Dynamics of Vortex Pair in Radial Flow

The problem of vortex pair motion in two-dimensional plane radial flow is solved. Under certain conditions for flow parameters, the vortex pair can reverse its motion within a bounded region. The vortex-pair translational velocity decreases or increases after passing through the source/sink region, depending on whether the flow is diverging or converging, respectively. The rotational motion of two corotating vortexes in a quiescent environment transforms into motion along a logarithmic spiral in the presence of radial flow. The problem may have applications in astrophysics and geophysics.Comment: 13 pages, 9 figure

A Dipole Vortex Model of Obscuring Tori in Active Galaxy Nuclei

The torus concept as an essential structural component of active galactic nuclei (AGN) is generally accepted. Here, the situation is discussed when the torus "twisting" by the radiation or wind transforms it into a dipole toroidal vortex which in turn can be a source of matter replenishing the accretion disk. Thus emerging instability which can be responsible for quasar radiation flares accompanied by matter outbursts is also discussed. The "Matreshka" scheme for an obscuring vortex torus structure capable of explaining the AGN variability and evolution is proposed. The model parameters estimated numerically for the luminosity close to the Eddington limit agree well with the observations.Comment: 17 pages, 11 figures, version of this paper is published in Astronomy Report

Gravitational potential of a homogeneous circular torus: new approach

The integral expression for gravitational potential of a homogeneous circular torus composed of infinitely thin rings is obtained. Approximate expressions for torus potential in the outer and inner regions are found. In the outer region a torus potential is shown to be approximately equal to that of an infinitely thin ring of the same mass; it is valid up to the surface of the torus. It is shown in a first approximation, that the inner potential of the torus (inside a torus body) is a quadratic function of coordinates. The method of sewing together the inner and outer potentials is proposed. This method provided a continuous approximate solution for the potential and its derivatives, working throughout the region.Comment: 10 pages, 9 figures, 1 table; some misprints in formulae were correcte

Dynamical model of an obscuring clumpy torus in AGNs - I. Velocity and velocity dispersion maps for interpretation of ALMA observations

We have developed the dynamical model of a clumpy torus in an active galactic nucleus (AGN) and compared to recent The Atacama Large Millimeter Array (ALMA) observations. We present N-body simulations of a torus in the field of a supermassive black hole (SMBH), made of up to N = 105 gravitationally interacting clouds. As initial conditions, we choose random distributions of the orbital elements of the clouds with a cut-off in the inclination to mimic the presence of wind cones produced at the early AGN stage. When the torus reaches an equilibrium, it has a doughnut shape. We discuss the presence of box orbits. We have then constructed the velocity and velocity dispersion maps using the resulting distributions of the clouds at equilibrium. The effects of torus inclination and cloud sizes are duly analysed. We discuss the obscuration effects of the clouds using a ray tracing simulation matching the model maps to ALMA resolution. By comparing the model with the observational maps of NGC 1068, we find that the SMBH mass is M_\\text{smbh}=5\\times 10^6 \\, \\mathrm{M}_\\odot for the range of the torus inclination angles 45°-60°. We also construct the velocity dispersion maps for NGC 1326 and NGC 1672. They show that the peaks in the ALMA dispersion maps are related to the emission of the torus throat. Finally, we obtain the temperature distribution maps with parameters that correspond to our model velocity maps for NGC 1068. They show stratification in temperature distribution with the shape of the high-temperature region as in the VLTI/MIDI map

The impact of terahertz radiation on an extremophilic archaean Halorubrum saccharovorum proteome

Nonthermal effects of terahertz radiation on living objects are currently intensely studied, as more sources of this radiation type and devices employing it are being constructed. Terahertz radiation is increasingly used in security and inspection systems, medical and scientific appliances due to its low quant energy, which does not cause severe effects on organisms as other radiation types with higher quant energies do. The aim of this study was the identification of protein complexes participating in the response of the archaea Halorubrum saccharovorum H3 isolated from an extreme natural environment to terahertz radiation. We developed a microfluidic system for irradiation of bacterial and archaeal cultures with terahertz radiation and performed a 5-hour-long exposure of H. saccharovorum to terahertz radiation at a wavelength of 130 μm and a power density of 0.8 Wt per cm2 for 5 h. We identified under- or overexpressed proteins in response to terahertz radiation using 2D electrophoresis with subsequent MALDI-TOF mass spectrometry. A total of 16 differentially expressed protein fractions with at least 1.5-fold changes in expression level were detected. The obtained data suggest that Halorubrum cells respond to exposure to terahertz radiation by expression changes in gene products involved in translation regulation