卷 193, 编号 9 (2023)
Reviews of topical problems
Destruction of astronomical systems: theory and observations
摘要
The review is devoted to the analysis of the formation and evolution of streams of astrophysical objects of various natures. The stream components are destructible astronomical objects: comets, asteroids, planets, stars, star clusters, and gal„axies. Almost all of these streams are now observed. We discuss the conditions for the destruction of the original objects and for the formation and dissipation of these streams. We construct numerical models of streams generated by comets, asteroids, stars and their clusters, and galaxies in their clusters, and trace the evolution of these streams on the Hubble time scale.
Uspehi fizičeskih nauk. 2023;193(9):913-939
913-939
Generation of X-ray radiation in the inner regions of accretion disks around black holes, neutron stars, and white dwarfs
摘要
The most important temporal and spectral characteristics of X-ray radiation arising near black holes, neutron stars, and white dwarfs in the presence of matter accreting from the disk that surrounds the compact object are reviewed. It is shown how these characteristics are related to the physical parameters of these systems. A key characteristic of X-ray radiation is photon index $\Gamma$, defined as the slope of the emission spectrum in the energy range of 0.5–500 keV. If the compact object of a binary is a black hole, the X-ray radiation features saturation of the photon index (with increasing accretion rate), its value is ranging from 2 to 3. A correlation between $\Gamma$ and the quasi-periodic oscillation frequency, $\nu _QPO$, is revealed in these systems, which can be employed to independently determine the black hole mass using scaling method. The developed model of radiation transfer is now the basis of a scaling method which provides an independent estimate of mass also in the case of a supermassive black hole. The generated X-ray spectrum can be presented in a wide energy range as a combination of thermal, Comptonized, and Gaussian components that describe the emission lines. A model of radiative transfer in the vicinity of black holes and neutron stars can also explain the properties of the X-ray emission when the compact object is a white dwarf. The example of four dwarf novae, U Gem, SS Cyg, VW Hyi, and SS Aur, is used to show that the continuum of the X-ray spectrum of nonmagnetic cataclysmic variables can be described as a result of the Comptonization of soft photons on hot electrons of the accretion cloud that surrounds the white dwarf.
Uspehi fizičeskih nauk. 2023;193(9):940-970
940-970
Problems of parameterization of the radiation block in physical and mathematical climate models and the possibility of their solution
摘要
The problems associated with the failure to take into account periodic long-term and interannual changes in incoming solar radiation by latitudes and seasons, as well as long-term changes in the intensity of radiative heat transfer in the parameterization of the radiation block of physical and mathematical climate models, are shown. Existing problems with the radiation block parameterization limit the possibilities of modeling climate and forecasting its changes. To solve the problems, a review of Earth's insolation data with different time resolutions available for parameterization is presented.
Uspehi fizičeskih nauk. 2023;193(9):971-988
971-988
Physics of our days
Low-frequency oscillations in the direct osmotic process in a membrane with nanosized pores
摘要
The existence of low-frequency oscillations (1–10 Hz) in some modes of membrane processes (reverse osmosis, electroosmosis, bioosmotic phenomena, and fuel cells) has long been known. Although oscillations are only an accompanying effect of osmotic processes in membranes, many researchers noted such phenomena in their studies. We were the first to discover pressure fluctuations in an osmotic cell during direct osmosis. In the above osmotic processes, there is a significant impact of external factors (e.g., a superimposed external electric field) — but there are no such factors in the process of direct osmosis, allowing us to assert that oscillations are a consequence of the intrinsic properties of the membrane and the transport of water into the cell that occurs in it, which will allow a better understanding of the mechanisms of the processes in the membrane.
Uspehi fizičeskih nauk. 2023;193(9):989-993
989-993
Instruments and methods of investigation
Method of thermal desorption study of hydrogen states in carbon materials and nanomaterials
摘要
An efficient technique for processing, analyzing, and interpreting thermal desorption spectra (TDSs) of hydrogen in carbon materials and nanomaterials obtained using a single heating rate is developed, which makes it possible to study various states of hydrogen and determine the characteristics corresponding to them, including the rate constants and activation energies of desorption processes. The method is no less informative, but much less laborious from the experimental point of view, than the generally accepted (to determine such characteristics) Kissinger method, which requires using several heating rates and has strict limits on applicability. The developed technique is based on approximating the hydrogen TDS by Gaussians and processing their peaks in the approximation of first and second order reactions. The technique includes the use of nonstandard criteria of ‘likelihood’ and/or ‘physicality’ of the results, as well as verification and/or refinement of the results by numerical modeling methods that allow approximating TDSs not by Gaussians but by curves corresponding to first or second order reactions.
Uspehi fizičeskih nauk. 2023;193(9):994-1000
994-1000
New approaches to three-dimensional dislocation reconstruction in silicon from X-ray topo-tomography data
摘要
We present the results of processing the diffraction patterns of dislocation half-loops in Si(111) silicon single crystal, which were recorded by X-ray topo-tomography (XTT) at the European Synchrotron Radiation Facility (ESRF). An algorithm for preprocessing two-dimensional images by automatic noise filtering was proposed and solution reliability criteria were developed, which enabled a significant improvement in the quality of three-dimensional reconstruction of the spatial distribution of the defects under study. The experimental patterns were compared with those simulated numerically using the solution of Takagi equations. This approach made it possible not only to determine the geometry of the defects but also to derive information about the Burgers vector.
Uspehi fizičeskih nauk. 2023;193(9):1001-1009
1001-1009
Methodological notes
Isolation of the field component formed by a given beam of rays at the aperture of a receiving antenna in an inhomogeneous environment
摘要
A generalization of the classical procedure for forming a receiving antenna beam in a homogeneous space to the case of an inhomogeneous medium is discussed. In free space, this procedure isolates the component of the registered field, which represents the contribution of a beam of parallel rays. In an inhomogeneous medium, the procedure should isolate the contribution of a beam of rays, which, as a rule, are not parallel. The generalization is carried out on the basis of the transition from the traditional representation of the registered field in the form of a superposition of plane waves to the coherent state expansion of the field borrowed from quantum mechanics. The general approach is illustrated using the example of the lobe formation of a vertical receiving antenna in an underwater acoustic waveguide.
Uspehi fizičeskih nauk. 2023;193(9):1010-1020
1010-1020
Bibliography
New books on physics and related sciences: September 2023
Uspehi fizičeskih nauk. 2023;193(9):1021-1022
1021-1022
Physics news on the Internet: September 2023
Uspehi fizičeskih nauk. 2023;193(9):1023-1024
1023-1024