1,831 research outputs found
X-ray Signatures of Circumnuclear Gas in AGN
X-ray spectra of AGN are complex. X-ray absorption and emission features
trace gas covering a wide range of column densities and ionization states. High
resolution spectra show the absorbing gas to be outflowing, perhaps in the form
of an accretion disk wind. The absorbing complex shapes the form of the X-ray
spectrum while X-ray reverberation and absorption changes explain the spectral
and timing behaviour of AGN. We discuss recent progress, highlighting some new
results and reviewing the implications that can be drawn from the data.Comment: Proceedings of the conference "Suzaku 2011, Exploring the X-ray
Universe: Suzaku and Beyond
The Global Implications of the Hard X-ray Excess in Type 1 AGN
Recent evidence for a strong 'hard excess' of flux at energies > 20 keV in
some Suzaku observations of type 1 Active Galactic Nuclei (AGN) has motivated
an exploratory study of the phenomenon in the local type 1 AGN population. We
have selected all type 1 AGN in the Swift Burst Alert Telescope (BAT) 58-month
catalog and cross-correlated them with the holdings of the Suzaku public
archive. We find the hard excess phenomenon to be a ubiquitous property of type
1 AGN. Taken together, the spectral hardness and equivalent width of Fe K alpha
emission are consistent with reprocessing by an ensemble of Compton-thick
clouds that partially cover the continuum source. In the context of such a
model, ~ 80 % of the sample has a hardness ratio consistent with > 50% covering
of the continuum by low-ionization, Compton-thick gas. More detailed study of
the three hardest X-ray spectra in our sample reveal a sharp Fe K absorption
edge at ~ 7 keV in each of them, indicating that blurred reflection is not
responsible for the very hard spectral forms. Simple considerations place the
distribution of Compton-thick clouds at or within the optical broad line
region.Comment: Accepted for publication in Ap
Human Rights, Indigenous Peoples, and the Pursuit of Justice
There are three major problems with the use of the rights-based approach to tackle issues of Indigenous justice:
It privileges (the worldview of) the dominant legal culture;
It artificially restricts the conversation about causes of and solutions to problems of Indigenous justice; and
It masks the inherent tension between human rights and legal pluralism.
We explore the first of these problems in Part I by examining what is meant by a “rights-based approach,” how those ideas came into being, and how they differ from Indigenous conceptions. We address the second problem in Part II, which examines six representative U.S. cases and the patterns that can be derived from those cases. In Part III we turn to the third issue, which we operationalize in order to begin building possible solutions to the problem and possible alternate approaches to achieving justice for Indigenous people
Measuring the eccentricity of the Earth orbit with a nail and a piece of plywood
I describe how to obtain a rather good experimental determination of the
eccentricity of the Earth orbit, as well as the obliquity of the Earth rotation
axis, by measuring, over the course of a year, the elevation of the Sun as a
function of time during a day. With a very simple "instrument" consisting of an
elementary sundial, first-year students can carry out an appealing measurement
programme, learn important concepts in experimental physics, see concrete
applications of kinematics and changes of reference frames, and benefit from a
hands-on introduction to astronomy.Comment: 12 pages, 6 figure
Advanced crew procedures development techniques
The development of an operational computer program, the Procedures and Performance Program (PPP), is reported which provides a procedures recording and crew/vehicle performance monitoring capability. The PPP provides real time CRT displays and postrun hardcopy of procedures, difference procedures, performance, performance evaluation, and training script/training status data. During post-run, the program is designed to support evaluation through the reconstruction of displays to any point in time. A permanent record of the simulation exercise can be obtained via hardcopy output of the display data, and via magnetic tape transfer to the Generalized Documentation Processor (GDP). Reference procedures data may be transferred from the GDP to the PPP
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