01-01

    We report new continuum observations of fourteen z~6 quasars at 250 GHz and fourteen quasars at 1.4 GHz. We summarize all recent millimeter and radio observations of the sample of the thirty-three quasars known with 5.7110^{12}L_{\\odot}), while the average L_{FIR}/L_{bol} ratio of the non-detections is consistent with that of the optically-selected PG quasars. The MAMBO detections also tend to have weaker Ly\\alpha emission than the non-detected sources. We discuss possible FIR dust heating sources, and critically assess the possibility of active star formation in the host galaxies of the z~6 quasars. The average star formation rate of the MAMBO non-detections is likely to be less than a few hundred M_{\\odot} yr^{-1}, but in the strong detections, the host galaxy star formation is probably at a rate of \\gtrsim10^{3} M_{\\odot} yr^{-1}, which dominates the FIR dust heating.

  12. Dissecting the complex environment of a distant quasar with MUSE

    CERN Document Server

    Husband, K; Stanway, E R; Lehnert, M D

    2015-01-01

    High redshift quasars can be used to trace the early growth of massive galaxies and may be triggered by galaxy-galaxy interactions. We present MUSE science verification data on one such interacting system consisting of the well-studied z=3.2 PKS1614+051 quasar, its AGN companion galaxy and bridge of material radiating in Lyalpha between the quasar and its companion. We find a total of four companion galaxies (at least two galaxies are new discoveries), three of which reside within the likely virial radius of the quasar host, suggesting that the system will evolve into a massive elliptical galaxy by the present day. The MUSE data are of sufficient quality to split the extended Lyalpha emission line into narrow velocity channels. In these the gas can be seen extending towards each of the three neighbouring galaxies suggesting that the emission-line gas originates in a gravitational interaction between the galaxies and the quasar host. The photoionization source of this gas is less clear but is probably dominate...

  13. Dissecting the quasar main sequence: insight from host galaxy properties

    CERN Document Server

    Sun, Jiayi

    2015-01-01

    The diverse properties of broad-line quasars appear to follow a well-defined main sequence along which the optical FeII strength increases. It has been suggested that this sequence is mainly driven by the Eddington ratio (L/L_Edd) of the black hole (BH) accretion. Shen & Ho demonstrated with quasar clustering analysis that the average BH mass decreases with increasing FeII strength when quasar luminosity is fixed, consistent with this suggestion. Here we perform an independent test by measuring the stellar velocity dispersion sigma* (hence the BH mass via the M-sigma* relation) from decomposed host spectra in low-redshift Sloan Digital Sky Survey quasars. We found that at fixed quasar luminosity, sigma* systematically decreases with increasing FeII strength, confirming that Eddington ratio increases with FeII strength. We also found that at fixed luminosity and FeII strength, there is little dependence of sigma* on the broad Hbeta FWHM. These new results reinforce the framework put forward by Shen & H...

  14. He II Proximity Effect and the Lifetime of Quasars

    CERN Document Server

    Khrykin, I S; McQuinn, M; Worseck, G

    2015-01-01

    The lifetime of quasars is fundamental for understanding the growth of supermassive black holes, and is an important ingredient in models of the reionization of the intergalactic medium. However, despite various attempts to determine quasar lifetimes, current estimates from a variety of methods are uncertain by orders of magnitude. This work combines cosmological hydrodynamical simulations and 1D radiative transfer to investigate the structure and evolution of the He II Ly$\\alpha$ proximity zones around quasars at $z \\simeq 3-4$. We show that the time evolution in the proximity zone can be described by a simple analytical model for the approach of the He II fraction $x_{\\rm HeII}\\left( t \\right)$ to ionization equilibrium, and use this picture to illustrate how the transmission profile depends on the quasar lifetime, quasar UV luminosity, and the ionization state of helium in the ambient IGM (i.e. the average He II fraction, or equivalently the metagalactic He II ionizing background). A significant degeneracy...

  15. Mass Functions of the Active Black Holes in Distant Quasars from the Large Bright Quasar Survey, the Bright Quasar Survey, and the Color-Selected Sample of the SDSS Fall Equatorial Stripe

    DEFF Research Database (Denmark)

    Vestergaard, Marianne; Osmer, Patrick S.

    2009-01-01

    We present mass functions of distant actively accreting supermassive black holes residing in luminous quasars discovered in the Large Bright Quasar Survey, the Bright Quasar Survey, and the Fall Equatorial Stripe of the Sloan Digital Sky Survey (SDSS). The quasars cover a wide range of redshifts (0...... functions at similar redshifts based on the SDSS Data Release 3 quasar catalog presented by Vestergaard et al. We see clear evidence of cosmic downsizing in the comoving space density distribution of active black holes in the LBQS sample alone. In forthcoming papers, further analysis, comparison......, and discussion of these mass functions will be made with other existing black hole mass functions, notably that based on the SDSS DR3 quasar catalog. We present the relationships used to estimate the black hole mass based on the MgII emission line; the relations are calibrated to the Hbeta and CIV relations...

  16. An Apparent Redshift Dependence of Quasar Continuum: Implication for Cosmic Dust Extinction?

    CERN Document Server

    Xie, Xiaoyi; Shao, Zhengyi; Yin, Jun

    2015-01-01

    We investigate the luminosity and redshift dependence of the quasar continuum by means of composite spectrum using a large non-BAL radio-quiet quasar sample drawn from the Sloan Digital Sky Survey. Quasar continuum slopes in the UV-Opt band are measured at two different wavelength ranges, i.e., $\\alpha_{\

  17. Quasars Probing Quasars VII. The Pinnacle of the Cool Circumgalactic Medium Surrounds Massive z~2 Galaxies

    CERN Document Server

    Prochaska, J Xavier; Hennawi, Joseph F

    2014-01-01

    We survey the incidence and absorption strength of the metal-line transitions CII 1334 and CIV from the circumgalactic medium (CGM) surrounding z~2 quasars, which act as signposts for massive dark matter halos M_halo~10^12.5 Msun. On scales of the virial radius (Mvir~160kpc), we measure a high covering fraction fC=0.73+/-0.10 to strong CII absorption (rest equivalent width W1334>0.2A), implying a massive reservoir of cool (T~10^4K) metal enriched gas. We conservatively estimate a metal mass exceeding 10^8 Msun. We propose these metals trace enrichment of the incipient intragroup/intracluster medium that these halos eventually inhabit. This cool CGM around quasars is the pinnacle amongst galaxies observed at all epochs, as regards covering fraction and average equivalent width of HI Lya and low-ion metal absorption. We argue that the properties of this cool CGM primarily reflect the halo mass, and that other factors such as feedback, star-formation rate, and accretion from the intergalactic medium are secondar...

  18. The Wide-Angle Outflow of the Lensed z = 1.51 AGN HS 0810+2554

    CERN Document Server

    Chartas, G; Hamann, F; Eracleous, M; Strickland, S; Giustini, M; Misawa, T

    2016-01-01

    We present results from X-ray observations of the gravitationally lensed z = 1.51 AGN HS 0810+2554 performed with the Chandra X-ray Observatory and XMM-Newton. Blueshifted absorption lines are detected in both observations at rest-frame energies ranging between ~1-12 keV at > 99% confidence. The inferred velocities of the outflowing components range between ~0.1c and ~0.4c. A strong emission line at ~6.8 keV accompanied by a significant absorption line at ~7.8 keV is also detected in the Chandra observation. The presence of these lines is a characteristic feature of a P-Cygni profile supporting the presence of an expanding outflowing highly ionized iron absorber in this quasar. Modeling of the P-Cygni profile constrains the covering factor of the wind to be > 0.6, assuming disk shielding. A disk-reflection component is detected in the XMM-Newton observation accompanied by blueshifted absorption lines. The XMM-Newton observation constrains the inclination angle to be < 45 degrees at 90% confidence, assuming...

  19. A resolved outflow of matter from a Brown Dwarf

    CERN Document Server

    Whelan, E T; Bacciotti, F; Natta, A; Testi, L; Randich, S; Whelan, Emma T.; Ray, Thomas P.; Bacciotti, Francesca; Natta, Antonella; Testi, Leonardo; Randich, Sofia

    2005-01-01

    The birth of stars involves not only accretion but also, counter-intuitively, the expulsion of matter in the form of highly supersonic outflows. Although this phenomenon has been seen in young stars, a fundamental question is whether it also occurs amongst newborn brown dwarfs: these are the so-called 'failed stars', with masses between stars and planets, that never manage to reach temperatures high enough for normal hydrogen fusion to occur. Recently, evidence for accretion in young brown dwarfs has mounted, and their spectra show lines that are suggestive of outflows. Here we report spectro-astrometric data that spatially resolve an outflow from a brown dwarf. The outflow's characteristics appear similar to, but on a smaller scale than, outflows from normal young stars. This result suggests that the outflow mechanism is universal, and perhaps relevant even to the formation of planets.

  20. A resolved outflow of matter from a brown dwarf.

    Science.gov (United States)

    Whelan, Emma T; Ray, Thomas P; Bacciotti, Francesca; Natta, Antonella; Testi, Leonardo; Randich, Sofia

    2005-06-01

    The birth of stars involves not only accretion but also, counter-intuitively, the expulsion of matter in the form of highly supersonic outflows. Although this phenomenon has been seen in young stars, a fundamental question is whether it also occurs among newborn brown dwarfs: these are the so-called 'failed stars', with masses between stars and planets, that never manage to reach temperatures high enough for normal hydrogen fusion to occur. Recently, evidence for accretion in young brown dwarfs has mounted, and their spectra show lines that are suggestive of outflows. Here we report spectro-astrometric data that spatially resolve an outflow from a brown dwarf. The outflow's characteristics appear similar to, but on a smaller scale than, outflows from normal young stars. This result suggests that the outflow mechanism is universal, and perhaps relevant even to the formation of planets.

  1. Interferometric Mapping of Perseus Outflows with MASSES

    Science.gov (United States)

    Stephens, Ian; Dunham, Michael; Myers, Philip C.; MASSES Team

    2017-01-01

    The MASSES (Mass Assembly of Stellar Systems and their Evolution with the SMA) survey, a Submillimeter Array (SMA) large-scale program, is mapping molecular lines and continuum emission about the 75 known Class 0/I sources in the Perseus Molecular Cloud. In this talk, I present some of the key results of this project, with a focus on the CO(2-1) maps of the molecular outflows. In particular, I investigate how protostars inherit their rotation axes from large-scale magnetic fields and filamentary structure.

  2. Functional Anatomy of the Outflow Facilities.

    Science.gov (United States)

    Pizzirani, Stefano; Gong, Haiyan

    2015-11-01

    In order to understand the pathophysiology, select optimal therapeutic options for patients and provide clients with honest expectations for cases of canine glaucoma, clinicians should be familiar with a rational understanding of the functional anatomy of the ocular structures involved in this group of diseases. The topographical extension and the structural and humoral complexity of the regions involved with the production and the outflow of aqueous humor undergo numerous changes with aging and disease. Therefore, the anatomy relative to the fluid dynamics of aqueous has become a pivotal yet flexible concept to interpret the different phenotypes of glaucoma.

  3. ATOMIC HYDROGEN IN A GALACTIC CENTER OUTFLOW

    Energy Technology Data Exchange (ETDEWEB)

    McClure-Griffiths, N. M.; Green, J. A.; Hill, A. S. [Australia Telescope National Facility, CSIRO Astronomy and Space Science, Marsfield, NSW 2122 (Australia); Lockman, F. J. [National Radio Astronomy Observatory, Green Bank, WV 24944 (United States); Dickey, J. M. [School of Physics and Mathematics, University of Tasmania, TAS 7001 (Australia); Gaensler, B. M.; Green, A. J., E-mail: naomi.mcclure-griffiths@csiro.au [Sydney Institute for Astronomy, School of Physics, The University of Sydney, NSW 2006 (Australia)

    2013-06-10

    We describe a population of small, high-velocity, atomic hydrogen clouds, loops, and filaments found above and below the disk near the Galactic center. The objects have a mean radius of 15 pc, velocity widths of {approx}14 km s{sup -1}, and are observed at |z| heights up to 700 pc. The velocity distribution of the clouds shows no signature of Galactic rotation. We propose a scenario where the clouds are associated with an outflow from a central star-forming region at the Galactic center. We discuss the clouds as entrained material traveling at {approx}200 km s{sup -1} in a Galactic wind.

  4. Outflows vs. Clouds in AGN Intrinsic Absorbers

    OpenAIRE

    Arav, Nahum

    2003-01-01

    We discuss the crucial role of a dynamical picture in the analysis of AGN intrinsic absorbers data. High quality FUSE data of Mrk 279 are used to demonstrate that the line of sight covering fraction is a strong function of velocity. In Mrk 279, as well as in most cases where the data is of high enough quality, the shape of the absorption troughs is mainly determined by the velocity-dependent covering fraction. We argue that the traditional ``cloud'' picture of AGN outflows is hard pressed to ...

  5. Radiation hydrodynamic simulations of line-driven disk winds for ultra-fast outflows

    Science.gov (United States)

    Nomura, Mariko; Ohsuga, Ken; Takahashi, Hiroyuki R.; Wada, Keiichi; Yoshida, Tessei

    2016-02-01

    Using two-dimensional radiation hydrodynamic simulations, we investigate the origin of the ultra-fast outflows (UFOs) that are often observed in luminous active galactic nuclei (AGNs). We found that the radiation force due to the spectral lines generates strong winds (line-driven disk winds) that are launched from the inner region of accretion disks (˜30 Schwarzschild radii). A wide range of black hole masses (MBH) and Eddington ratios (ε) was investigated to study the conditions causing the line-driven winds. For MBH = 106-109 M⊙ and ε = 0.1-0.7, funnel-shaped disk winds appear, in which dense matter is accelerated outward with an opening angle of 70°-80° and with 10% of the speed of light. If we observe the wind along its direction, the velocity, the column density, and the ionization state are consistent with those of the observed UFOs. As long as obscuration by the torus does not affect the observation of X-ray bands, the UFOs could be statistically observed in about 13%-28% of the luminous AGNs, which is not inconsistent with the observed ratio (˜40%). We also found that the results are insensitive to the X-ray luminosity and the density of the disk surface. Thus, we can conclude that UFOs could exist in any luminous AGNs, such as narrow-line Seyfert 1s and quasars with ε > 0.1, with which fast line-driven winds are associated.

  6. Ultra-fast outflows in radio-loud active galactic nuclei

    CERN Document Server

    Tombesi, F; Mushotzky, R F; Ueda, Y; Cappi, M; Gofford, J; Reeves, J N; Guainazzi, M

    2014-01-01

    Recent X-ray observations show absorbing winds with velocities up to mildly-relativistic values of the order of ~0.1c in a limited sample of 6 broad-line radio galaxies. They are observed as blue-shifted Fe XXV-XXVI K-shell absorption lines, similarly to the ultra-fast outflows (UFOs) reported in Seyferts and quasars. In this work we extend the search for such Fe K absorption lines to a larger sample of 26 radio-loud AGNs observed with XMM-Newton and Suzaku. The sample is drawn from the Swift BAT 58-month catalog and blazars are excluded. X-ray bright FR II radio galaxies constitute the majority of the sources. Combining the results of this analysis with those in the literature we find that UFOs are detected in >27% of the sources. However, correcting for the number of spectra with insufficient signal-to-noise, we can estimate that the incidence of UFOs is this sample of radio-loud AGNs is likely in the range f=(50+/-20)%. A photo-ionization modeling of the absorption lines with XSTAR allows to estimate the d...

  7. The Azimuthal Dependence of Outflows and Accretion Detected Using OVI Absorption

    CERN Document Server

    Kacprzak, Glenn G; Churchill, Christopher W; Nielsen, Nikole M; Charlton, Jane C

    2015-01-01

    We report a bimodality in the azimuthal angle ($\\Phi$) distribution of gas around galaxies traced by OVI absorption. We present the mean $\\Phi$ probability distribution function of 29 HST-imaged OVI absorbing (EW>0.1A) and 24~non-absorbing (EW<0.1A) isolated galaxies (0.08quasars. We show that EW is anti-correlated with impact parameter and OVI covering fraction decreases from 80% within 50kpc to 33% at 200kpc. The presence of OVI absorption is azimuthally dependent and occurs between $\\pm10-20^{\\circ}$ of the galaxy projected major axis and within $\\pm30^{\\circ}$ of the projected minor axis. We find higher EWs along the projected minor axis with weaker EWs along the project major axis. Highly inclined galaxies have the lowest covering fractions due to minimized outflow/inflow cross-section geometry. Absorbing galaxies also have bluer colors while non-absorbers have redder colors, suggesting that star-formation is a key driver in the OVI detection rate. OVI surrou...

  8. Misalignment of Magnetic Fields and Outflows in Protostellar Cores

    OpenAIRE

    Hull, Charles L. H.; Plambeck, Richard L.; Bolatto, Alberto D.; Bower, Geoffrey C.; Carpenter, John M.; Crutcher, Richard M.; Fiege, Jason D.; Franzmann, Erica; Hakobian, Nicholas S.; Heiles, Carl; Houde, Martin; Hughes, A. Meredith; Jameson, Katherine; Kwon, Woojin; Lamb, James W.

    2012-01-01

    We present results of λ1.3 mm dust-polarization observations toward 16 nearby, low-mass protostars, mapped with ~2."5 resolution at CARMA. The results show that magnetic fields in protostellar cores on scales of ~1000 AU are not tightly aligned with outflows from the protostars. Rather, the data are consistent with scenarios where outflows and magnetic fields are preferentially misaligned (perpendicular), or where they are randomly aligned. If one assumes that outflows emerge along the rotati...

  9. FAR-INFRARED PROPERTIES OF TYPE 1 QUASARS

    Energy Technology Data Exchange (ETDEWEB)

    Hanish, D. J.; Teplitz, H. I.; Capak, P.; Desai, V.; Armus, L.; Brinkworth, C.; Brooke, T.; Colbert, J.; Fadda, D.; Noriega-Crespo, A.; Paladini, R. [Spitzer Science Center, California Institute of Technology, MC 220-6, 1200 E California Blvd., Pasadena, CA 91125 (United States); Frayer, D. [National Radio Astronomy Observatory, P.O. Box 2, Green Bank, WV 24944 (United States); Huynh, M. [International Centre for Radio Astronomy Research, M468, University of Western Australia, Crawley, WA 6009 (Australia); Lacy, M. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Murphy, E. [The Observatories of the Carnegie Institution for Science, Pasadena, CA 91101 (United States); Scarlata, C. [Minnesota Institute for Astrophysics, School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States); Shenoy, S., E-mail: hanish@ipac.caltech.edu [Space Science Division, NASA Ames Research Center, M/S 245-6, Moffett Field, CA 94035 (United States)

    2013-05-01

    We use the Spitzer Space Telescope Enhanced Imaging Products and the Spitzer Archival Far-InfraRed Extragalactic Survey to study the spectral energy distributions (SEDs) of spectroscopically confirmed type 1 quasars selected from the Sloan Digital Sky Survey (SDSS). By combining the Spitzer and SDSS data with the Two Micron All Sky Survey, we are able to construct a statistically robust rest-frame 0.1-100 {mu}m type 1 quasar template. We find that the quasar population is well-described by a single power-law SED at wavelengths less than 20 {mu}m, in good agreement with previous work. However, at longer wavelengths, we find a significant excess in infrared luminosity above an extrapolated power-law, along with significant object-to-object dispersion in the SED. The mean excess reaches a maximum of 0.8 dex at rest-frame wavelengths near 100 {mu}m.

  10. Far-Infrared Properties of Type 1 Quasars

    CERN Document Server

    Hanish, D J; Capak, P; Desai, V; Armus, L; Brinkworth, C; Brooke, T; Colbert, J; Fadda, D; Frayer, D; Huynh, M; Lacy, M; Murphy, E; Noriega-Crespo, A; Paladini, R; Scarlata, C; Shenoy, S

    2013-01-01

    We use the Spitzer Space Telescope Enhanced Imaging Products (SEIP) and the Spitzer Archival Far-InfraRed Extragalactic Survey (SAFIRES) to study the spectral energy distributions of spectroscopically confirmed type 1 quasars selected from the Sloan Digital Sky Survey (SDSS). By combining the Spitzer and SDSS data with the 2-Micron All Sky Survey (2MASS) we are able to construct a statistically robust rest-frame 0.1-100 micron type 1 quasar template. We find the quasar population is well-described by a single power-law SED at wavelengths less than 20 microns, in good agreement with previous work. However, at longer wavelengths we find a significant excess in infrared luminosity above an extrapolated power-law, along with signifiant object-to-object dispersion in the SED. The mean excess reaches a maximum of 0.8 dex at rest-frame wavelengths near 100 microns.

  11. On the Size of HII Regions around High Redshift Quasars

    CERN Document Server

    Maselli, A; Ferrara, A; Choudhury, T R

    2006-01-01

    We investigate the possibility of constraining the ionization state of the Intergalactic Medium (IGM) close to the end of reionization (z ~ 6) by measuring the size of the HII regions in high-z quasars spectra. We perform a combination of multiphase SPH and 3D radiative transfer (RT) simulations to reliably predict the properties of typical high-z quasar HII regions, embedded in a partly neutral IGM. From the analysis of mock spectra along lines of sight through the simulated QSO environment we find that the HII region size derived from quasar spectra is on average 30 % smaller than the physical one. Additional maximum likelihood analysis shows that this offset induces an overestimate of the neutral hydrogen fraction, x_HI, by a factor ~ 3. By applying the same statistical method to a sample of observed QSOs our study favors a mostly ionized (x_HI < 0.06) universe at z=6.1.

  12. Optical variability of quasars: a damped random walk

    CERN Document Server

    Ivezic, Zeljko

    2013-01-01

    A damped random walk is a stochastic process, defined by an exponential covariance matrix that behaves as a random walk for short time scales and asymptotically achieves a finite variability amplitude at long time scales. Over the last few years, it has been demonstrated, mostly but not exclusively using SDSS data, that a damped random walk model provides a satisfactory statistical description of observed quasar variability in the optical wavelength range, for rest-frame timescales from 5 days to 2000 days. The best-fit characteristic timescale and asymptotic variability amplitude scale with the luminosity, black hole mass, and rest wavelength, and appear independent of redshift. In addition to providing insights into the physics of quasar variability, the best-fit model parameters can be used to efficiently separate quasars from stars in imaging surveys with adequate long-term multi-epoch data, such as expected from LSST.

  13. High-redshift quasar host galaxies with adaptive optics

    CERN Document Server

    Kuhlbrodt, B; Wisotzki, L; Jahnke, K

    2005-01-01

    We present K band adaptive optics observations of three high-redshift (z ~ 2.2) high-luminosity quasars, all of which were studied for the first time. We also bserved several point spread function (PSF) calibrators, non-simultaneously because of the small field of view. The significant temporal PSF variations on timescales of minutes inhibited a straightforward scaled PSF removal from the quasar images. Characterising the degree of PSF concentration by the radii encircling 20% and 80% of the total flux, respectively, we found that even under very different observing conditions the r20 vs. r80 relation varied coherently between individual short exposure images, delineating a well-defined relation for point sources. Placing the quasar images on this relation, we see indications that all three objects were resolved. We designed a procedure to estimate the significance of this result, and to estimate host galaxy parameters, by reproducing the statistical distribution of the individual short exposure images. We fi...

  14. PG 1411 + 442 - The nearest broad absorption line quasar

    Science.gov (United States)

    Malkan, Matthew A.; Green, Richard F.; Hutchings, John B.

    1987-01-01

    IUE observations reveal strong, moderately broad absorption troughs in the blue wings of the C IV and N V emission lines of the quasar PG 1411 + 442. No absorption from weakly ionized gas is detected. The emission-line strengths and overall shape of the ultraviolet/optical/near-infrared/far-infrared continuum of the new broad absorption line quasar are within the range normally measured in quasars. Its redshift is low enough to allow the morphology of the host galaxy to be studied in deep broad-band and intermediate-band CCD images. The galaxy appears to be a large spiral with a very long arm or tail. The inclination angle is 57 deg, which rules out the possibility that the line of sight to the nucleus intersects a large path length in a galactic disk.

  15. Microlensing in the double quasar SBS1520+530

    CERN Document Server

    Gaynullina, E R; Akhunov, T; Burkhonov, O M; Gottlöber, S; Mirtadjieva, K; Nuritdinov, S N; Tadjibaev, I; Wambsganss, J; Wisotzki, L

    2005-01-01

    We present the results of a monitoring campaign of the double quasar SBS1520+530 at Maidanak observatory from April 2003 to August 2004. We obtained light curves in V and R filters that show small-amplitude \\Delta m~0.1 mag intrinsic variations of the quasar on time scales of about 100 days. The data set is consistent with the previously determined time delay of \\Delta t=(130+-3) days by Burud et al. (2002). We find that the time delay corrected magnitude difference between the quasar images is now larger by (0.14+-0.03) mag than during the observations by Burud et al. (2002). This confirms the presence of gravitational microlensing variations in this system.

  16. The circum-galactic medium of quasars: CIV absorption systems

    CERN Document Server

    Landoni, M; Treves, A; Scarpa, R; Farina, E P

    2015-01-01

    We investigate the properties of the circumgalactic gas in the halo of quasar host galaxies from CIV absorption line systems. Optical spectroscopy of closely aligned pairs of quasars (projected distance \\leq 200 kpc) obtained at the Gran Telescopio Canarias is used to investigate the distribution of the absorbing gas for a sample of 18 quasars at z \\sim 2. We found that the detected absorption systems of EW \\geq 0.3Ang associated with the foreground QSO are revealed up to 200 kpc from the center of the host galaxy. The structure of the absorbing gas is rather patchy with a covering fraction of the gas that quickly decreases beyond 100 kpc. These results are in qualitative agreement with those found for the lower ionisation metal Mg II 2800 Ang.

  17. X-ray evidence for ultra-fast outflows in Seyfert galaxies

    Science.gov (United States)

    Tombesi, Francesco; Braito, Valentina; Reeves, James; Cappi, Massimo; Dadina, Mauro

    2012-07-01

    X-ray evidence for massive, highly ionized, ultra-fast outflows (UFOs) has been recently reported in a number of AGNs through the detection of blue-shifted Fe XXV/XXVI absorption lines. We present the results of a comprehensive spectral analysis of a large sample of 42 local Seyferts observed with XMM-Newton. Similar results are also obtained from a Suzaku analysis of 5 radio galaxies. We find that UFOs are common phenomena, being present in >40% of the sources. Their outflow velocity distribution is in the range ˜0.03--0.3c, with mean value of ˜0.14c. The ionization parameter is very high, in the range logξ˜3--6 erg~s^{-1}~cm, and the associated column densities are also large, in the range ˜10^{22}--10^{24} cm^{-2}. Their location is constrained at ˜0.0003--0.03pc (˜10^2--10^4 r_s) from the central black hole, consistent with what is expected for accretion disk winds/outflows. The mass outflow rates are in the interval ˜0.01--1M_{⊙}~yr^{-1}. The associated mechanical power is also high, in the range ˜10^{43}--10^{45} erg/s, which indicates that UFOs are capable to provide a significant contribution to the AGN cosmological feedback.

  18. The Co-Formation of Spheroids and Quasars Traced in their Clustering

    Science.gov (United States)

    Hopkins, Philip F.; Lidz, Adam; Hernquist, Lars; Coil, Alison L.; Myers, Adam D.; Cox, Thomas J.; Spergel, David N.

    2007-06-01

    We compare observed clustering of quasars and galaxies as a function of redshift, mass, luminosity, and color/morphology, to constrain models of quasar fueling and the co-evolution of spheroids and supermassive black holes (BHs). High-redshift quasars are shown to be drawn from the progenitors of local early-type galaxies, with the characteristic quasar luminosity L* reflecting a characteristic mass of ``active'' BH/host populations at each epoch. Evolving observed high-z quasar clustering to z=0 predicts a trend of clustering in ``quasar remnants'' as a function of stellar mass identical to that observed for early types. However, quasar clustering does not simply reflect observed early (or late) type populations; at each redshift, quasars cluster as an ``intermediate'' population. Comparing with the age of elliptical stellar populations as a function of mass reveals that this ``intermediate'' population represents those ellipticals undergoing or terminating their final significant star formation activity at the given epoch. Assuming that quasar triggering is associated with the formation/termination epoch of ellipticals predicts quasar clustering at all observed redshifts without any model dependence or assumptions about quasar light curves, lifetimes, or accretion rates. This is not true for disks or quasar halos; i.e., quasars do not generically trace star formation or halo assembly. Quasar clustering at all redshifts is consistent with ~4×1012 h-1 Msolar, similar to group scales. This supports scenarios in which major mergers dominate the bright, high-redshift quasar populations. We show how improved clustering measurements can be used to constrain lower luminosity AGN fueling and whether or not accretion/star formation can ``shut down'' at z>3.

  19. Locating star-forming regions in quasar host galaxies

    Science.gov (United States)

    Young, J. E.; Eracleous, M.; Shemmer, O.; Netzer, H.; Gronwall, C.; Lutz, Dieter; Ciardullo, R.; Sturm, Eckhard

    2014-02-01

    We present a study of the morphology and intensity of star formation in the host galaxies of eight Palomar-Green quasars using observations with the Hubble Space Telescope. Our observations are motivated by recent evidence for a close relationship between black hole growth and the stellar mass evolution in its host galaxy. We use narrow-band [O II]λ3727, Hβ, [O III]λ5007 and Paα images, taken with the Wide Field Planetary Camera 2 and NICMOS instruments, to map the morphology of line-emitting regions, and, after extinction corrections, diagnose the excitation mechanism and infer star-formation rates. Significant challenges in this type of work are the separation of the quasar light from the stellar continuum and the quasar-excited gas from the star-forming regions. To this end, we present a novel technique for image decomposition and subtraction of quasar light. Our primary result is the detection of extended line-emitting regions with sizes ranging from 0.5 to 5 kpc and distributed symmetrically around the nucleus, powered primarily by star formation. We determine star-formation rates of the order of a few tens of M⊙ yr-1. The host galaxies of our target quasars have stellar masses of the order of 1011 M⊙ and specific star-formation rates on a par with those of M82 and luminous infrared galaxies. As such they fall at the upper envelope or just above the star-formation mass sequence in the specific star formation versus stellar mass diagram. We see a clear trend of increasing star-formation rate with quasar luminosity, reinforcing the link between the growth of the stellar mass of the host and the black hole mass found by other authors.

  20. Environments of strong/ultrastrong, ultraviolet Fe II emitting quasars

    Science.gov (United States)

    Clowes, Roger G.; Raghunathan, Srinivasan; Söchting, Ilona K.; Graham, Matthew J.; Campusano, Luis E.

    2013-08-01

    We have investigated the strength of ultraviolet (UV) Fe II emission from quasars within the environments of large quasar groups (LQGs) in comparison with quasars elsewhere, for 1.1 ≤ zLQG ≤ 1.7, using the DR7QSO catalogue of the Sloan Digital Sky Survey. We use the Weymann et al. W2400 equivalent width, defined between the rest-frame continuum windows 2240-2255 and 2665-2695 Å, as the measure of the UV Fe II emission. We find a significant shift of the W2400 distribution to higher values for quasars within LQGs, predominantly for those LQGs with 1.1 ≤ zLQG ≤ 1.5. There is a tentative indication that the shift to higher values increases with the quasar i magnitude. We find evidence that within LQGs the ultrastrong emitters with W2400 ≥ 45 Å (more precisely, ultrastrong plus with W2400 ≥ 44 Å) have preferred nearest-neighbour separations of ˜30-50 Mpc to the adjacent quasar of any W2400 strength. No such effect is seen for the ultrastrong emitters that are not in LQGs. The possibilities for increasing the strength of the Fe II emission appear to be iron abundance, Lyα fluorescence and microturbulence, and probably all of these operate. The dense environment of the LQGs may have led to an increased rate of star formation and an enhanced abundance of iron in the nuclei of galaxies. Similarly, the dense environment may have led to more active blackholes and increased Lyα fluorescence. The preferred nearest-neighbour separation for the stronger emitters would appear to suggest a dynamical component, such as microturbulence. In one particular LQG, the Huge-LQG (the largest structure known in the early Universe), six of the seven strongest emitters very obviously form three pairings within the total of 73 members.

  1. Black holes, quasars, and the universe /2nd edition/

    Science.gov (United States)

    Shipman, H. L.

    1980-01-01

    Topics of astronomy are discussed in terms of black holes, galaxies, quasars, and models of the universe. Black holes are approached through consideration of stellar evolution, white dwarfs, supernovae, neutron stars, pulsars, the event horizon, Cygnus X-1, white holes, and worm holes. Attention is also given to radio waves from high speed electrons, the radiation emitted by quasars, active galaxies, galactic energy sources, and interpretations of the redshift. Finally, the life cycle of the universe is deliberated, along with the cosmic time scale, evidence for the Big Bang, and the future of the universe.

  2. Using Quasars as Standard Candles for Studying Dark Energy

    DEFF Research Database (Denmark)

    Denney, Kelly D.; Vestergaard, Marianne; Watson, D.

    2012-01-01

    We have recently demonstrated (Watson et al. 2011, ApJ, 740, L49) that quasars, or more generally active galactic nuclei (AGNs), can be used as standard candles for measuring distances in the universe, similar to Type Ia supernovae (SNe). Here, we present the initial findings of this new method......, which relies on the technique of reverberation mapping to measure time delays between the quasar continuum and emission line variability signatures. Measuring this time delay effectively measures the radius between the central source and the emission-line gas. The emission line gas is photo...

  3. High-Redshift Quasars at the Highest Resolution: VSOP Results

    Science.gov (United States)

    Frey, S.; Gurvits, L. I.; Lobanov, A. P.; Schilizzi, R. T.; Paragi, Z.

    2009-08-01

    We studied the radio structure of high-redshift (z>3) quasars with VSOP at 1.6 and 5 GHz. These sources are the most distant objects ever observed with Space VLBI, at rest-frame frequencies up to ˜25 GHz. Here we give an account of the observations and briefly highlight the most interesting cases and results. These observations allowed us, among other things, to estimate the mass of the central black holes powering these quasars, to identify large misalignments between the milli-arcsecond (mas) and sub-mas scale radio structures, and to detect apparent superluminal motion at sub-mas scale.

  4. Quasar Formation and Energy Emission in Black Hole Universe

    Directory of Open Access Journals (Sweden)

    Zhang T. X.

    2012-07-01

    Full Text Available Formation and energy emission of quasars are investigated in accord with the black hole universe, a new cosmological model recently developed by Zhang. According to this new cosmological model, the universe originated from a star-like black hole and grew through a supermassive black hole to the present universe by accreting ambient matter and merging with other black holes. The origin, structure, evolution, expansion, and cosmic microwave background radiation of the black hole universe have been fully ex- plained in Paper I and II. This study as Paper III explains how a quasar forms, ignites and releases energy as an amount of that emitted by dozens of galaxies. A main sequence star, after its fuel supply runs out, will, in terms of its mass, form a dwarf, a neutron star, or a black hole. A normal galaxy, after its most stars have run out of their fuels and formed dwarfs, neutron stars, and black holes, will eventually shrink its size and collapse towards the center by gravity to form a supermassive black hole with billions of solar masses. This collapse leads to that extremely hot stellar black holes merge each other and further into the massive black hole at the center and meantime release a huge amount of radiation energy that can be as great as that of a quasar. Therefore, when the stellar black holes of a galaxy collapse and merge into a supermassive black hole, the galaxy is activated and a quasar is born. In the black hole universe, the observed dis- tant quasars powered by supermassive black holes can be understood as donuts from the mother universe. They were actually formed in the mother universe and then swallowed into our universe. The nearby galaxies are still very young and thus quiet at the present time. They will be activated and further evolve into quasars after billions of years. At that time, they will enter the universe formed by the currently observed distant quasars as similar to the distant quasars entered our universe

  5. Shocks in nova outflows. I. Thermal emission

    CERN Document Server

    Metzger, Brian D; Vurm, Indrek; Beloborodov, Andrei M; Chomiuk, Laura; Sokoloski, J L; Nelson, Thomas

    2014-01-01

    Evidence for shocks in nova outflows include (1) multiple velocity components in the optical spectra; (2) keV X-ray emission weeks to months after the outburst; (3) early radio flare on timescales of months, in excess of that predicted from the freely expanding photo-ionized gas; and (4) ~ GeV gamma-rays. We present a 1D model for the shock interaction between the fast nova outflow and a dense external shell (DES) and its associated thermal X-ray, optical, and radio emission. The forward shock is radiative initially when the density of shocked gas is highest, at which times radio emission originates from the dense cooling layer immediately downstream of the shock. The radio light curve is characterized by sharper rises to maximum and later peak times at progressively lower frequencies, with a peak brightness temperature that is approximately independent of frequency. We apply our model to the recent gamma-ray classical nova V1324 Sco, obtaining an adequate fit to the early radio maximum for reasonable assumpt...

  6. Jet driven molecular outflows in Orion

    CERN Document Server

    Rodríguez-Franco, A; Wilson, T L

    1999-01-01

    We present high sensitivity and high angular resolution images of the high velocity (vLSR>30kms^-1) CO emission in the J=1-0 and J=2-1 lines of the Orion KL region. These results reveal the morphology of the high-velocity CO emission at the most extreme velocities. High velocity emission have been only detected in two regions: BN/KL (IRc2/I) and Orion-S. The Orion-S region contains a very young (dynamical age of 10^3years), very fast (~110kms^-1) and very compact (<0.16pc) bipolar outflow. From the morphology of the high-velocity gas we estimate that the position of the powering source must be ~20'' north of FIR4. For the IRc2/I molecular outflow the morphology of the moderate velocity (<60kms^-1) gas shows a weak bipolarity around IRc2/I. The gas at the most extreme velocities does not show any bipolarity around IRc2/I, if any, it is found ~30'' north from these sources. The blue and redshifted gas at moderate velocities shows similar spatial distribution with a systematic trend for the size of the hig...

  7. Ionized Outflows from Compact Steep Spectrum Sources

    CERN Document Server

    Shih, Hsin-Yi; Kewley, Lisa

    2013-01-01

    Massive outflows are known to exist, in the form of extended emission-line regions (EELRs), around about one-third of powerful FR II radio sources. We investigate the origin of these EELRs by studying the emission-line regions around compact-steep-spectrum (CSS) radio galaxies that are younger (10$^3$ to 10$^5$ years old) versions of the FR II radio galaxies. We have searched for and analyzed the emission-line regions around 11 CSS sources by taking integral field spectra using GMOS on Gemini North. We fit the [\\ion{O}{3}] $\\lambda 5007$ line and present the velocity maps for each detected emission-line region. We find, in most cases, that the emission-line regions have multi-component velocity structures with different velocity dispersions and/or flux distributions for each component. The velocity gradients of the emission-line gas are mostly well aligned with the radio axis, suggesting a direct causal link between the outflowing gas and the radio jets. The complex velocity structure may be a result of diffe...

  8. Multidimensional chemical modelling, II. Irradiated outflow walls

    CERN Document Server

    Bruderer, Simon; Doty, Steven D; van Dishoeck, Ewine F; Bourke, Tyler L

    2009-01-01

    Observations of the high-mass star forming region AFGL 2591 reveal a large abundance of CO+, a molecule known to be enhanced by far UV (FUV) and X-ray irradiation. In chemical models assuming a spherically symmetric envelope, the volume of gas irradiated by protostellar FUV radiation is very small due to the high extinction by dust. The abundance of CO+ is thus underpredicted by orders of magnitude. In a more realistic model, FUV photons can escape through an outflow region and irradiate gas at the border to the envelope. Thus, we introduce the first 2D axi-symmetric chemical model of the envelope of a high-mass star forming region to explain the CO+ observations as a prototypical FUV tracer. The model assumes an axi-symmetric power-law density structure with a cavity due to the outflow. The local FUV flux is calculated by a Monte Carlo radiative transfer code taking scattering on dust into account. A grid of precalculated chemical abundances, introduced in the first part of this series of papers, is used to ...

  9. Discovery of 16 New z ∼ 5.5 Quasars: Filling in the Redshift Gap of Quasar Color Selection

    Science.gov (United States)

    Yang, Jinyi; Fan, Xiaohui; Wu, Xue-Bing; Wang, Feige; Bian, Fuyan; Yang, Qian; McGreer, Ian D.; Yi, Weimin; Jiang, Linhua; Green, Richard; Yue, Minghao; Wang, Shu; Li, Zefeng; Ding, Jiani; Dye, Simon; Lawrence, Andy

    2017-04-01

    We present initial results from the first systematic survey of luminous z ∼ 5.5 quasars. Quasars at z ∼ 5.5, the post-reionization epoch, are crucial tools to explore the evolution of intergalactic medium, quasar evolution, and the early super-massive black hole growth. However, it has been very challenging to select quasars at redshifts 5.3 ≤ z ≤ 5.7 using conventional color selections, due to their similar optical colors to late-type stars, especially M dwarfs, resulting in a glaring redshift gap in quasar redshift distributions. We develop a new selection technique for z ∼ 5.5 quasars based on optical, near-IR, and mid-IR photometric data from Sloan Digital Sky Survey (SDSS), UKIRT InfraRed Deep Sky Surveys—Large Area Survey (ULAS), VISTA Hemisphere Survey (VHS), and Wide Field Infrared Survey Explorer. From our pilot observations in the SDSS-ULAS/VHS area, we have discovered 15 new quasars at 5.3 ≤ z ≤ 5.7 and 6 new lower redshift quasars, with SDSS z band magnitude brighter than 20.5. Including other two z ∼ 5.5 quasars already published in our previous work, we now construct a uniform quasar sample at 5.3 ≤ z ≤ 5.7, with 17 quasars in a ∼4800 square degree survey area. For further application in a larger survey area, we apply our selection pipeline to do a test selection by using the new wide field J-band photometric data from a preliminary version of the UKIRT Hemisphere Survey (UHS). We successfully discover the first UHS selected z ∼ 5.5 quasar.

  10. Measurement of Outflow Facility Using iPerfusion.

    Directory of Open Access Journals (Sweden)

    Joseph M Sherwood

    Full Text Available Elevated intraocular pressure (IOP is the predominant risk factor for glaucoma, and reducing IOP is the only successful strategy to prevent further glaucomatous vision loss. IOP is determined by the balance between the rates of aqueous humour secretion and outflow, and a pathological reduction in the hydraulic conductance of outflow, known as outflow facility, is responsible for IOP elevation in glaucoma. Mouse models are often used to investigate the mechanisms controlling outflow facility, but the diminutive size of the mouse eye makes measurement of outflow technically challenging. In this study, we present a new approach to measure and analyse outflow facility using iPerfusion™, which incorporates an actuated pressure reservoir, thermal flow sensor, differential pressure measurement and an automated computerised interface. In enucleated eyes from C57BL/6J mice, the flow-pressure relationship is highly non-linear and is well represented by an empirical power law model that describes the pressure dependence of outflow facility. At zero pressure, the measured flow is indistinguishable from zero, confirming the absence of any significant pressure independent flow in enucleated eyes. Comparison with the commonly used 2-parameter linear outflow model reveals that inappropriate application of a linear fit to a non-linear flow-pressure relationship introduces considerable errors in the estimation of outflow facility and leads to the false impression of pressure-independent outflow. Data from a population of enucleated eyes from C57BL/6J mice show that outflow facility is best described by a lognormal distribution, with 6-fold variability between individuals, but with relatively tight correlation of facility between fellow eyes. iPerfusion represents a platform technology to accurately and robustly characterise the flow-pressure relationship in enucleated mouse eyes for the purpose of glaucoma research and with minor modifications, may be applied

  11. The Multi-Wavelength Quasar Survey Ⅳ. Quasars in the Leo Cluster

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    We aim to provide a quasar sample that is more complete than any previous surveys by using a combined selection technique to reduce the selection effects. Here we present the observational results for the X-ray candidates in the field of the Leo Cluster. We found 33 X-ray AGNs in this field of which 10 are new discoveries. The X-ray data and optical spectra of these AGNs are given. We also study the near-IR properties of the X-ray-selected AGNs by using the data from 2MASS. Most of the AGNs in our sample span the color range 0.0 < B- J < 2.5, 1.0 < J-Ks < 2.0 and 0.5 < H-Ks < 1.2.

  12. The Host Galaxies of X-ray Quasars Are Not Strong Star Formers

    CERN Document Server

    Barger, A J; Owen, F N; Chen, C -C; Hasinger, G; Hsu, L -Y; Li, Y

    2014-01-01

    We use ultradeep SCUBA-2 850um observations (~0.37 mJy rms) of the 2 Ms CDF-N and 4 Ms CDF-S X-ray fields to examine the amount of dusty star formation taking place in the host galaxies of high-redshift X-ray AGNs. Supplementing with COSMOS, we measure the submillimeter fluxes of the 4-8 keV sources at z>1, finding little flux at the highest X-ray luminosities but significant flux at intermediate luminosities. We determine grey body and MIR luminosities by fitting spectral energy distributions to each X-ray source and to each radio source in an ultradeep Karl G. Jansky VLA 1.4 GHz (11.5uJy at 5-sigma) image of the CDF-N. We confirm the FIR-radio and MIR-radio correlations to z=4 using the non-X-ray detected radio sources. Both correlations are also obeyed by the X-ray less luminous AGNs but not by the X-ray quasars. We interpret the low FIR luminosities relative to the MIR for the X-ray quasars as being due to a lack of star formation, while the MIR stays high due to the AGN contribution. We find that the FIR...

  13. A new analysis of fine-structure constant measurements and modelling errors from quasar absorption lines

    CERN Document Server

    Wilczynska, Michael R; King, Julian A; Murphy, Michael T; Bainbridge, Matthew B; Flambaum, Victor V

    2015-01-01

    We present an analysis of 23 absorption systems along the lines of sight towards 18 quasars in the redshift range of $0.4 \\leq z_{abs} \\leq 2.3$ observed on the Very Large Telescope (VLT) using the Ultraviolet and Visual Echelle Spectrograph (UVES). Considering both statistical and systematic error contributions we find a robust estimate of the weighted mean deviation of the fine-structure constant from its current, laboratory value of $\\Delta\\alpha/\\alpha=\\left(0.22\\pm0.23\\right)\\times10^{-5}$, consistent with the dipole variation reported in Webb et al. and King et al. This paper also examines modelling methodologies and systematic effects. In particular we focus on the consequences of fitting quasar absorption systems with too few absorbing components and of selectively fitting only the stronger components in an absorption complex. We show that using insufficient continuum regions around an absorption complex causes a significant increase in the scatter of a sample of $\\Delta\\alpha/\\alpha$ measurements, th...

  14. Simple Stellar Population Modeling of Low S/N Galaxy Spectra and Quasar Host Galaxy Applications

    CERN Document Server

    Mosby, Gregory; Hooper, Eric; Wolf, Marsha; Sheinis, Andrew; Richards, Joseph

    2014-01-01

    To study the effect of supermassive black holes (SMBHs) on their host galaxies it is important to study the hosts when the SMBH is near its peak activity. A method to investigate the host galaxies of high luminosity quasars is to obtain optical spectra at positions offset from the nucleus where the relative contribution of the quasar and host are comparable. However, at these extended radii the galaxy surface brightness is often low (20-22 mag per arcsec$^{2}$) and the resulting spectrum might have such low S/N that it hinders analysis with standard stellar population modeling techniques. To address this problem we have developed a method that can recover galaxy star formation histories (SFHs) from rest frame optical spectra with S/N $\\sim$ 5~\\AA$^{-1}$. This method uses the statistical technique diffusion k-means to tailor the stellar population modeling basis set. Our diffusion k-means minimal basis set, composed of 4 broad age bins, is successful in recovering a range of galaxy SFHs. Additionally, using an...

  15. Measuring the seeds of thermal ion outflow

    Science.gov (United States)

    Fernandes, Philip A.

    The ionosphere is the primary source for heavy ions which are ubiquitous in the terrestrial magnetosphere. Low-altitude energization in the auroral ionosphere results in bulk heating and transverse acceleration of ions, which begin to upwell and/or be accelerated upward by the mirror force, starting upflow and leading to the outflow process. The details of the processes that seed ion outflow at low altitudes are difficult to measure in situ and thus remain an open question. We examine the observational parameter regime in which ion upflow/outflow initiates. Emphasis is placed on making measurements of the thermal ion kinetic distribution function, allowing for accounting of processes which affect in situ plasma measurements. We consider an electrostatic analyzer (ESA) instrument capable of making the measurements necessary to quantify the roles of various heating mechanisms in initiating ion upflow in the low-altitude auroral ionosphere. We present the difficulties associated with making these measurements and identify instrument design choices that mitigate some of these measurement challenges. Analysis of ESA measurements of the thermal ion distribution function taken on the MICA auroral sounding rocket is presented. Using a Maxwellian model to replicate possible measured spectra, we calculate integrated parameters from the model and compare with equivalent parameters calculated from the in situ data. Through Liouville's theorem and the thin-sheath approximation we couple the measured and forward-modeled parameters such that measurements inside the sheath provide information about the state of the plasma outside the sheath. Throughout the MICA flight, ion upflow is observed and attributed to ambipolar electric fields and/or ion-neutral interactions. Late in the flight we observe quasi-static frictional process driving the ion temperature. Early in the flight we observe ion heating weakly correlated with ELF wave activity; our analysis suggests we must consider

  16. Collective outflow from a small multiple stellar system

    Energy Technology Data Exchange (ETDEWEB)

    Peters, Thomas [Institut für Theoretische Physik, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich (Switzerland); Klaassen, Pamela D. [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Mac Low, Mordecai-Mark [Department of Astrophysics, American Museum of Natural History, 79th Street at Central Park West, New York, NY 10024-5192 (United States); Schrön, Martin; Klessen, Ralf S. [Zentrum für Astronomie der Universität Heidelberg, Institut für Theoretische Astrophysik, Albert-Ueberle-Strasse 2, D-69120 Heidelberg (Germany); Federrath, Christoph [Monash Centre for Astrophysics, School of Mathematical Sciences, Monash University, Vic 3800 (Australia); Smith, Michael D., E-mail: tpeters@physik.uzh.ch [Centre for Astrophysics and Space Science, University of Kent, Canterbury, CT2 7NH (United Kingdom)

    2014-06-10

    The formation of high-mass stars is usually accompanied by powerful protostellar outflows. Such high-mass outflows are not simply scaled-up versions of their lower-mass counterparts, since observations suggest that the collimation degree degrades with stellar mass. Theoretically, the origins of massive outflows remain open to question because radiative feedback and fragmentation of the accretion flow around the most massive stars, with M > 15 M {sub ☉}, may impede the driving of magnetic disk winds. We here present a three-dimensional simulation of the early stages of core fragmentation and massive star formation that includes a subgrid-scale model for protostellar outflows. We find that stars that form in a common accretion flow tend to have aligned outflow axes, so that the individual jets of multiple stars can combine to form a collective outflow. We compare our simulation to observations with synthetic H{sub 2} and CO observations and find that the morphology and kinematics of such a collective outflow resembles some observed massive outflows, such as Cepheus A and DR 21. We finally compare physical quantities derived from simulated observations of our models to the actual values in the models to examine the reliability of standard methods for deriving physical quantities, demonstrating that those methods indeed recover the actual values to within a factor of two to three.

  17. Standing Shocks around Black Holes and Estimation of Outflow Rates

    Indian Academy of Sciences (India)

    Santabrata Das; Sandip K. Chakrabarti

    2002-03-01

    We self-consistently obtain shock locations in an accretion flow by using an analytical method. One can obtain the spectral properties, quasi-periodic oscillation frequencies and the outflowrates when the inflow parameters are known. Since temperature of the CENBOL decides the spectral states of the black hole, and also the outflow rate, the outflow rate is directly related to the spectral states.

  18. Scaling Relations Between Warm Galactic Outflows and Their Host Galaxies

    CERN Document Server

    Chisholm, John; Leitherer, Claus; Chen, Yanmei; Wofford, Aida; Lundgren, Britt

    2014-01-01

    We report on a sample of 51 nearby, star-forming galaxies observed with the Cosmic Origin Spectrograph on the Hubble Space Telescope. We calculate Si II kinematics and densities arising from warm gas entrained in galactic outflows. We use multi-wavelength ancillary data to estimate stellar masses (M$_\\ast$), star-formation rates (SFR), and morphologies. We derive significant correlations between outflow velocity and SFR$^{\\sim 0.1}$, M$_\\ast^{\\sim 0.1}$ and v$_\\text{circ}^{\\sim 1/2}$. Some mergers drive outflows faster than these relations prescribe, launching the outflow faster than the escape velocity. Calculations of the mass outflow rate reveal strong scaling with SFR$^{\\sim 1/2}$ and M$_\\ast^{\\sim 1/2}$. Additionally, mass-loading efficiency factors (mass outflow rate divided by SFR) scale approximately as M$_\\ast^{-1/2}$. Both the outflow velocity and mass-loading scaling suggest that these outflows are powered by supernovae, with only 0.7% of the total supernovae energy converted into the kinetic energ...

  19. Using Quasars as Standard Candles for Studying Dark Energy

    DEFF Research Database (Denmark)

    Denney, Kelly D.; Vestergaard, Marianne; Watson, D.

    2012-01-01

    We have recently demonstrated (Watson et al. 2011, ApJ, 740, L49) that quasars, or more generally active galactic nuclei (AGNs), can be used as standard candles for measuring distances in the universe, similar to Type Ia supernovae (SNe). Here, we present the initial findings of this new method...

  20. Multifrequency observations of the flaring quasar 1156+295

    Science.gov (United States)

    Glassgold, A. E.; Bregman, J. N.; Huggins, P. J.; Kinney, A. L.; Pica, A. J.; Pollock, J. T.; Leacock, R. J.; Smith, A. G.; Webb, J. R.; Wisniewski, W. Z.

    1983-01-01

    A report is presented on the optically violent variable quasar 1156+295, known also as 4C 29.45 and Ton 599. A large outburst of this quasar was discovered in April 1981 in the course of a program to obtain simultaneous multifrequency spectra of variable quasars. Ultraviolet observations taken with the International Ultraviolet Explorer satellite were coordinated with ground-based observations at radio, infrared, and optical wavelengths. Measurements were made at four epochs starting immediately after the outburst was discovered, when the B-magnitude was 14.0, and at intervals of 4 days, 60 days and 1 year. The luminosity integrated only over observed wavelength bands was approximately 3 x 10 to the 48th ergs/sec on the first epoch of observation. Modeling of the source with a synchrotron self-Compton model suggests that the core of the source has a linear dimension of 0.01 pc, a magnetic field strength in the range 0.1-30 gauss, and a bulk relativistic motion in the quasar rest frame characterized by a Lorentz factor in the range 2-8.