2,296 research outputs found

    Optical and X-ray Properties of the Swift BAT-detected AGN

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    The Swift Gamma-Ray Burst satellite has detected a largely unbiased towards absorption sample of local (≈0.03 \approx 0.03) AGN, based solely on their 14--195 keV flux. In the first 9 months of the survey, 153 AGN sources were detected. The X-ray properties in the 0.3--10 keV band have been compiled and presented based on analyses with XMM-Newton, Chandra, Suzaku, and the Swift XRT (Winter et al. 2009). Additionally, we have compiled a sub-sample of sources with medium resolution optical ground-based spectra from the SDSS or our own observations at KPNO. In this sample of 60 sources, we have classified the sources using standard emission line diagnostic plots, obtained masses for the broad line sources through measurement of the broad HÎČ\beta emission line, and measured the [OIII] 5007\AA luminosity of this sample. Based on continuum fits to the intrinsic absorption features, we have obtained clues about the stellar populations of the host galaxies. We now present the highlights of our X-ray and optical studies of this unique sample of local AGNs, including a comparison of the 2--10 keV and 14--195 keV X-ray luminosities with the [OIII] 5007\AA luminosity and the implications of our results towards measurements of bolometric luminosities.Comment: 4 pages, 2 figures, to appear in proceedings for 'X-ray Astronomy 2009', Bologna 09/2009, AIP Conference Series, Eds. A. Comastri, M. Cappi, L. Angelin

    A prescriptive approach to qualify and quantify customer value for value-based requirements engineering

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    Recently, customer-based product development is becoming a popular paradigm. Customer expectations and needs can be identified and transformed into requirements for product design with the help of various methods and tools. However, in many cases, these models fail to focus on the perceived value that is crucial when customers make the decision of purchasing a product. In this paper, a prescriptive approach to support value-based requirements engineering (RE) is proposed, describing the foundations, procedures and initial applications in the context of RE for commercial aircraft. An integrated set of techniques, such as means-ends analysis, part-whole analysis and multi-attribute utility theory is introduced in order to understand customer values in depth and width. Technically, this enables identifying the implicit value, structuring logically collected statements of customer expectations and performing value modelling and simulation. Additionally, it helps to put in place a system to measure customer satisfaction that is derived from the proposed approach. The approach offers significant potential to develop effective value creation strategies for the development of new product

    Unravelling the Mysteries of the Leo Ring: An Absorption Line Study of an Unusual Gas Cloud

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    Since the 1980's discovery of the large (2x10^9 Msun) intergalactic cloud known as the Leo Ring, this object has been the center of a lively debate about its origin. Determining the origin of this object is still important as we develop a deeper understanding of the accretion and feedback processes that shape galaxy evolution. We present HST/COS observations of three sightlines near the Ring, two of which penetrate the high column density neutral hydrogen gas visible in 21 cm observations of the object. These observations provide the first direct measurement of the metallicity of the gas in the Ring, an important clue to its origins. Our best estimate of the metallicity of the ring is ~10% Zsun, higher than expected for primordial gas but lower than expected from an interaction. We discuss possible modifications to the interaction and primordial gas scenarios that would be consistent with this metallicity measurement.Comment: 11 pages, 7 figures, accepted Ap

    Note and Comment

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    Suits Against Trustee; Bills and Notes--Nonnegotiable Notes--Liability of Indorser; Bonds--Joint Stock Association--Negotiability; Carriers--Free Transportation as a Penalty; Carriers--Waiver of Stipulations as to Suits; Constitutional Law--Due Process of Law--Indeterminate Sentence Law; Constitutional Law--Corporations--Foreign Corporations--Exclusion For Removal of Cause to Federal Courts; Constitutional Law--Powers of Constitutional Convention; Criminal Law--Capital Offense--Bail--When Granted; Criminal Law--Murder--Elements of Murder; Damages--Action by Husband for Loss of Wife\u27s Services; Damages--Failure to Deliver Telegram--Mental Suffering--Near Relative; Deeds--Joinder of Infant Husband; Divorce--Temporary Alimony and Counsel Fees--Appeal--Decisions Reviewable; Equity--Sworn Answers as Evidence--Proof to Overcome; Evidence--Opinion Evidence in Action for Libel; Evidence--The Best Evidence Rule; Fraudulent Conveyances--Delivery and Change of Possession of Growing Crops; Garnishment--Exemption--Proceeds of Insurance; Infants--Disaffirming Deed--Ejectment; Judgment--Enjoining Execution on Dormant Judgment; Master and Servant--Liability of Master to Servant for Injury Due to Defective Machinery-

    The Properties of Two Low Redshift O VI Absorbers and Their Associated Galaxies Toward 3C 263

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    Ultraviolet observations of the QSO 3C 263 (zem = 0.652) with COS and FUSE reveal O VI absorption systems at z = 0.06342 and 0.14072 . WIYN multi-object spectrograph observations provide information about the galaxies associated with the absorbers. The multi-phase system at z = 0.06342 traces cool photoionized gas and warm collisionally ionized gas associated with a L ~ 0.31L* compact spiral emission line galaxy with an impact parameter of 63 kpc. The cool photoionized gas in the absorber is well modeled with log U ~ -2.6, log N(H) ~17.8, log n(H) ~ -3.3 and [Si/H] = -0.14\pm0.23. The collisionally ionized gas containing C IV and O VI probably arises in cooling shock heated transition temperature gas with log T ~ 5.5. The absorber is likely tracing circumgalactic gas enriched by gas ejected from the spiral emission line galaxy. The simple system at z = 0.14072 only contains O VI and broad and narrow H I. The O VI with b = 33.4\pm11.9 km s-1 is likely associated with the broad H I {\lambda}1215 absorption with b = 86.7\pm15.4 km s-1. The difference in Doppler parameters implies the detection of a very large column of warm gas with log T = 5.61(+0.16, -0.25), log N(H) = 19.54(+0.26, -0.44) and [O/H] = -1.48 (+0.46, -0.26). This absorber is possibly associated with a 1.6L* absorption line galaxy with an impact parameter of 617 kpc although an origin in warm filament gas or in the halo of a fainter galaxy is more likely.Comment: Accepted by the Astrophysical Journal. 24 pages and 9 figure
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