2,298 research outputs found
Optical and X-ray Properties of the Swift BAT-detected AGN
The Swift Gamma-Ray Burst satellite has detected a largely unbiased towards
absorption sample of local () 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 H 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
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
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
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
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
- âŠ