5,657 research outputs found

    Quasar outflow energetics from broad absorption line variability

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    Quasar outflows have long been recognized as potential contributors to the co-evolution between supermassive black holes (SMBHs) and their host galaxies. The role of outflows in AGN feedback processes can be better understood by placing observational constraints on wind locations and kinetic energies. We utilize broad absorption line (BAL) variability to investigate the properties of a sample of 71 BAL quasars with P\thinspaceV broad absorption. The presence of P\thinspaceV BALs indicates that other BALs like C\thinspaceIV are saturated, such that variability in those lines favours clouds crossing the line of sight. We use these constraints with measurements of BAL variability to estimate outflow locations and energetics. Our data set consists of multiple-epoch spectra from the Sloan Digital Sky Survey and MDM Observatory. We detect significant (4σ\sigma) BAL variations from 10 quasars in our sample over rest frame time-scales between < 0.2-3.8 yr. Our derived distances for the 10 variable outflows are nominally < 1-10 pc from the SMBH using the transverse-motion scenario, and < 100-1000 pc from the central source using ionization-change considerations. These distances, in combination with the estimated high outflow column densities (i.e. NHN_{\textrm{H}} > 1022^{22} cm2^{-2}), yield outflow kinetic luminosities between ~ 0.001-1 times the bolometric luminosity of the quasar, indicating that many absorber energies within our sample are viable for AGN feedback.Comment: 19 pages, 3 figures, 4 tables, 1 supplementary figure, accepted to MNRA

    Some characteristics of adaptation in am1

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    Adaptation in am

    Identification of individual enzymes in crude extracts by acrylamide gel electrophoresis

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    Identification of enzymes by acrylamide gel electrophoresi

    Constraining FeLoBAL outflows from absorption line variability

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    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 the supermassive black hole (SMBH) to be less than 69, 7, and 60 pc for our three variable sources. In combination with other studies, these results suggest that the outflowing gas in FeLoBAL quasars resides on a range of scales and includes matter within tens of parsecs of the central source.Comment: 21 pages, 6 figures, 2 supplementary figures (attached at the end of the manuscript), accepted to Monthly Notices of the Royal Astronomical Societ

    Trust, Reciprocity and Rules

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    In the absence of enforceable contracts, many economic and personal interactions rely on trust and reciprocity. Research shows that although this reliance often works well, sometimes it breaks down. Simple rules mandating minimum standards on reciprocation prevent the most egregious trust violations, but may also undermine behavior that would have otherwise produced higher overall economic welfare. We test the efficacy of exogenously imposed minimum return rules using experimental trust games. We find that rules fail to increase trust and trustworthiness. Thus low minimum standards significantly decrease economic welfare. Although sufficiently restrictive rules restore welfare, trust and trustworthy behavior never returns.trust games, experiments, reputation, information, reciprocity

    Nesting Success in Ohio's Endangered Common Tern

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    Author Institution: School of Natural Resources, The Ohio State University ; Ohio Agricultural Research and Development CenterNesting success of Ohio's endangered common tern (Sterna hirundo) population was studied during 1980 at Lucas County Port Authority Facility No. 3 (F3) located near Toledo in Maumee Bay, Lake Erie. Ninety-one clutches in three of eight tern subcolonies at this site were studied in detail. Sixty-nine percent (157/229) of the eggs failed to hatch, and abandonment of nests during incubation was responsible for nearly half of the hatching failures. Most abandonments were believed caused by nocturnal visits to nest sites by a feral cat. Observations at the fourth subcolony indicated that vegetation overgrowing nests and encroachment by juvenile ring-billed gulls (Larus delawarensis) caused additional nest abandonments. Fledging success in the three subcolonies studied in detail was estimated at 0.62 chicks fledged/nest. Production in 1980 was below replacement. Continued reproductive failures will result in extirpation of the common tern from Ohio

    Problems involved in establishing a new foundry in the New England area

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    Thesis (B.S.) Massachusetts Institute of Technology. Dept. of Business and Engineering Administration, 1952.MIT copy bound with: Development of a cost control system for a textile specialty plant / William Edwin Moss. 1952.Bibliography: leaves 106-107.by George M. Shields, Jr., Edward W. Neumann, Jr.B.S

    Recoiling Black Holes in Quasars

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    Recent simulations of merging black holes with spin give recoil velocities from gravitational radiation up to several thousand km/s. A recoiling supermassive black hole can retain the inner part of its accretion disk, providing fuel for a continuing QSO phase lasting millions of years as the hole moves away from the galactic nucleus. One possible observational manifestation of a recoiling accretion disk is in QSO emission lines shifted in velocity from the host galaxy. We have examined QSOs from the Sloan Digital Sky Survey with broad emission lines substantially shifted relative to the narrow lines. We find no convincing evidence for recoiling black holes carrying accretion disks. We place an upper limit on the incidence of recoiling black holes in QSOs of 4% for kicks greater than 500 km/s and 0.35% for kicks greater than 1000 km/s line-of-sight velocity.Comment: 4 pages, 4 figures, uses emulateapj, Submitted to ApJ Letter
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