46,819 research outputs found
Compact Binaries as Sources of Gravitational Radiation
With current terrestrial gravitational wave detectors working at initial
design sensitivities, and upgrades and space missions planned, it is likely
that in the next five to ten years gravitational radiation will be detected
directly from a variety of classes of objects. The most confidently expected of
these classes is compact binaries, involving neutron stars or black holes.
Detection of their coalescence, or their long-term orbits, has the potential to
inform us about the evolutionary history of compact binaries and possibly even
star formation over the past several billion years. We review what is currently
known about compact binaries as sources of gravitational radiation, as well as
the current uncertainties and what we expect to learn from future detections of
gravitational waves from these systems.Comment: To appear in the proceedings of the meeting "The Multicoloured
Landscape of Compact Objects and their Explosive Origins", Cefalu, Italy,
June 2006, to be published by AIP, Eds. L. Burderi et a
Beat-Frequency Models of Kilohertz QPOs
Kilohertz QPO sources are reasonably well-characterized observationally, but
many questions remain about the theoretical framework for these sources and the
consequent implications of the observations for disk physics, strong gravity,
and dense matter. We contrast the predictions and implications of the most
extensively studied class of kilohertz QPO models, the beat-frequency models,
with those of alternative classes of models. We also discuss the expected
impact of new observations of these sources with satellites such as Chandra,
XMM, and Constellation-X.Comment: 10 pages, invited paper at Bologna X-ray Astronomy 1999. To appear in
Astrophysical Letters and Communication
Electron Cotunneling into a Kondo Lattice
Motivated by recent experimental interest in tunneling into heavy electron
materials, we present a theory for electron tunneling into a Kondo lattice. The
passage of an electron into the Kondo lattice is accompanied by a simultaneous
spin flip of the localized moments via cotunneling mechanism. We compute the
tunneling current with the large- mean field theory. In the absence of
disorder, differential tunneling conductance exhibits two peaks separated by
the hybridization gap. Disorder effects lead to the smearing of the gap
resulting in a Fano lineshape.Comment: 4 pages, 2 eps figure
Generation of orthogonal boundary-fitted coordinate systems
A method is presented for computing orthogonal boundary fitted coordinate systems for geometries with coordinate distributions specified on all boundaries. The system which has found most extensive use in generating boundary fitted grids is made up of Poisson equations, of which the functions P and Q provide a means for controlling the spacing and density of grid lines in the coordinate system. While questions remain concerning the existence and uniqueness of orthogonal systems, the generating method presented adds to the available, useful techniques for constructing these systems
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