The connection between the radio jet and the gamma-ray emission in the radio galaxy 3C 120

We present the analysis of the radio jet evolution of the radio galaxy 3C 120 during a period of prolonged gamma-ray activity detected by the Fermi satellite between December 2012 and October 2014. We find a clear connection between the gamma-ray and radio emission, such that every period of gamma-ray activity is accompanied by the flaring of the mm-VLBI core and subsequent ejection of a new superluminal component. However, not all ejections of components are associated with gamma-ray events detectable by Fermi. Clear gamma-ray detections are obtained only when components are moving in a direction closer to our line of sight.This suggests that the observed gamma-ray emission depends not only on the interaction of moving components with the mm-VLBI core, but also on their orientation with respect to the observer. Timing of the gamma-ray detections and ejection of superluminal components locate the gamma-ray production to within almost 0.13 pc from the mm-VLBI core, which was previously estimated to lie about 0.24 pc from the central black hole. This corresponds to about twice the estimated extension of the broad line region, limiting the external photon field and therefore suggesting synchrotron self Compton as the most probable mechanism for the production of the gamma-ray emission. Alternatively, the interaction of components with the jet sheath can provide the necessary photon field to produced the observed gamma-rays by Compton scattering.Comment: Already accepted for publication in The Astrophysical Journa

Multiwavelength observations of the blazar BL Lacertae: a new fast TeV γ-ray flare

Proceedings of the 35th International Cosmic Ray Conference (ICRC 2017), Busan (South Korea). Published in Proceeding of Science.Observations of fast TeV γ-ray flares from blazars reveal the extreme compactness of emitting regions in blazar jets. Combined with very-long-baseline radio interferometry measurements, they probe the structure and emission mechanism of the jet. We report on a fast TeV γ-ray flare from BL Lacertae observed by VERITAS, with a rise time of about 2.3 hours and a decay time of about 36 minutes. The peak flux at >200 GeV measured with the 4-minute binned light curve is (4.2±0.6)×10−6photonsm−2s−1, or ∼180% the Crab Nebula flux. Variability in GeV γ-ray, X-ray, and optical flux, as well as in optical and radio polarization was observed around the time of the TeV γ-ray flare. A possible superluminal knot was identified in the VLBA observations at 43 GHz. The flare constrains the size of the emitting region, and is consistent with several theoretical models with stationary shocks

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

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

Turbulent Thermalization

We study, analytically and with lattice simulations, the decay of coherent field oscillations and the subsequent thermalization of the resulting stochastic classical wave-field. The problem of reheating of the Universe after inflation constitutes our prime motivation and application of the results. We identify three different stages of these processes. During the initial stage of ``parametric resonance'', only a small fraction of the initial inflaton energy is transferred to fluctuations in the physically relevant case of sufficiently large couplings. A major fraction is transfered in the prompt regime of driven turbulence. The subsequent long stage of thermalization classifies as free turbulence. During the turbulent stages, the evolution of particle distribution functions is self-similar. We show that wave kinetic theory successfully describes the late stages of our lattice calculation. Our analytical results are general and give estimates of reheating time and temperature in terms of coupling constants and initial inflaton amplitude.Comment: 27 pages, 13 figure

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

Benign breast tumors and risk factors for their development

The purpose of the review was to evaluate and analyze the literature data on the presented problem in recent years.Цель обзора – оценка и анализ литературных данных по представленной проблеме за последние годы