Configuration of the global magnetic field in AGN parsec-scale jets

The magnetic field plays a significant role in the phenomenon of highly collimated jets of active galactic nuclei (AGN). Relativistic effects prevent the direct reconstruction of the magnetic field direction as transverse to electric vectors on radio maps. We determined the topology of the \textbf{B}-field by modeling the transverse distributions of the total and linearly polarized intensity, polarization degree, and deviation of the polarization direction from the local jet axis and by further comparison with observational data. We consider (i) a helical field with a different twist angle; (ii) a toroidal field on the jet axis surrounded by a sheath with a longitudinal field. In the latter scenario, we consider different sheath thickness relative to the spine. We assumed the sheath velocity is equal to or less than that of the spine. The relativistic effects have been considered for a general case, under which the axis and velocity vector of the jet and radial directions do not coincide. Our simulations reproduce the main features of the observed transverse profiles of polarization characteristics in parsec-scale AGN jets. The model transverse distribution shapes of the polarization properties are found to be strongly influenced by kinematic and geometric parameters of an outflow. We demonstrated it for three AGNs having different but typical polarization patterns revealed on radio maps. For each of these objects, we identified the model parameters, which provide a qualitative correspondence of theoretical profiles with those obtained from observations, indicating that the \textbf{B}-field is strongly ordered on parsec scales.Comment: 16 pages, 11 figures, 2 table

Frequency of Cytokine Gene Polymorphism in Full-Term Newborns with Hypoxic Events

Background. An infant brain damage is an extremely urgent problem, this pathology is difficult to prevent, and subsequently it manifests itself with a variety of neurological consequences. Various mechanisms are involved in neurodamage; cytokines, as well as genes that control their activity, are under a great concern today. However, there is little data about their role as predictors of the brain damage among children after hypoxia. Aim of the research. To identify the frequency of cytokine gene polymorphism: interleukin (IL)-1β(C-511T), IL-1β(C3953T), IL-4(C589T), IL-6(C174G), IL-10(C819T), IL-10(G1082A) among newborns with hypoxic events. Materials and methods. The study involved 128 full-term newborn patients with hypoxic events: the first group (n = 48) included newborns who experienced chronic intrauterine hypoxia (CVH), the second group (n = 80) included newborns born in asphyxiation. Control group (52) included babies born without asphyxia and not suffering from CVH. A retrospective analysis of case-records was carried out. The material for molecular genetic analysis was DNA samples isolated from umbilical cord blood leukocytes using DNA Express Blood reagents (Scientific and Production Company LITECH, Moscow). Results. Compared to the control group (p = 0.03) children born in asphyxia had their T allele IL-1β (C-511T) prevailed. The group of newborn who had CVH had their TT genotype (p = 0.04) and the T IL-1β allele (C-511T) (p = 0.01) prevailed compared to the control group. In the same study group while studying the polymorphism of the IL-1β gene, the T allele (p = 0.03) at the point C3953T prevailed, in contrast to the control group. Conclusion. Due to the fact that cytokines are part of a reaction cascade leading to the secondary brain damage, under the action of hypoxia, it was found that among newborns undergoing asphyxia and chronic intrauterine hypoxia the increased frequencies of carriage of IL-1β-511TT and IL-1β-3953TT genotypes, and IL-1β-511T and IL-1β-3953T alleles increase the risk of neurodamage

TXS 0128+554: A Young Gamma-Ray Emitting AGN With Episodic Jet Activity

We have carried out a Chandra X-ray and multi-frequency radio VLBA study of the AGN TXS 0128+554, which is associated with the Fermi gamma-ray source 4FGL J0131.2+5547. The AGN is unresolved in a target 19.3 ks Chandra image, and its spectrum is well fit by a simple absorbed power law model, with no distinguishable spectral features. Its relatively soft X-ray spectrum compared to other CSOs may be indicative of a thermal emission component, for which we were able to obtain an upper temperature limit of kT = 0.08 keV. The compact radio morphology and measured advance speed of 0.32c +- 0.07c indicate a kinematic age of only 82 y +- 17 y, placing TXS 0128+554 among the youngest members of the compact symmetric object (CSO) class. The lack of compact, inverted spectrum hotspots and an emission gap between the bright inner jet and outer radio lobe structure indicate that the jets have undergone episodic activity, and were re-launched a decade ago. The predicted gamma-ray emission from the lobes, based on an inverse Compton-emitting cocoon model, is three orders of magnitude below the observed Fermi LAT flux. A comparison to other Fermi-detected and non-Fermi detected CSOs with redshift z<0.1 indicates that the gamma-ray emission likely originates in the inner jet/core region, and that nearby, recently launched AGN jets are primary candidates for detection by the Fermi LAT instrument.Comment: 22 pages, 9 figures, 7 tables; accepted by ApJ; full electronic table 2 is available from the preprint sourc

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

Multifrequency study of the gamma-ray flaring BL Lacertae object PKS 2233-148 in 2009-2012

We study the jet physics of the BL Lacertae object PKS 2233-148, making use of the synergy of observational data sets in the radio and gamma-ray energy domains. The four-epoch multifrequency (4-43 GHz) very-long-baseline array (VLBA) observations focused on the parsec-scale jet were triggered by a flare in gamma-rays registered by Fermi-LAT on 2010 April 23. We also used 15-GHz data from the OVRO 40-m telescope and MOJAVE VLBA monitoring programs. The jet shape of the source is found to be conical on scales probed by the VLBA observations, setting a lower limit of about 0.1 on its unknown redshift. Nuclear opacity is dominated by synchrotron self-absorption, with a wavelength-dependent core shift of r(core) ([mas]) approximate to 0.1 lambda[cm] mas co-aligned with the innermost jet direction. The turnover frequency of the synchrotron spectrum of the very-long-baseline interferometry core shifts towards lower frequencies as the flare propagates down the jet, and the speed of this propagation is significantly higher, about 1.2 mas yr(-1), than results from traditional kinematics based on tracking bright jet features. We have found indications that the gamma-ray production zone in the source is located at large distances, 10-20 pc, from a central engine, and could be associated with the stationary jet features. These findings favour synchrotron self-Compton, possibly in combination with external Compton scattering by infrared seed photons from a slow sheath of the jet, as the dominant high-energy emission mechanism of the source

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

Inverse Compton scattering of radiation of the central source as a mechanism for the formation of X-Ray radiation from kiloparsec jets of quasars

Уже около двадцати лет для интерпретации рентгеновского излучения килопарсековых джетов квазаров широко используется обратное комптоновское рассеяние реликтового излучения. Однако недавний анализ данных наблюдений космического телескопа Fermi-LAT показал неприменимость указанного предположения для джетов нескольких квазаров. Мы рассматриваем обратное комптоновское рассеяние фотонов центрального источника как возможный механизм образованияентгеновского излучения килопарсековых джетов для нескольких квазаров: PKS 0637–752, 3C 273, PKS 1510–089 и PKS 1045–188. Получены оценки угла с лучом зрения и скорости килопарсековых джетов. Предсказываемый поток излучения в гамма-диапазоне для всех объектов оказался ниже верхнего ограничения на поток от килопарсекового джета, полученного из данных наблюдений Fermi-LAT. Показано, что наше предположение о механизме образования рентгеновского излучения килопарсековых джетов согласуется со всеми имеющимися к настоящему времени данными многоволновых наблюдений.For the interpretation of X-ray radiation from kiloparsec jets of quasars, the inverse Compton scattering of the cosmic microwave background has been widely used for almost 20 years. A recent analysis of the Fermi-LAT observational data showed that this assumption is inapplicable for jets of several quasars. In this paper, we consider the inverse Compton scattering of photons from a central source as a possible mechanism for the formation of X-ray radiation from kiloparsec jets of the quasars PKS 0637–752, 3C 273, PKS 1510–089, and PKS 1045–188. Estimates of the angle between the line of sight and the velocity of kiloparsec jets are obtained. The predicted gamma-ray flux for all objects turned out to be below the upper limit on the flux from a kiloparsec jet obtained from the Fermi-LAT data. It is shown that our assumption about the mechanism of X-ray radiation from kiloparsec jets is consistent with all data of multiwavelength observations available to date

Enhanced empirical data for the fundamental diagram and the flow through bottlenecks

In recent years, several approaches for modelling pedestrian dynamics have been proposed and applied e.g. for design of egress routes. However, so far not much attention has been paid to their 'quantitative' validation. This unsatisfactory situation belongs amongst others on the uncertain and contradictory experimental data base. The fundamental diagram, i.e. the density-dependence of the flow or velocity, is probably the most important relation as it connects the basic parameter to describe the dynamic of crowds. But specifications in different handbooks as well as experimental measurements differ considerably. The same is true for the bottleneck flow. After a comprehensive review of the experimental data base we give an survey of a research project, including experiments with up to 250 persons performed under well controlled laboratory conditions. The trajectories of each person are measured in high precision to analyze the fundamental diagram and the flow through bottlenecks. The trajectories allow to study how the way of measurement influences the resulting relations. Surprisingly we found large deviation amongst the methods. These may be responsible for the deviation in the literature mentioned above. The results are of particular importance for the comparison of experimental data gained in different contexts and for the validation of models.Comment: A contribution to: Pedestrian and Evacuation Dynamics 2008 (Springer) 12 pages, 7 figure