8,797 research outputs found
Relativistic Dynamos in Magnetospheres of Rotating Compact Objects
The kinematic evolution of axisymmetric magnetic fields in rotating
magnetospheres of relativistic compact objects is analytically studied, based
on relativistic Ohm's law in stationary axisymmetric geometry. By neglecting
the poloidal flows of plasma in simplified magnetospheric models, we discuss
self-excited dynamos due to the frame-dragging effect (originally pointed out
by Khanna & Camenzind), and we propose alternative processes to generate
axisymmetric magnetic fields against ohmic dissipation. The first process
(which may be called induced excitation) is caused by the help of a background
uniform magnetic field in addition to the dragging of inertial frames. It is
shown that excited multipolar components of poloidal and azimuthal fields are
sustained as stationary modes, and outgoing Poynting flux converges toward the
rotation axis. The second one is self-excited dynamo through azimuthal
convection current, which is found to be effective if plasma rotation becomes
highly relativistic with a sharp gradient in the angular velocity. In this case
no frame-dragging effect is needed, and the coupling between charge separation
and plasma rotation becomes important. We discuss briefly the results in
relation to active phenomena in the relativistic magnetospheres.Comment: 16 pages, AASLaTeX macros v4.
Laboratory infrared studies relevant to Io: A satellite to the planet Jupiter
To explain the unidentified spectral features of Io, as obtained by the Voyager infrared spectrometer experiment, the infrared absorption spectra of a number of stable sulfur and oxygen compounds was measured and compared to the Voyager data. Based on the reference absorption bands of Na2SO4 and possibly SO2, the infrared data on Io in the region 700 to 200 per cm appear to represent an emission spectrum. Given the strong evidence for an oxidized crustal environment and the presence of sodium in the Io torus, the absorption spectra of the tested materials support the probability of Na2SO4 occurrence on Io
Late-time Kerr tails: generic and non-generic initial data sets, "up" modes, and superposition
Three interrelated questions concerning Kerr spacetime late-time scalar-field
tails are considered numerically, specifically the evolutions of generic and
non-generic initial data sets, the excitation of "up" modes, and the resolution
of an apparent paradox related to the superposition principle. We propose to
generalize the Barack-Ori formula for the decay rate of any tail multipole
given a generic initial data set, to the contribution of any initial multipole
mode. Our proposal leads to a much simpler expression for the late-time power
law index. Specifically, we propose that the late-time decay rate of the
spherical harmonic multipole moment because of an initial
multipole is independent of the azimuthal number , and is
given by , where for and
for . We also show explicitly that the angular symmetry group of
a multipole does not determine its late-time decay rate.Comment: 12 pages, 13 figures, 4 tables. Substantially revised manuscrip
Crystalline sulfur dioxide: Crystal field splittings, absolute band intensities and complex refractive indices derived from infrared spectra
The infrared absorption spectra of thin crystalline films of sulfur dioxide at 90 K are reported in the 2700 to 450/cm region. The observed multiplicity of the spectral features in the regions of fundamentals is attributed to factor group splittings of the modes in a biaxial crystal lattice and the naturally present minor S-34, S-36, and O-18 isotopic species. Complex refractive indices determined by an iterative Kramers-Kronig analysis of the extinction data, and absolute band strengths derived from them, are also reported in this region
Analysis of direct CP violation in decays
We investigate the possibility of observing the direct CP violation in the
decay modes and within the Standard Model.
Including the contributions arising from the tree, annihilation, QCD as well as
electroweak penguins with both time- and space-like components, we find that
the direct CP asymmetry in is very small % but
in decay it can be as large as 4%. Approximately
charged mesons are required to experimentally observe the CP asymmetry
parameter for the later case. Since this is easily accessible with the
currently running B factories, the decay mode may be pursued
to look for CP violation.Comment: Latex, 14 page
Absorption and resonance Raman spectra of Pb2, Pb3 and Pb4 in xenon matrices
Lead metal was vaporized and trapped in solid xenon at 12K. Electronic absorption and resonance Raman spectra were recorded of the resulting matrix, which was shown to contain Pb2, Pb3, and possibly Pb4 molecular species. The vibrational frequency for Pb2 is determined to be 108/cm for the ground state, with a dissociation energy of 82000/cm. Ad3h symmetry is indicated for the Pb3 species, with nu sub 1=117/cm and nu sub 2 = 96 /cm. The existence of Pb4 is suggested by a fundamental and overtone of 111/cm spacing
Landau Ginzburg Theory and Nuclear Matter at Finite Temperature
Based on recent studies of the temperature dependence of the energy and
specific heat of liquid nuclear matter, a phase transition is suggested at a
temperature MeV. We apply Landau Ginzburg theory to this transition
and determine the behaviour of the energy and specific heat close to the
critical temperature in the condensed phase.Comment: 10 pages, Revte
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