2,941 research outputs found
Group analysis and renormgroup symmetries
An original regular approach to constructing special type symmetries for
boundary value problems, namely renormgroup symmetries, is presented. Different
methods of calculating these symmetries, based on modern group analysis are
described. Application of the approach to boundary value problems is
demonstrated with the help of a simple mathematical model.Comment: 17 pages, RevTeX LATeX file, to appear in Journal of Mathematical
Physic
Radio emission evolution of nonstationary sources in the Hedgehog model
Correlations are obtained for numerical calculation of flux F sub v and polarized radiation intensity of a cloud of arbitrary geometry, consisting of ultrarelativistic electrons that dissipate in a radial magnetic field of the nucleus at a random angle to the observer. It is possible that some of the variable extragalactic objects that were previously described by the Shklovskiy model are young formations in the examined model. Radio astronomical observations would permit a determination of their distance, age, and lifetime
Radiation Pressure Quantization
Kepler's observation of comets tails initiated the research on the radiation
pressure of celestial objects and 250 years later they found new incarnation
after the Maxwell's equations were formulated to describe a plethora of
light-matter coupling phenomena. Further, quantum mechanics gave birth to the
photon drag effect. Here, we predict a novel universal phenomenon which can be
referred to as quantization of the radiation pressure. We develop a microscopic
theory of this effect which can be applied to a general system containing
Bose-Einstein-condensed particles, which possess an internal structure of
quantum states. By analyzing the response of the system to an external
electromagnetic field we find that such drag results in a flux of particles
constituting both the condensate and the excited states. We show that in the
presence of the condensed phase, the response of the system becomes quantized
which manifests itself in a step-like behavior of the particle flux as a
function of electromagnetic field frequency with the elementary quantum
determined by the internal energy structure of the particles.Comment: Manuscript: 4 pages, 3 figure
Observational evidence for the origin of high-energy neutrinos in parsec-scale nuclei of radio-bright active galaxies
Observational information on high-energy astrophysical neutrinos is being
continuously collected by the IceCube observatory. However, the sources of
neutrinos are still unknown. In this study, we use radio very-long-baseline
interferometry (VLBI) data for a complete VLBI-flux-density limited sample of
active galactic nuclei (AGN). We address the problem of the origin of
astrophysical neutrinos with energies above 200 TeV in a statistical manner. It
is found that AGN positionally associated with IceCube events have typically
stronger parsec-scale cores than the rest of the sample. The post-trial
probability of a chance coincidence is 0.2%. We select the four strongest AGN
as highly probable associations: 3C 279, NRAO 530, PKS 1741-038, and PKS
2145+067. Moreover, we find an increase of radio emission at frequencies above
10 GHz around neutrino arrival times for several other VLBI-selected AGN on the
basis of RATAN-600 monitoring. The most pronounced example of such behavior is
PKS 1502+106. We conclude that AGN with bright Doppler-boosted jets constitute
an important population of neutrino sources. High-energy neutrinos are produced
in their central parsec-scale regions, probably in proton-photon interactions
at or around the accretion disk. Radio-bright AGN that are likely associated
with neutrinos have very diverse gamma-ray properties suggesting that
gamma-rays and neutrinos may be produced in different regions of AGN and not
directly related. A small viewing angle of the jet-disk axis is, however,
required to detect either of them.Comment: 19 pages, 5 figures, 3 tables; accepted to ApJ; v2: extended
discussion, added a figure and electronic table; v3: fixed typo in a source
nam
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