The dynamics of expansion and large-scale structure formation the Universe are analyzed for models with dark energy in form a phantom scalar field which initially mimics $\ensuremath{\Lambda}$-term evolves slowly to Big Rip singularity. discussed model has three parameters---the density equation state parameter at current epoch, ${\ensuremath{\Omega}}_{\mathrm{de}}$ ${w}_{0}$, asymptotic value $a\ensuremath{\rightarrow}\ensuremath{\infty}$, ${c}_{a}^{2}$. Their best-fit values determined...

We estimate the global signal in redshifted hyperfine structure line 21 cm of hydrogen atoms formed during dark ages and cosmic dawn epochs. The evolution brightness temperature this was computed to study its dependence on physical conditions intergalactic medium. show that profile crucially depends ionization baryonic matter, as well spectral energy distribution radiation from first sources. cosmological models with self-annihilating decaying matter allowable parameters by current...

The formation of the first stars and galaxies at Cosmic Dawn was preceded by primordial chemistry reactions during Dark Ages, generating molecules, H_2, HD, HeH^+, which were critical for emergence stars. These molecules absorb scatter cosmic microwave background (CMB) quanta leading to distortion CMB spectrum. We aimed estimate how much bound-bound transitions between rovibrational levels HeH^+ contribute spectrum in standard ΛCDM cosmology. modelled kinetics using a system 166 chemical...

ABSTRACT We analyse the formation of redshifted hyperfine structure line 21-cm hydrogen atom in Dark Ages, Cosmic Dawn, and Reionization epochs. The evolution global differential brightness temperature this was computed to study its dependence on values cosmological parameters physical conditions intergalactic medium. Variations depth Ages absorption at z ∼ 80 with variations Ωb, Ωcdm, ΩΛ, ΩK, H0 are studied. standard model post-Planck predicts a value centre ∼30–50 mK. profile can be quite...

The possibility of reconstruction Lagrangian for the scalar field dark energy with constant effective sound speed $c_s$ is analyzed. It found that such can be made accuracy up to an arbitrary constant. value estimated together other parameters ($\Omega_{de}$, $w_0$, $c_a^2$) and main cosmological ones on basis data including Planck-2013 results CMB anisotropy, BAO distance ratios from recent galaxy surveys, power spectrum WiggleZ, magnitude-redshift relations distant SNe Ia SNLS3 Union2.1...

We analyze the formation of signal in 21 cm hydrogen line Dark Ages (30 ≤ z 300) different cosmological models and discuss possibility its detection by decameter-wavelength radio telescopes.To study dependence intensity profile on values parameters physical conditions intergalactic medium, evolution global (averaged over sky) differential brightness temperature this was calculated standard non-standard with parameters.The ΛCDM model predicts a value center absorption δT br ≈ -35 mK at 87.The...

We analyze the possibility to distinguish between quintessence and phantom scalar field models of dark energy using observations luminosity distance moduli SNe Ia, CMB anisotropies polarization, matter density perturbations baryon acoustic oscillations. Among present only Planck data on anisotropy SDSS DR9 oscillations may be able decide or models, however for each model a set best-fit parameters exists, which matches all with similar goodness fit. compare relative differences predictions...

The book elucidates the current state of dark energy problem and presents results authors, who work in this area. It describes observational evidence for existence energy, methods constraining its parameters, modeling by scalar fields, space-times with extra spatial dimensions, especially Kaluza---Klein models, braneworld models a single dimension as well problems positive definition gravitational General Relativity, conditions consequences their violation presence energy. This monograph is...

The locations and amplitudes of three acoustic peaks two dips in the last releases Boomerang, MAXIMA DASI measurements cosmic microwave background (CMB) anisotropy power spectra as well their statistical confidence levels are determined a model-independent way. It is shown that Boomerang-2001 data (Netterfield et al. 2001) fixes location amplitude first peak at more than 3σconfidence level. next level above 1σbut below 2σ. 212+/-17, 5426+/-1218μK^2, 544+/-56, 2266+/-607μK^2, 843+/-35,...

The dynamics of expansion and large scale structure formation in the multicomponent Universe with dark energy modeled by minimally coupled scalar field generalized linear barotropic equation state are analyzed. It is shown that past future Universe---eternal accelerated or turnaround collapse---are completely defined current density a relation between its early parameters. clustering properties such models their imprints power spectrum matter perturbations depend on same and, additionally,...

We constrain the parameters of dynamical dark energy in form a classical or tachyonic scalar field with barotropic equation state jointly other cosmological using following combined datasets: CMB power spectra from WMAP7, baryon acoustic oscillations space distribution galaxies SDSS DR7, spectrum luminous red DR7 and light curves SN Ia 2 different compilations: Union2 (SALT2 curve fitting) MLCS2k2 fittings).It has been found that initial value parameter is constrained very weakly by most...

The impact of the Arctic major sudden stratospheric warming (SSW) in 2018 on regional cold weather northern midlatitudes is analyzed. Data from temperature observations East Asia (Changchun, Northern China) and Eastern Europe (Kharkiv, Ukraine) NCEP–NCAR ERA5 reanalyses are used. variability vertical meridional profiles temperature, anomalies, velocities geopotential height during two strong surface cooling events compared. Weather anomalies Changchun Kharkiv appeared under vortex conditions...

We perform an analysis of the Cosmic Web as a complex network, which is built on $Λ$CDM cosmological simulation. For each nodes, are in this case dark matter halos formed simulation, we compute 10 network metrics, characterize role and position node network. The relation these metrics to topological affiliation halo, i.e. type large scale structure, it belongs to, then investigated. In particular, correlation coefficients between topology classes computed. have applied different machine...

We determine the best-fit values and confidence limits for dynamical dark energy parameters together with other cosmological on basis of different datasets which include WMAP9 or Planck-2013 results CMB anisotropy, BAO distance ratios from recent galaxy surveys, magnitude-redshift relations distant SNe Ia SNLS3 Union2.1 samples HST determination Hubble constant. use a Markov Chain Monte Carlo routine to map out likelihood in multi-dimensional parameter space. show that most precise narrowest...

We analyze the possibilities of detecting a signal in hydrogen 21 cm line, which was formed early Universe during Dark Ages cosmological epoch, using Ukrainian radio telescopes UTR-2 and GURT National Academy Sciences Ukraine.As result expansion, this line is shifted to decameter range wavelengths (λ obs ≈ 18 m, ν 16 MHz) band operational frequencies these telescopes.The brightness temperature predicted sky-averaged global ranges from ∼ -0.08 0.02 K, depending on model.Such faint challenge...

We study the formation and destruction of first molecules at epochs Dark Ages Cosmic Dawn to evaluate luminosity protogalaxy clumps (halos) in molecular lines. The cosmological recombination is described using model an effective three-level atom, while chemistry examined relevant basic kinetic equations. then studied effect collisional radiative excitation on intensity emission both warm hot halos. Using Planck data reionization intergalactic medium z~6-8, we evaluated upper limits light...

The development of perturbations number densities ions and electrons during the recombination epoch is analysed. equations for relative ionization fractions were derived from system accurate computation history early Universe. It shown that strong dependence rates on density temperature plasma provides significant deviations amplitudes to those baryon matter adiabatic perturbations. Such are most prominent cosmological scales larger than sound horizon at epoch. protons last scattering...

We study the density distribution of minimally-coupled scalar field dark energy inside a neutron star. The is considered in hydrodynamical representation as perfect fluid with three parameters (background density, equation state, and effective sound speed). star matter modeled unified equations developed by Brussels-Montreal group. With calculated (and its dependence on parameters) we investigate how presence impacts macroscopic characteristics value mass limit for stars. From this impact...

Астрономiчна обсерваторiя Львiвського нацiонального унiверситету

The evolution of scalar linear perturbations is studied in gauge-invariant approach for 2-component models with nonrelativistic matter and minimally coupled fields, the potentials which were constructed either constant dark energy equation state parameter $w$ or its adiabatic sound speed ${c}_{a}^{2}$ equal to zero. numerical solutions show that such fields are almost smoothed out on subhorizon scales. However, they cause scale dependent suppression density decay gravitational potential, can...

The late stages of large-scale structure evolution are treated semianalytically within the framework modified halo model. We suggest a simple yet accurate approximation for relating nonlinear amplitude to linear one spherical density perturbation. For concentration parameter $c$, new computation technique is proposed, which eliminates need interim evaluation ${z}_{\mathrm{col}}$. validity proved $\ensuremath{\Lambda}\mathrm{CDM}$ and $\ensuremath{\Lambda}\mathrm{WDM}$ cosmologies. Also,...

The galaxy data provided by COSMOS survey for 1°×1° field of sky are analysed methods complex networks. Three samples (slices) with redshifts ranging within intervals 0.88÷0.91, 0.91÷0.94, and 0.94÷0.97 studied as two-dimensional projections the spatial distributions galaxies. We construct networks calculate network measures each sample, in order to analyse similarity different samples, distinguish various topological environments, find associations between properties (colour index stellar...