568 research outputs found
Behaviour of the Blazar CTA 102 during two giant outbursts
Blazar CTA 102 underwent exceptional optical and high-energy outbursts in 2012 and 2016-2017. We analyze its behaviour during these events, focusing on polarimetry as a tool that allows us to trace changes in the physical conditions and geometric configuration of the emission source close to the central black hole. We also use Fermi gamma-ray data in conjunction with optical photometry in an effort to localize the origin of the outbursts.AST-1615796 - Boston Universit
Hole-hole interaction in a strained InGaAs two dimensional system
The interaction correction to the conductivity of 2D hole gas in strained
GaAs/InGaAs/GaAs quantum well structures was studied. It is shown
that the Zeeman splitting, spin relaxation and ballistic contribution should be
taking into account for reliable determination of the Fermi-liquid constant
. The proper consideration of these effects allows us to describe
both th temperature and magnetic field dependences of the conductivity and find
the value of .Comment: 7 pages, 6 figure
The role and importance of the cluster approach in the development of domestic tourism of the Russian Federation
© 2017. ASERS Publishing. All rights reserved. The relevance of the topic is determined by the fact that tourist's cluster plays an important role in the development of not only municipalities, regions of the Russian Federation, federal districts, but the country as a whole, solving social problems, including those that relate to the creation of jobs, the problems of improvement in the quality of domestic tourist's products and services and incensement in investment and tourist's potential of the regions and the country. The aim of the study of the role of clusters in the development of domestic tourism was a compilation of existing research approaches and results of original research in this field. The leading methods to solve this problem are the methods of systemic, economic and statistical analysis, quantitative and qualitative research. In support of the main provisions of the authors also relied on expert methods of obtaining and processing information. The article gives the basic theoretical and practical interpretation of the definition of tourist's cluster. The mechanisms and identified issues of state participation in the formation and development of the tourist cluster, based on the research methodology and practices, as well as authoring, compiled tools of state support for domestic tourism development. Article Submissions are of practical value to planners in the tourism sector, tourism administrations, marketing professionals of tourism enterprises
Interband mixing between two-dimensional states localized in a surface quantum well and heavy hole states of the valence band in narrow gap semiconductor
Theoretical calculations in the framework of Kane model have been carried out
in order to elucidate the role of interband mixing in forming the energy
spectrum of two-dimensional carriers, localized in a surface quantum well in
narrow gap semiconductor. Of interest was the mixing between the 2D states and
heavy hole states in the volume of semiconductor. It has been shown that the
interband mixing results in two effects: the broadening of 2D energy levels and
their shift, which are mostly pronounced for semiconductors with high doping
level. The interband mixing has been found to influence mostly the effective
mass of 2D carriers for large their concentration, whereas it slightly changes
the subband distribution in a wide concentration range.Comment: 12 pages (RevTEX) and 4 PostScript-figure
Diffusion and ballistic contributions of the interaction correction to the conductivity of a two-dimensional electron gas
The results of an experimental study of interaction quantum correction to the
conductivity of two-dimensional electron gas in AB semiconductor
quantum well heterostructures are presented for a wide range of
-parameter (), where is the transport
relaxation time. A comprehensive analysis of the magnetic field and temperature
dependences of the resistivity and the conductivity tensor components allows us
to separate the ballistic and diffusion parts of the correction. It is shown
that the ballistic part renormalizes in the main the electron mobility, whereas
the diffusion part contributes to the diagonal and does not to the off-diagonal
component of the conductivity tensor. We have experimentally found the values
of the Fermi-liquid parameters describing the electron-electron contribution to
the transport coefficients, which are found in a good agreement with the
theoretical results.Comment: 11 pages, 11 figure
A multi-wavelength polarimetric study of the blazar CTA 102 during a Gamma-ray flare in 2012
We perform a multi-wavelength polarimetric study of the quasar CTA 102 during
an extraordinarily bright -ray outburst detected by the {\it Fermi}
Large Area Telescope in September-October 2012 when the source reached a flux
of F photons cm s.
At the same time the source displayed an unprecedented optical and NIR
outburst. We study the evolution of the parsec scale jet with ultra-high
angular resolution through a sequence of 80 total and polarized intensity Very
Long Baseline Array images at 43 GHz, covering the observing period from June
2007 to June 2014. We find that the -ray outburst is coincident with
flares at all the other frequencies and is related to the passage of a new
superluminal knot through the radio core. The powerful -ray emission is
associated with a change in direction of the jet, which became oriented more
closely to our line of sight (1.2) during the ejection of
the knot and the -ray outburst. During the flare, the optical polarized
emission displays intra-day variability and a clear clockwise rotation of
EVPAs, which we associate with the path followed by the knot as it moves along
helical magnetic field lines, although a random walk of the EVPA caused by a
turbulent magnetic field cannot be ruled out. We locate the -ray
outburst a short distance downstream of the radio core, parsecs from the black
hole. This suggests that synchrotron self-Compton scattering of near-infrared
to ultraviolet photons is the probable mechanism for the -ray
production.Comment: Accepted for publication in The Astrophysical Journa
The Outburst of the Blazar AO 0235+164 in 2006 December: Shock-in-Jet Interpretation
We present the results of polarimetric ( band) and multicolor photometric
() observations of the blazar AO 0235+16 during an outburst in 2006
December. The data reveal a short timescale of variability (several hours),
which increases from optical to near-IR wavelengths; even shorter variations
are detected in polarization. The flux density correlates with the degree of
polarization, and at maximum degree of polarization the electric vector tends
to align with the parsec-scale jet direction. We find that a variable component
with a steady power-law spectral energy distribution and very high optical
polarization (30-50%) is responsible for the variability. We interpret these
properties of the blazar withina model of a transverse shock propagating down
the jet. In this case a small change in the viewing angle of the jet, by
, and a decrease in the shocked plasma compression by a factor of
1.5 are sufficient to account for the variability.Comment: 22 pages, 8 figures, accepted for Ap
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