42,727 research outputs found
Extragalactic radio source evolution under the dual-population unification scheme
We show that a dual-population unification scheme provides a successful
paradigm with which to describe the evolution and beaming of all bright
extragalactic radio sources. The paradigm consists of two intrinsic
radio-source populations, based on the two distinct radio-galaxy morphologies
of Fanaroff-Riley classes I and II. These represent the `unbeamed' or `side-on'
parent populations of steep radio spectra; the `beamed' source types including
flat-spectrum quasars and BL Lac objects, arise through the random alignment of
their radio-axis to our line-of-sight where Doppler-beaming of the relativistic
radio jets produces highly anisotropic radio emission.Comment: 18 pages & 18 postscript figures, accepted for publication in MNRA
The electromagnetic self-force on a charged spherical body slowly undergoing a small, temporary displacement from a position of rest
The self-force of classical electrodynamics on a charged "rigid" body of
radius R is evaluated analytically for the body undergoing a slow (i.e., with a
speed v<<c), slight (i.e., small compared to R), and temporary displacement
from an initial position of rest. The results are relevant to the
Bohr-Rosenfeld analysis of the measurability of the electromagnetic field,
which has been the subject of a recent controversy.Comment: REVTeX, 15 pages, 3 figures, accepted by J. Phys.
Local field effect as a function of pulse duration
In this note we give semiclassical consideration of the role of pulse
duration in observation of local field effects in the regime of optical
switching. We show that the main parameter governing local field influence is
the ratio of peak Rabi frequency corresponding to medium inversion and Lorentz
frequency of the medium. To obtain significant local field effect, this
parameter should be near unity that is valid only for long enough pulses. We
also discuss the role of relaxation and pulse shape in this processes.Comment: 4 pages, 3 figure
Charged coherent states related to su_{q}(2) covariance
A new kind of q-deformed charged coherent states is constructed in Fock space
of two-mode q-boson system with su_{q}(2) covariance and a resolution of unity
for these states is derived. We also present a simple way to obtain these
coherent states using state projection method.Comment: 7 pages. To appear in Modern Phyics Letter:
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