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The interrelation between the concepts of self-consistency, relativism and many-particle systems is considered within the framework of a unified consideration of classical and quantum physics based on the first principle of the probability conservation law. The probability conservation law underlies the Vlasov equation chain. From the first Vlasov equation, the Schr\"odinger equation, the Hamilton-Jacobi equation, the equation of motion of a charged particle in an electromagnetic field, the Maxwell equations, the Pauli equation and the Dirac equation are constructed. The paper shows with mathematical rigor that quantum systems with a time independent function of quasi-density probability in phase space are not capable to emit electromagnetic radiation. It is shown that at the micro-level a quantum object may be considered rather as an {\guillemotleft}extended{\guillemotright} object than a point one. And the hydrodynamic description of continuum mechanics is applicable for such an object. A number of exact solutions of quantum and classical model systems is considered, demonstrating a new insight at the quantum mechanics representation., Comment: 44 pages, 4 figures

The paper considers the mathematical formulation of the problem of transverse oscillations of a vertical rod under gravity, friction and external pulse effect, leading to thermal expansion of the rod. The dynamics of the system under consideration corresponds to the behavior of a fuel element (FE) in a pulsed reactor and is related to the dynamic stability of the processes occurring in it. The FE dynamics is described by inhomogeneous linear differential equation of the fourth order with non-constant coefficients. Initial boundary conditions are not smooth since they correspond to the instant heating of the part of the FE surface exposed to neutron pulse radiation. In the future the obtained exact solutions will be used as input data to simulate self-consistent system dynamics of more than 50 FE., Comment: 41 pages, 23 figures

We present a comprehensive study of the excitation of CI fine-structure levels along 57 sight lines in the Large and Small Magellanic Clouds. The sight lines were selected by the detection of H$_2$ in FUSE spectra. Using archival HST/COS and HST/STIS spectra we detected absorption of CI fine-structure levels and measured their populations for 29 and 22 sight lines in the LMC and SMC, respectively. The CI column density ranges from $10^{13}$ to $10^{14}\,{\rm cm}^{-2}$ for the LMC and $10^{13}$ to $10^{15.4}\,{\rm cm}^{-2}$ for the SMC. We found excitation of CI fine-structure levels in the LMC and SMC to be 2-3 times higher than typical values in local diffuse ISM. Comparing excitation of both CI fine-structure levels and H$_2$ rotational levels with a grid of PDR Meudon models we find that neutral cold gas in the LMC and SMC is illuminated by 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 ($\log p/k =4.2\pm0.4$ and $4.3\pm0.5$, respectively). Magellanic Clouds sight lines likely probe region near star-formation sites, which also affects the thermal state and CI/H$_2$ relative abundances. At the same time such high measurements of UV field are consistent with some values obtained at high redshifts. Together with low metallicities this make Magellanic Clouds to be an interesting test case to study of the central parts of high redshift galaxies., Comment: submitted to MNRAS

We analyze the cool gas in and around 14 nearby galaxies (at $z$$<$0.1) mapped with the SDSS-IV MaNGA survey by measuring absorption lines produced by gas in spectra of background quasars/AGN at impact parameters of 0-25 effective radii from the galaxy center. Using HST/COS, we detect absorption at the galaxy redshift and measure or constrain column densities of neutral (H I, N I, O I, Ar I), low-ionization (Si II, S II, C II, N II Fe II), and high-ionization (Si III, Fe III, N V, O VI) species for 11 galaxies. We derive the ionization parameter and ionization-corrected metallicity using CLOUDY photo-ionization models. The H I column density ranges from $\sim$$10^{13}$ to $\sim$$10^{20}\,{\rm cm^{-2}}$ and decreases with impact parameter for $r \ge R_{e}$. Galaxies with higher stellar mass have weaker H I absorption. Comparing absorption velocities with MaNGA radial velocity maps of ionized gas line emissions in galactic disks, we find that the neutral gas seen in absorption co-rotates with the disk out to $\sim$10 $R_{e}$. Sight lines with lower elevation angles show lower metallicities, consistent with the metallicity gradient in the disk derived from MaNGA maps. Higher elevation angle sight lines show higher ionization, lower H I-column density, super-solar metallicity, and velocities consistent with the direction of galactic outflow. Our data offer the first detailed comparisons of CGM properties (kinematics and metallicity) with extrapolations of detailed galaxy maps from integral field spectroscopy; similar studies for larger samples are needed to more fully understand how galaxies interact with their CGM., Comment: Accepted for publication in ApJ, 49 pages, 36 figures

Pulsars with periods more than 0.4 seconds in the declination range -9o < decj < 42o and in the right ascension range 0h < r.a.< 24h were searched in parallel with the program of interplanetary scintillations monitoring of a large number of sources with the radiotelescope LPA LPI. Four-year observations carried out at the central frequency 110.25 MHz in the band 2.5 MHz and in six frequency channels with the time resolution 100 ms were used for the search. Initial detections of candidates for pulsars were based on the Fourier power spectra averaged over the whole observations period. The candidates for pulsars were checked in more details from observations analysis with higher time-frequency resolution: 32 frequency channels with time resolution of 12.5 ms. 18 new pulsars was discovered, their main characteristics are presented., Comment: published in Astronomy Report, translated by Yandex translator with correction of scientific lexis, 9 pages, 5 figures, 1 table

The linear increase of the cosmic microwave background (CMB) temperature with cosmological redshift, $T_{\rm CMB} = T_0(1 + z)$, is a prediction of the standard cosmological $\Lambda$CDM model. There are currently two methods to measure this dependence at redshift $z>0$, and that is equally important to estimate the CMB temperature $T_0$ at the present epoch $z=0$. The first method is based on the Sunyaev-Zeldovich (SZ) effect for a galaxy cluster. aThe 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 $T_{\rm CMB}(z)$ to be measured directly. We present new estimates of $T_{\rm CMB}(z_i)$ in the redshift range $1.7\le z_i \le3.3$ based on the analysis of excitation of the CO rotational levels and C\,{\sc i} fine-structure levels in 15 absorption systems. We take into account collisional excitation of CO and C\,{\sc i} with hydrogen atoms and H$_2$ and radiative pumping of C\,{\sc i} by the interstellar ultraviolet radiation. Applying this corrections leads to a systematic decrease in the previously obtained estimates of $T_{\rm CMB}(z_i)$ (for some systems the magnitude of the effect is $\sim$10\%). Combining our measurements with the measurements of $T_{\rm CMB}(z)$ in galaxy clusters we have obtained a constraint on the parameter $\beta=+0.010\pm0.013$, which characterizes the deviation of the CMB temperature from the standard relation, $T_{\rm CMB} = T_0(1 + z)^{1-\beta}$, and an independent estimate of the CMB temperature at the present epoch, $T_0 = 2.719\pm0.009$\,K, which agrees well with the estimate from orbital measurements, $T_0 = 2.7255\pm0.0006$\,K. This independent estimate is very important because it was obtained using cosmological data, in contrast to satellite measurements, which are obtained "here" and "now"., Comment: 8 pages, 4 figures, 5 tables

We present a theoretical calculation of the influence of ultraviolet radiative pumping on the excitation of the rotational levels of the ground vibrational state for HD molecules under conditions of the cold diffuse interstellar medium (ISM). Two main excitation mechanisms have been taken into account in our analysis: (i) collisions with atoms and molecules and (ii) radiative pumping by the interstellar ultraviolet (UV) radiation field. The calculation of the radiative pumping rate coefficients $\Gamma_{\rm ij}$ corresponding to Drane's model of the field of interstellar UV radiation, taking into account the self-shielding of HD molecules, is performed. We found that the population of the first HD rotational level ($J = 1$) is determined mainly by radiative pumping rather than by collisions if the thermal gas pressure $p_{\rm th}\le10^4\left(\frac{I_{\rm{UV}}}{1}\right)\,\mbox{K\,cm}^{-3}$ and the column density of HD is lower than $\log N({\rm{HD}})<15$. Under this constraint the populations of rotational levels of HD turns out to be as well a more sensitive indicator of the UV radiation intensity than the fine-structure levels of atomic carbon. We suggest that taking into account radiative pumping of HD rotational levels may be important for the problem of the cooling of primordial gas at high redshift: ultraviolet radiation from first stars can increase the rate of HD cooling of the primordial gas in the early Universe., Comment: 9 pages, 5 figures, 3 tables

The precision measurement of the primordial helium abundance $Y_p$ is a powerful probe of the early Universe. The most common way to determine $Y_p$ is analyses of observations of metal-poor \HII regions found in blue compact dwarf galaxies. We present the spectroscopic sample of 100 \HII regions collected from the Sloan Digital Sky Survey. The final analysed sample consists of our sample and HeBCD database from Izotov et al. 2007. We use a self-consistent procedure to determine physical conditions, current helium abundances, and metallicities of the \HII regions. From a regression to zero metallicity, we have obtained $Y_p = 0.2462 \pm 0.0022$ 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 $Y_{\rm p}^{\it {Planck}} = 0.2471 \pm 0.0003$. Using the determined value of $Y_p$ 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 $N_{\rm eff} = 2.95 \pm 0.16$ which is consistent with the Planck one $N_{\rm eff} = 2.99 \pm 0.17$. 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., Comment: 12 pages, 5 figures

We present results of analysis of physical conditions (number density, intensity of UV field, kinetic temperature) in the cold H$_2$-bearing interstellar medium of local and high redshift galaxies. Our measurements based on the fit to the observed population of H$_2$ rotational levels and CI fine-structure levels with the help of grids of numerical models calculated with the PDR Meudon code. A joint analysis of low H$_2$ rotational levels and CI fine-structure levels allows to break the degeneracy in the $I_{UV}-n_{\rm{H}}$ plane and provides significantly tighter constraints on the number density and intensity of UV field. Using archive data from the VLT/UVES, KECK/HIRES, HST/STIS and FUSE telescopes we selected 12 high redshift damped Ly$\alpha$ systems (DLAs) in quasar spectra and 14 H$_2$ absorption systems along the lines of sight towards stars in the Milky-Way and the Magellanic Clouds galaxies. These systems have strong H$_2$ components with the column density $\log N({\rm{H_2}})/{\rm{cm}}^{-2}>18$ and associated CI absorptions. We find that H$_2$-bearing medium in high redshift DLAs and in local galaxies has similar values of the kinetic temperatures $T_{\rm{kin}}\sim100$K and number density $10-500$ cm$^{-3}$. However, the intensity of incident UV radiation in DLAs is varied in the wide range ($0.1-100$ units of Mathis field), while it is $\sim0.1-3$ units of Mathis field for H$_2$ systems in Milky-Way and LMC and SMC galaxies. The large dispersion of measured UV flux in DLAs is probably a consequence that DLA sample probes the galaxies selected from the overall galaxy population at high-z and therefore corresponds to the wide range of the physical conditions., Comment: 20 pages, 14 figures, accepted for publication in MNRAS

We present results from spectroscopic observations with X-shooter at the Very Large Telescope of seven H2-bearing DLAs at high redshifts (z$_{\rm abs}\sim 2.5-3$). These DLAs were originally selected from the presence of strong H$_2$ lines directly seen at the DLA redshift in low-resolution, low S/N SDSS spectra. We confirm the detection of molecular hydrogen in all of them. We measure the column densities of HI, H$_2$ in various rotational levels, and metal species, and associated dust extinction. The metallicities, obtained from undepleted species, are in the range logZ=-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 H$_2$-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 H$_2$ molecules together with the fine-structure energy levels of neutral carbon to constrain the physical conditions in the gas with the help of numerical modeling as well as analytical expressions for the surface density at which atomic to molecular conversion happens. We find that the H$_2$-bearing medium revealed by the studied DLAs has typical values for the kinetic temperature, hydrogen density, and UV radiation field of, respectively, T$\sim$100K, $n_{\rm H}\sim 100$ cm$^{-3}$, and I$_{\rm UV}$ about twice the intensity of the Draine field. Detailed studies combining different selections should, therefore, bring important clues to understand the HI-H$_2$ transition at high redshift., Comment: 42 pages, 50 figures, accepted for publication in MNRAS

The All-sky Medium Energy Gamma-ray Observatory (AMEGO) is a probe class mission concept that will provide essential contributions to multimessenger astrophysics in the late 2020s and beyond. AMEGO combines high sensitivity in the 200 keV to 10 GeV energy range with a wide field of view, good spectral resolution, and polarization sensitivity. Therefore, AMEGO is key in the study of multimessenger astrophysical objects that have unique signatures in the gamma-ray regime, such as neutron star mergers, supernovae, and flaring active galactic nuclei. The order-of-magnitude improvement compared to previous MeV missions also enables discoveries of a wide range of phenomena whose energy output peaks in the relatively unexplored medium-energy gamma-ray band., Comment: Astro2020 APC White Paper Updated to make small change to author list in metadata

We present a detailed analysis of a H$_2$-rich, extremely strong intervening Damped Ly-$\alpha$ Absorption system (DLA) at $z_{\rm abs}=2.786$ 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$_2$)=$21.21\pm0.02$ (resp. $\log N$(H$\,$I)=$21.82\pm0.11$), making it to be the first case in quasar absorption lines studies with H$_2$ column density as high as what is seen in $^{13}$CO-selected clouds in the Milky-Way. We find that this system has one of the lowest metallicity detected among H$_2$-bearing DLAs, with $\rm [Zn/H]=-1.52^{+0.08}_{-0.10}$. 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\sim$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 $X_{\rm CO}$ factor $X_{\rm CO}> 2\times 10^{23} $ cm$^{-2}$/(km/s\,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, C$\,$II, Si$\,$II and the rotational levels of HD and H$_2$. We find the number density to be about $n \sim 260-380\,$cm$^{-3}$, implying a high thermal pressure of $(3-5) \times 10^4\,$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) $\sim 22$) probe high-z galaxies at low impact parameters., Comment: 21 pages, 21 figures. Accepted for publication in MNRAS