The article evaluates the amplitude suppression for the relict gravitational waves with a frequency of
Hz due to their conversion into electromagnetic waves under the influence of a cosmological ...magnetic field during the era of radiation dominance (RD). At first, a system of equations was obtained for the joint propagation of gravitational and electromagnetic waves in an external magnetic field in the Friedmann–Lemaitre–Robertson–Walker metric and the interaction of electromagnetic waves with the primary plasma was taken into account. Then the resulting system is solved numerically in the approximation of a uniform cosmological magnetic field with a strength corresponding to the modern value of 1 nG (for the RD epoch the magnetic field strength increases as the inverse scale factor squared). Finally a conclusion was made about the insignificant influence of the considered conversion effect on the amplitude of long-wave relic gravitational waves.
Equation describing propagation of gravitational waves (GW) over arbitrary curved space-time background is analyzed. New terms, which are absent in the conventional homogeneous and isotropic ...Friedmann cosmology, are found. Some examples of realistic metric, where these new terms manifest themselves, are presented. Possible implications to very low frequency GW are briefly discussed.
The current situation in cosmology and particle physics, which are two closely related fields of fundamental physics, is unique. The Standard Model of particle physics excellently reproduces all ...existing experimental data except for neutrino oscillations. Similarly, the comparison of the standard cosmological model with astronomical observations indicates that we well understand the evolution of the Universe from its “birth” to the present. However, to understand mechanisms of numerous cosmological phenomena, it is certainly necessary to go beyond the Standard Model. These are primarily the problems of dark matter and dark energy, generation of the baryon asymmetry of the Universe, and the mechanism of inflation expansion. The problem of the appearance of cosmic magnetic fields and the recent problem of the existence of massive black holes whose number in the Universe is much larger than the expected values are among less known, but also very important problems in conventional cosmology and astrophysics. To understand and possibly solve these problems, it is very important to provide deep insight into the Universe and to obtain data on physical processes at the early stages of the cosmological evolution. Multi-messenger observations involving all possible messengers (“windows”) provide a powerful tool for this. In addition to conventional detection of electromagnetic radiation in all bands and all types of cosmic rays, the observations of gravitational waves have recently opened a new window. A complex analysis of information obtained from various astronomical data has been performed in our works supported by the Russian Science Foundation (project no. 20-42-09010 “Opening of New Windows to the Early Universe by Means of Multi-Messenger Astronomy”). In particular, the characteristics of cosmic magnetic fields and possible mechanisms of their appearance have been studied and the observed manifestations of primary black holes have been examined using the data on gravitational waves observed at the LIGO/Virgo/KAGRA interferometers.
Samples of ash prepared from oat husks and products of their chemical and enzymatic processing in the bacterial nanocellulose production cycle were studied. Their elemental composition and content of ...the main substance, silicon dioxide, were determined, and the IR spectra and X-ray diffraction patterns were taken. The purest silica was prepared from the dry residue after enzymatic hydrolysis of the product of nitric acid treatment of oat husks, which allows comprehensive use of organic and inorganic components of the vegetable raw material.
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We have demonstrated the possibility of preparing nanostructured, X-ray amorphous sodium aluminosilicate with a specific surface area of 364 m
2
/g using an alkaline rice straw hydrolysate. Its Cs
...+
sorption properties have been studied under static conditions in solutions with various salt compositions (seawater and nitrate solutions).
Sodium and potassium aluminosilicates samples are synthesized from solutions formed via the alkaline hydrolysis of rice straw. The fabricated samples are characterized by means of X-ray diffraction ...analysis and IR-spectroscopy, and their elemental composition, particle morphology, specific surface area, and thermal properties are determined. The sorption properties of the synthesized aluminosilicates with respect to Cs
+
ions are investigated under static conditions. Kinetic curves and sorption isotherms are provided and a sorption kinetic model is described.
Using rice straw of various varieties of the Far Eastern selection as a source of silicon, a number of samples of sodium aluminosilicates with a Si:Al ratio from 1.02 to 1.56 were synthesized. For ...the obtained samples, the elemental and phase composition was found, the thermal properties were investigated. The morphology of aluminosilicates was studied: the particle size varies from 0.2 to 50 μm with a maximum distribution of about 10 μm, the specific surface area is 364 m2/g. The acid-base properties of the surface of aluminosilicates are characterized by pH-metry methods and the Hammett indicator method, the nature of the distribution of adsorption centers on the surface is established. The sorption capacity of the obtained samples, determined with respect to methylene blue (MB), is from 31.9 to 103.9 mg/g. By varying the synthesis conditions, it was shown that the greatest sorption capacity with respect to MB is achieved at the time of hydrolysis of the original rice straw for 60 minutes. It is shown that the sorption of Cs+ ions in the obtained samples is described by the Langmuir model. The sorption properties with respect to Cs+ ions from aqueous solutions with different salt background were studied.
Fe
x
(O, OH)
y
–SiO
2
composite samples are prepared. The composite matrix is amorphous silica prepared by controlled precipitation from silicate solutions or silica derived from rice husks. The iron ...is shown to exist in the form of acagenite β-FeO(OH) or hematite α-Fe
2
O
3
. The magnetic properties of the composites are studied at temperatures in the range 2–300 K and fields in the range ±5 T. The composite samples exhibit superparamagnetic properties.
The concept of the TAIGA experiment is to combine wide-angle timing and imaging Cherenkov telescopes as well as electron and muon detectors. The TAIGA facility aims at gamma-ray astrophysics at ...energies from a few TeV to several PeV and cosmic-ray physics from 100 TeV to several EeV but also pursues searches for astrophysical nanosecond transients, axion-like particles, Lorentz invariance violation and other unexpected manifestations of New Physics. TAIGA-1, a hybrid detector complex with an area of 1 km2, operating since 2021 in the Tunka valley, 50 km to the West from the southernmost tip of lake Baikal, and the plans for its upgrade are presented.
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