ABSTRACT We present a comprehensive study of the excitation of C i fine-structure levels along 57 sight lines in the Large and Small Magellanic Clouds (LMC and SMC). The sightlines were selected by the detection of H2 in FUSE spectra. Using archival HST/COS and HST/STIS spectra, we detected absorption of C i fine-structure levels and measured their populations for 29 and 28 sightlines in the LMC and SMC, respectively. The C i column density ranges from 1013 to $10^{14}\, {\rm cm}^{-2}$ for the LMC and 1013 to $10^{15.4}\, {\rm cm}^{-2}$ for the SMC. We found excitation of C i fine-structure levels in the LMC and SMC to be 2–3 times higher than typical values in local diffuse interstellar medium (ISM). Comparing excitation of both C i fine-structure levels and H2 rotational levels with a grid of PDR Meudon models, we find that neutral cold gas in the LMC and SMC is illuminated by a stronger UV field than in local ISM ($\chi =5^{+7}_{-3}$ units of Mathis field for the LMC and $2^{+4}_{-1}$ for the SMC) and has on average higher thermal pressure (log p/k = 4.2 ± 0.4 and 4.3 ± 0.5, respectively). Magellanic Clouds sight lines likely probe regions near star-formation sites, which also affects the thermal state and C i/H2 relative abundances. At the same time, obtained enhanced UV field is consistent with some measurements at high redshifts. Together with low metallicities, this make Magellanic Clouds an interesting test case to study the central parts of high redshift galaxies.

Simultaneous measurements of the brightness temperature and short-period electric field fluctuations were carried out to reveal possible connections between the electrification rate and turbulence intensity in clouds. The measurements were conducted in Nizhny Novgorod, Russia (56 degrees 19'37 '' N 44 degrees 00'27 '' E) in 2013 and 2018. The 8 mm radiometer was used to measure the brightness temperature of thermal radiation, and the vertical component of the atmospheric electric field were carried out using an electrostatic fluxmeter. With the use of meteorological data and electric field measurements the state of analyzed events has been classified into 4 types: cloudless atmosphere and high-level clouds (Cs), cumulus clouds (Cu), cumulonimbus clouds without lightning that cause strong electrical field disturbances near the ground surface (Cb), cumulonimbus thunderstorm clouds with lightning discharges (Cb+). Detailed statistical characteristics of brightness temperature fluctuations and short-period electric field fluctuations are obtained for the first time for the indicated types of events. It is shown that measured spectral densities of the atmosphere brightness temperature and electric field fluctuations correspond well enough in the considered frequency range to the results of presented theoretical consideration. Precipitation particles in clouds can be considered herewith as passive scalar, and the movement of inhomogeneities in the particle density can be described by Kolmogorov theory. Since electric charges are located on the precipitation with small droplet and ice particles, an increase in the inhomogeneities of the water content means likely an increase in the inhomogeneities of the electric charge. For thunderclouds the estimates of the relative fluctuations of liquid water content give values of the order of tens of percent. There is a tendency towards a relative increase in brightness temperature fluctuations at high frequencies in the band around f approximate to 10(-2) Hz (and possibly higher than f(max) approximate to 0.05 Hz) for the sequence of cloud types Cu, Cb, Cb+.

ABSTRACTThe precision measurement of the primordial helium abundance Yp is a powerful probe of the early Universe. The most common way to determine Yp is the analyses of observations of metal-poor H ii regions found in blue compact dwarf galaxies. We present the spectroscopic sample of 100 H ii regions collected from the Sloan Digital Sky Survey. The final analysed sample consists of our sample and HeBCD data base from Izotov et al. (2007). We use a self-consistent procedure to determine physical conditions, current helium abundances, and metallicities of the H ii regions. From a regression to zero metallicity, we have obtained Yp = 0.2462 ± 0.0022, which is one of the most stringent constraints obtained with such methods up to date and is in a good agreement with the Planck result $Y_{\rm p}^{\it {\mathrm{ Planck}}} = 0.2471 \pm 0.0003$. Using the determined value of Yp and the primordial deuterium abundance taken from Particle Data Group (Zyla et al. 2020) we put a constraint on the effective number of neutrino species Neff = 2.95 ± 0.16, which is consistent with the Planck one Neff = 2.99 ± 0.17. Further increase of statistics potentially allows us to achieve Planck accuracy, which in turn will become a powerful tool for studying the self-consistency of the standard cosmological model and/or physics beyond.

The linear increase of the cosmic microwave background (CMB) temperature with cosmological redshift, $$T_{\textrm{CMB}}=T_{{0}}(1+z)$$ , is a prediction of the standard cosmological $$\Lambda$$ CDM model. There are currently two methods to measure this dependence at redshift $$z>0$$ and, what is equally important, to estimate of the CMB temperature $$T_{0}$$ at the present epoch. The first method is based on the Sunyaev–Zeldovich effect for a galaxy cluster. However, this method is limited to redshifts $$z\lesssim 1$$ and only the deviations from the standard relation can be measured with it. The second method is based on the analysis of the populations of atomic and molecular energy levels observed in the absorption spectra of quasars. This method allows $$T_{\textrm{CMB}}(z)$$ to be measured directly. We present new estimates of $$T_{\textrm{CMB}}(z_{i})$$ in the redshift range $$1.7\leq z_{i}\leq 3.3$$ based on the analysis of the excitation of CO rotational levels and C I fine-structure levels in 15 absorption systems. We take into account the collisional excitation of CO and C I with hydrogen atoms and $$\textrm{H}_{2}$$ and the radiative pumping of C I by the interstellar ultraviolet radiation. Applying this corrections leads to a systematic decrease in the previously obtained estimates of $$T_{\textrm{CMB}}(z_{i})$$ (for some systems the magnitude of the effect is $${\sim}10\%$$ ). Combining our measurements with the measurements of $$T_{\textrm{CMB}}(z)$$ in galaxy clusters we have obtained a constraint on the parameter $$\beta=+0.010\pm 0.013$$ , which characterizes the deviation of the CMB temperature from the standard relation, $$T_{\textrm{CMB}}=T_{{0}}(1+z)^{1-\beta}$$ , and an independent estimate of the CMB temperature at the present epoch, $$T_{0}=2.719\pm 0.009$$ K, which agrees well with the estimate from orbital measurements, $$T_{0}=2.7255\pm 0.0006$$ K.

We have performed a theoretical calculation of the influence of radiative pumping on the populations of the rotational levels of the ground vibrational state for HD molecules under conditions of the cold phase of the interstellar medium. Two main excitation mechanisms have been taken into account in our analysis: (i) collisions with atoms and molecules of the interstellar medium and (ii) radiative pumping by the ultraviolet interstellar background. The radiative pumping rate coefficients $$\Gamma_{ij}$$ corresponding to the average galactic ultraviolet background in Draine’s model have been determined. The influence of HD self-shielding on the radiative pumping rate coefficients has been studied. The population of the first HD rotational level ( $$J=1$$ ) is shown to be determined mainly by radiative pumping rather than by collisions if the thermal gas pressure $$p_{\rm th}\leq 10^{4}\left(\frac{I_{\textrm{UV}}}{1}\right)\textrm{ K cm}^{-3}$$ and the column density $$\log N({\textrm{HD}})<15$$ . In such clouds the relative population of the HD levels $$N(J=1)/N(J=0)$$ turns out to be more sensitive to the ultraviolet background intensity than the relative population of the C I fine-structure levels. Thus, an analysis of the relative HD level population can become an important additional source of information about the physical conditions in the interstellar medium both in our Galaxy and in the forming galaxies of the early Universe.

ABSTRACT We have searched high spectral resolution spectra of quasars known to exhibit high redshift (z > 1.7) intervening H2-bearing damped Lyman-α (DLA) systems for partial coverage of the quasar emission by intervening H2 clouds. Partial coverage manifests itself by the presence of non-zero residual flux in the core of saturated H2 absorption lines. The residual flux can be observed either only at the bottom of absorption lines redshifted on top of quasar emission lines, in which case part of the broad line region (BLR) is not covered, or in all absorption lines, in case some continuum source is not covered. Among 35 H2 absorption clouds in 14 quasar spectra obtained with the VLT-UVES or Keck-HIRES spectrographs, we detect partial coverage of the BLR for 13 clouds. This result suggests that the probability of partial coverage of the QSO BLR by a distant H2 absorption cloud is about 40 per cent. For four systems towards Q 0013−0029, Q 0405−4418, Q 0812+3208, and J 2100−0641, partial coverage is detected for the first time. We determine the theoretical probability of partial coverage of the BLR by a distant H2 cloud as a function of the ratio between the cloud and the BLR sizes. Using this model, we obtain an estimate of the characteristic BLR radius of $50^{+19}_{-23}\,\rm{light \,days}$. This is similar to the estimate of the BLR size obtained by reverberation-mapping analysis $({\sim}100\,\rm{light\, days})$.

Experimental and theoretical investigations of atmospheric electric field fluctuations in the wide range of time periods are being of interest for atmospheric turbulence diagnostics and global source signal recognition [1]. The present paper is devoted to investigation of short time electric field fluctuations in the lower atmosphere and their correlations with other troposphere parameters. Simultaneous measurements of fluctuations in the surface atmospheric electric field and brightness temperature were carried out in Nizhny Novgorod in 2013-2014 and 2018-2020. The electric-field sensors, i.e.., electrostatic fluxmeters, and two microwave radiometers with a wavelength of 8 mm and 3 sm were located in Nizhny Novgorod City on the roof of the Institute of Applied Physics of the Russian Academy of Sciences (IAP RAS) [56°19’25’’ N 44°01’21’’ E].

ABSTRACT We present the results of an analysis of the physical conditions (number density, intensity of UV field, kinetic temperature) in the cold H2-bearing interstellar medium of local and high-redshift galaxies. Our measurements are based on the fit to the observed population of H2 rotational levels and C i fine-structure levels with the help of grids of numerical models calculated with the photon-dominated region (PDR) Meudon code. A joint analysis of low H2 rotational levels and C i fine-structure levels breaks the degeneracy in the IUV−nH plane and provides significantly tighter constraints on the number density and intensity of the UV field. Using archive data from the VLT/UVES, KECK/HIRES, HST/STIS and FUSE telescopes, we selected 12 high-redshift damped Lyα systems (DLAs) in quasar spectra and 14 H2 absorption systems along the lines of sight towards stars in the Milky Way and the Magellanic Cloud galaxies. These systems have strong H2 components, with a column density log N(H2)/[cm−2] > 18 and associated C i absorptions. We find that H2-bearing media in high-redshift DLAs and in local galaxies have similar values of the kinetic temperatures Tkin ∼ 100 K and number density 10−500 cm−3. However, the intensity of incident UV radiation in DLAs varies in a wide range (0.1−100 units of the Mathis field), while it is ∼0.1−3 units of the Mathis field for H2 systems in the Milky Way and Large and Small Magellanic Cloud galaxies. The large dispersion of measured UV flux in DLAs is probably a consequence of the fact that the DLA sample probes galaxies selected from the overall galaxy population at high redshift, and therefore corresponds to a wide range of physical conditions.

Cognitive assistants are the promising and intensively growing field nowadays. Some of them provide powerful mechanisms of monitoring and control of individual's health, and mental health, in particular. Yet, some aspects of mental health and individual's safety are still uncovered: the problem has not been considered in terms of Social Media effect on the individual's life and self-estimation level. In the current paper the problem of individual's safety in the Internet is proposed to be solved with the cognitive assistant, based on the authorship identification techniques. The search of fake accounts is a time-consuming procedure, so it is highly desirable to decrease the time of data processing. Taking into account the peculiarities of the fog-computing concept, the technique of data analysis tasks distribution is proposed. It is based on the appropriate location of the search agents nearby the data source, where the information stores.

A problem of the electric field dynamics in turbulent electro-active clouds (Cumulus, Stratus, Cumulonimbus) is one of the most relevant and complex problems of dynamical meteorology and atmospheric electricity. This problem is important for the study of intense large-scale electric field and its fluctuations that may lead to high-energy particle flows and lightning discharges, for electric current parameterization. Direct field measurements in convective clouds with a developed electrical structure are very difficult; so one of urgent tasks is the development of remote sensing methods for turbulence characteristics in electro-active clouds. The growth of a large-scale electric field in a turbulent atmosphere is caused by the generation of an electric charge on colliding particles (hydrometeors and dust). Meanwhile, observations (including preliminary observations of the authors) and theoretical studies (Mareev and Dementyeva, 2017) show that intensification of thunderstorm activity can be associated with increased turbulence in the cloud. This paper presents new ideas and results of experimental and theoretical studies of the role of turbulence in electro-active clouds. The main attention is paid to complex remote observations of different types of clouds with an experimental set-up including the microwave radiometers of 3 cm and 8 mm wavelengths (with a time resolution of order of one second), the network of electrostatic fluxmeters spaced by several kilometers each from another, and the meteorological radar. The data of recent several years were used for analysis. Note that recently space-borne passive microwave radiometry of intense convective clouds (see, for example, Peterson et al., 2017) attracted more attention compared to ground-based microwave observations. A principal idea of our approach is to use the wave-length channels allowing us to reveal both optically thick and optically transparent cloud events from the data on fluctuations in the brightness temperature of the atmosphere. A special attention was paid to comparative analysis of the turbulence characteristics in thunderclouds and in clouds that do not have a developed electrical structure. The spectral characteristics of electric field and brightness fluctuations were found to be associated with atmospheric air turbulence and mostly are quantitatively described by Kolmogorov-type spectra. Compared with ordinary Cumulus and Stratus clouds, a limited band near a frequency of ~ 0.01 Hz with a higher level of fluctuations is distinguished in the spectral density of fluctuations in the brightness temperature of thunderclouds. The spectra of fluctuations of the electric field caused by thunderclouds, as well as turbulence interior thundercloud, are significantly different from the spectra caused by ordinary Cumulus and layered clouds. The work was supported by the Russian Foundation for Basic Research (projects no. 19-05-00975 and 18-45-520010). References Mareev E.A., Dementyeva S.O. (2017), The role of turbulence in thunderstorm, snowstorm, and dust storm electrification. Journal of Geophysical Research: Atmospheres, V. 122, No. 13, P. 6976-6988. doi: 10.1002/2016JD026150. Peterson M., Liu C., Mach D., Deierling W., Kalb C. (2015), A method of estimating electric fields above electrifi_ed clouds from passive microwave observations. J. Atmos. Ocean. Tech., V.32 (8), P.1429-1446. doi: 10.1175/ JTECH-D-14-00119.1.

ABSTRACT We present results from spectroscopic observations with X-shooter at the Very Large Telescope of seven H2-bearing damped Lyman-α systems (DLAs) at high redshifts (zabs ∼ 2.5–3). These DLAs were originally selected from the presence of strong H2 lines directly seen at the DLA redshift in low-resolution low signal-to-noise ratio SDSS spectra. We confirm the detection of molecular hydrogen in all of them. We measure the column densities of H i, H2 in various rotational levels, and metal species, and associated dust extinction. The metallicities, obtained from undepleted species, are in the range log Z = −0.8 to −0.2. We discuss the chemical enrichment in these clouds and compare their properties with that of other molecular-rich systems selected by other means. In particular, we show that three different methods of pre-selection of H2-bearing DLAs in the SDSS have their own biases but complement each other mostly in terms of chemical enrichment. We use the rotational excitation of H2 molecules together with the fine-structure energy levels of neutral carbon to constrain the physical conditions in the gas with the help of numerical modelling as well as analytical expressions for the surface density at which atomic to molecular conversion happens. We find that the H2-bearing medium revealed by the studied DLAs has typical values for the kinetic temperature, hydrogen density, and UV radiation field of T ∼ 100 K, nH ∼ 100 cm−3, and IUV , respectively, about twice the intensity of the Draine field. Detailed studies combining different selections should therefore bring important clues to understand the H i-H2 transition at high redshift.

We present spectroscopic data on metal-deficient HII regions from dwarf galaxies of the Local Volume on the basis of Sloan Digital Sky Survey (SDSS) Data Release 15 observations. Using the data on the intensities of the optical emission lines of the HII regions, one can determine their chemical composition, as well as other physical properties, such as temperature and electron density. Oxygen abundance (and thus the metallicity) of the source is determined using direct method by using strong [OIII] lines. Here we present only sources with oxygen abundance below 12 + logO/H = 8.5. These data is used to determine primordial helium abundance, which value should be determined with as little errors as possibles. The main way to reduce errors is to use the spectroscopic data of the highest quality possible. On the other hand one can statistically decrease evaluation errors by using large dataset. Main focus of this paper is studying if we can decrease errors in Y-p determination by combining HeBCD sample with SDSS spectra of lower quallity.

We present the results of spectroscopic analysis of seven new H 2 -bearing damped Ly- systems in redshift range z=2.5 − 3. These systems were originally selected from SDSS catalog using a direct search for H 2 and followed up with X-SHOOTER spectrograph at 8-m Very Large Telescope observatory. We measured the column densities of H I , H 2 on various rotational levels, and metals species in different ionization stages and excitation levels. We used the rotational excitation of H 2 molecules together with the fine-structure levels of neutral carbon to constrain the physical conditions in the associated medium. We found typical values for the kinetic temperature T ∼ 80 − 120 K, hydrogen density n H ∼ 30 − 400 cm −3 and UV radiation field ξ UV ∼ 0.4 − 5 times of the Draine field. These values along with estimated thermal pressure are in agreement with expected values from the theoretical calculation of the cold neutral interstellar medium.

We describe the method and the results of modeling and retrieval of the spatial distribution of excited oxygen atoms in the HF-pumped ionospheric region based on two-station records of artificial airglow in the red line (λ = 630 nm). The HF ionospheric pumping was provided by the Sura facility. The red-line records of the night-sky portraits were obtained at two reception points—directly at the heating facility and 170 km east of it. The results were compared with the vertical ionospheric sounding data. It was found that in the course of the experiments the airglow region was about 250 km high and did not depend on the altitude of the pump-wave resonance. The characteristic size of the region was 35 km, and the shape of the distribution isosurfaces was well described by oblique spheroids or a drop-shaped form. The average value of the maximum concentration of excited atoms during the experiment was about 1000 cm −3 .

The influence of disturbed weather regions on electric processes in the atmosphere is of considerable interest in the global electric circuit (GEC) investigations. Recent studies [1]–[2] show that the contribution of clouds into the global electric circuit still requires careful research to refine existing models. Among the conductivity inhomogeneities typical for various elements of the GEC the perturbed regions associated with thunderstorm and non-thunderstorm clouds occupy an important place [3]. The conductivity of the Stratus and Cumulus clouds can be significantly reduced in comparison with the fair-weather conductivity of the ambient air. Such heterogeneities can significantly affect the structure and quantitative characteristics of the GEC.

We present a detailed analysis of an H-2-rich, extremely strong intervening damped Ly alpha absorption system (DLA) at z(abs) = 2.786 towards the quasar J 0843+ 0221, observed with the Ultraviolet and Visual Echelle Spectrograph on the Very Large Telescope. The total column density of molecular (resp. atomic) hydrogen is log N(H-2) = 21.21 +/- 0.02 (resp. log N(H I) = 21.82 +/- 0.11), making it to be the first case in quasar absorption line studies with H2 column density as high as what is seen in (CO)-C-13-selected clouds in the Milky Way. We find that this system has one of the lowest metallicity detected among H-2-bearing DLAs, with [Zn/H] = -1.52(-0.10)(+0.08). This can be the reason for the marked differences compared to systems with similar H-2 column densities in the local Universe: (i) the kinetic temperature, T similar to 120 K, derived from the J = 0, 1 H-2 rotational levels is at least twice higher than expected; (ii) there is little dust extinction with A(V) < 0.1; (iii) no CO molecules are detected, putting a constraint on the X-CO factor X-CO > 2 x 10(23) cm(-2)/(km s(-1) K), in the very low metallicity gas. Low CO and high H-2 contents indicate that this system represents 'CO-dark/faint' gas. We investigate the physical conditions in the H-2-bearing gas using the fine-structure levels of C I, CII, Si II and the rotational levels of HD and H-2. We find the number density to be about n similar to 260-380 cm(-3), implying a high thermal pressure of 3-5 x 10(4) cm(-3) K. We further identify a trend of increasing pressure with increasing total hydrogen column density. This independently supports the suggestion that extremely strong DLAs (with log N(H)similar to 22) probe high-z galaxies at low impact parameters.

This paper presents the calculations of synchrotron radio emission intensity from Van Allen belts with Gaussian space distribution of electron density across L-shells of a dipole magnetic field, and with Maxwell’s relativistic electron energy distribution. The results of these calculations come to a good agreement with measurements of the synchrotron emission intensity of the artificial radiation belt’s electrons during the Starfish nuclear test. We have obtained two-dimensional distributions of radio brightness in azimuth — zenith angle coordinates for an observer on Earth’s surface. The westside and eastside intensity maxima exceed several times the maximum level of emission in the meridian plane. We have also constructed two-dimensional distributions of the radio emission intensity in decibels related to the background galactic radio noise level. Isotropic fluxes of relativistic electrons (E ~ 1 MeV) should be more than 107 cm–2s–1 for the synchrotron emission intensity in the meridian plane to exceed the cosmic noise level by 0.1 dB (riometer sensitivity threshold).