We examine the possibility of the active galactic nucleus (AGN) obscuration by dusty gas clouds that spurt out from circumnuclear starburst regions. For the purpose, the dynamical evolution of gas clouds is pursued, including the effects of radiation forces by an AGN as well as a starburst. Here, we solve the radiative transfer equations for clouds, taking into consideration the growth of cloud...

The nuclei of active galaxies harbor massive young stars, an accreting central black hole, or both. In order to determine the physical conditions that pertain to molecular gas close to the sources of radiation, numerical models are constructed. These models iteratively determine the thermal and chemical balance of molecular gas that is exposed to X-rays (1-100 keV) and far-ultraviolet radiation...

The scattering of photons off photons at the one-loop level is investigated. We give a short review of the weak field limit, as given by the first order term in the series expansion of the Heisenberg– Euler Lagrangian. The dispersion relation for a photon in a radiation gas is presented. Based on this, a wave kinetic equation and a set of fluid equations is formulated. These equations describe ...

We show that static and oscillating photon bubbles can be excited by diffused light in the laser cooled matter confined in a magneto-optical trap. The bubble instability is due to the coupling between the radiation field and the mean field oscillations of the ultracold gas, and it can provide a source for low frequency turbulence. We consider a diffusion-dominated regime, which can be described...

We have derived the albedo (a) and phase function asymmetry factor (g) of interstellar dust grains at 11008 using archival Voyager observations of diffuse radiation in Ophiuchus. We have found that the grains are highly forwardscattering, with g 1⁄4 0:55 0:25 and a 1⁄4 0:40 0:10. Even though most of the gas in this direction is in the Ophiuchus molecular cloud, the diffuse FUV radiation is almo...

Pronounced resonant absorption and frequency dispersion associated with an excitation of collective 2D plasmons have been observed in terahertz (0.5-4THz) transmission spectra of grating-gate 2D electron gas AlGaN/GaN HEMT (high electron mobility transistor) structures at cryogenic temperatures. The resonance frequencies correspond to plasmons with wavevectors equal to the reciprocal-lattice ve...

This paper studies the problems of mathematical description of physical processes in open non-equilibrium atmosphere. It is proposed that the mathematical description should be based on the idea that properties of an open system are determined by the properties of its elements and external constraints. It is also explained why atmosphere should be represented by an open non-equilibrium system o...

A new mechanism for generating coherent radiation from a laser-ionized gas-filled capacitor array is presented. This scheme directly converts a static electric field of wave number k0 into coherent radiation pulses. The physical mechanism is analogous to photon acceleration in plasma waves, and in this sense, photons are accelerated from zero frequency (zero energy) to a frequency ωp2/2k0c. The...

Background: Nitrous oxide (N2O) is a greenhouse gas that is a very small portion of the nitrogen cycle, but is environmentally damaging at low levels. In the lower atmosphere, N2O absorbs infrared radiation in spectra not absorbed by other common greenhouse gases, such as carbon dioxide. Because of N2O’s unique spectral absorption range, each molecule absorbs 200 times as much outgoing radiatio...