Search academic texts

Information × Registration Number 0218U003436, 0117U006354 , R & D reports Title Manifestations of dark energy and dark matter in the modifications of the standard cosmological model. popup.stage_title Head Shtanov Yu. Ivanov, Доктор фізико-математичних наук Registration Date 13-02-2018 Organization Department for special training National academy of science of Ukraine at Kiev University popup.description2 We consider problems connected with the theory of dark energy (DE), dark matter (DM) and modified gravity, including scalar-field (SF) models of DE, and the problem of the large-scale magnetic fields generation in the Universe. We identified physical effects arising in the braneworld model and in the chiral modified gravity. By analyzing spectra of galaxy clusters, an emission line was found at energy ~ 3.55 keV that can be a signal of decaying dark matter. A new semianalytic method was developed for modeling density profiles of fermionic dark matter. We investigate the possibility of generation of large-scale magnetic fields during inflation and preheating in the Starobinsky model due to kinetic coupling of the effective inflaton field with electromagnetic field. We consider the case of exponential coupling function and show that for a certain parameter range it is possible to create large-scale magnetic fields corresponding to the observations at the present epoch. The spectrum of these magnetic fields is blue-tilted. Also, we derive a closed system of equations which governs the coherent evolution of the leptonic asymmetry of the Neutrino modification of the Standard Model and of the spiral magnetic fields in the early Universe. We studied a qualitative behavior of the scale factor and energy density in a hydrodynamic (H) model of a homogeneous isotropic Universe with a general barotropic equation of state. We present a classification of possible scenarios with an asymptotically exponential inflation, analogs of the Big Rip in the future and in the past, singularity-free bouncing solutions and oscillating Universes. The conditions of correspondence between H and SF models of the dynamical dark energy in the homogeneous isotropic Universe are found. In general case, these models are not fully equivalent, although for some SF potentials and some regimes of expansion they yield the same evolution of the energy density and the scale factor as functions of time. We studied a 3-parametric family of exact solutions to Einstein equations with minimally coupled massive SFs. We show that for some family parameters the stable circular orbits of test bodies can form disjoint structures around configurations that describe naked singularities or black holes. Product Description popup.authors Візнюк О.В. Вільчинський С.Й. Жданов В.І. Рудаковський А.В. Руденок І.В. Савченко Д.О. Соболь О.О. Сташко О.С. Штанов Ю.В. popup.nrat_date 2020-04-02 Close