Measurement of the Integrated Faraday Rotations of BL Lac Objects

We present the results of multi-frequency polarization VLA observations of radio sources from the complete sample of northern, radio-bright BL Lac objects compiled by H. Kuhr and G. Schmidt. These were used to determine the integrated rotation measures of 18 objects, 15 of which had never been measured previously, which hindered analysis of the intrinsic polarization properties of objects in the complete sample. These measurements make it possible to correct the observed orientations of the linear polarizations of these sources for the effect of Faraday rotation. The most probable origin for Faraday rotation in these objects is the Galactic interstellar medium. The results presented complete measurements of the integrated rotation measures for all 34 sources in the complete sample of BL Lac objects.Comment: 9 pages, 7 figure

Freely decaying weak turbulence for sea surface gravity waves

We study numerically the generation of power laws in the framework of weak turbulence theory for surface gravity waves in deep water. Starting from a random wave field, we let the system evolve numerically according to the nonlinear Euler equations for gravity waves in infinitely deep water. In agreement with the theory of Zakharov and Filonenko, we find the formation of a power spectrum characterized by a power law of the form of $|{\bf k}|^{-2.5}$.Comment: 4 pages, 3 figure

NATURE OF INTERLAYER BONDS IN TWO-DIMENSIONAL DITELURIDES

In our work, by using first-principles calculations we perform a systematic study of the interlayer bonds and charge redistribution of ditelurides (NiTe2, PdTe2, PtTe2). Our results demonstrate, that bonds in ditelurides can be assiosiated with so-called dative chemical bonds between layers.This work was supported by the Russian Science Foundation Grant 21-72-10136

Structural phase transitions in VSe2: Energetics, electronic structure and magnetism

First principles calculations of the magnetic and electronic properties of VSe2 describing the transition between two structural phases (H,T) were performed. The results of the calculations evidence a rather low energy barrier (0.60 eV for the monolayer) for the transition between the phases. The energy required for the deviation of a Se atom or whole layer of selenium atoms by a small angle of up to 10° from their initial positions is also rather low, 0.32 and 0.19 eV/Se, respectively. The changes in the band structure of VSe2 caused by these motions of Se atoms should be taken into account for analysis of the experimental data. Simulations of the strain effects suggest that the experimentally observed T phase of the VSe2 monolayer is the ground state due to substrate-induced strain. Calculations of the difference in the total energies of the ferromagnetic and antiferromagnetic configurations evidence that the ferromagnetic configuration is the ground state of the system for all stable and intermediate atomic structures. Calculated phonon dispersions suggest a visible influence of the magnetic configurations on the vibrational properties. This journal is © the Owner Societies

USING THE MODERN THEORY OF MAGNETIC SUSCEPTIBILITY APPROACH TO DESCRIBE THE LOW-DIMENSIONAL MATERIALS: TWO-DIMENSIONAL ANTIMONY

Antimonene is a recently discovered two-dimensional material with high environmental stability and great electronic properties. We report on a computational study of magnetic response of antimonene focusing on the effect of gate voltage, playing an important role due to the structure of material.This work was supported by the Russian Science Foundation Grant № 21-12-00338

The July 2010 outburst of the NLS1 PMN J0948+0022

We report about the multiwavelength campaign on the Narrow-Line Seyfert 1 (NLS1) Galaxy PMN J0948+0022 (z = 0.5846) performed in 2010 July-September and triggered by high activity as measured by Fermi/LAT. The peak luminosity in the 0.1-100 GeV energy band exceeded, for the first time in this type of source, the value of 10^48 erg/s, a level comparable to the most powerful blazars. The comparison of the spectral energy distribution of the NLS1 PMN J0948+0022 with that of a typical blazar - like 3C 273 - shows that the power emitted at gamma rays is extreme.Comment: 2011 Fermi Symposium proceedings - eConf C11050

Faraday rotation in the MOJAVE blazars: 3C 273 a case study

Radio polarimetric observations of Active Galactic Nuclei can reveal the magnetic field structure in the parsec-scale jets of these sources. We have observed the gamma-ray blazar 3C 273 as part of our multi-frequency survey with the Very Long Baseline Array to study Faraday rotation in a large sample of jets. Our observations re-confirm the transverse rotation measure gradient in 3C 273. For the first time the gradient is seen to cross zero which is further indication for a helical magnetic field and spine-sheath structure in the jet. We believe the difference to previous epochs is due to a different part of the jet being illuminated in our observations.Comment: 6 pages, 3 figures. To appear in the proceedings of "Beamed and Unbeamed Gamma-rays from Galaxies", held in Muonio, Finland, April 11-15, 2011. Journal of Physics: Conference Serie

Developing a New Effective Magnetic Model of Fe3GeTe2 Based on AB-Initio Calculations

In our work we propose a new effective magnetic model for two-dimensional van der Waals ferromagnet Fe3GeTe2. To prove its correctness we conducted ab-initio calculations as well as compared Curie temperatures using Monte Carlo simulations with the obtained parameters.This work was supported by the Russian Science Foundation, Grant No. 21-72-10136

Multi-epoch parsec-scale observations of the blazar PKS 1510-089

(Abridged) We investigate the flux density variability and changes in the parsec-scale radio structure of the flat spectrum radio quasar PKS 1510-089. This source was target of multi-epoch VLBI and Space-VLBI observations at 4.8, 8.4 and 22 GHz carried out between 1999 and 2001. The comparison of the parsec-scale structure observed at different epochs shows the presence of a non-stationary jet feature moving with a superluminal apparent velocity of 16.2c+-0.7c. Over three epochs at 8.4 GHz during this period the core flux density varies of about 50%, while the scatter in the jet flux density is within 10%. The polarization percentage of both core and jet components significantly change from 2 to 9 per cent, while the polarization angle of the core shows an abrupt change of about 90 degrees becoming roughly perpendicular to the jet direction, consistent with a change in the opacity. To complete the picture of the physical processes at work, we complemented our observations with multi-epoch VLBA data at 15 GHz from the MOJAVE programme spanning a time baseline from 1995 to 2010. Since 1995 jet components are ejected roughly once per year with the same position angle and an apparent speed between 15c and 20c, indicating that no jet precession is taking place on a timescale longer than a decade in our frame. The variability of the total intensity flux density together with variations in the polarization properties may be explained assuming either a change between the optically-thick and -thin regimes produced by a shock that varies the opacity, or a highly ordered magnetic field produced by the compression of the relativistic plasma by a shock propagating along the jet. Taking into account the high gamma-ray emission observed from this source by the AGILE and Fermi satellites we investigated the connection between the radio and gamma-ray activity during 2007-2010.Comment: 12 pages, 13 figures; accepted for publication in MNRA