Related papers: Modeling galactic halos with predominantly quintes…
In the paper, we apply the weak gravity conjecture to the holographic quintessence model of dark energy. Three different holographic dark energy models are considered: without the interaction in the non-flat universe; with interaction in…
We investigate the effects of chameleon scalar field to the effective density and pressure of a dark matter halo. The pressure is generated from the chameleonic fifth force on the matter. We demonstrate that the thick-shell non-singular…
We analyze the behavior of the scalar field as dark energy of the Universe in a static world of galaxies and clusters of galaxies. We find the analytical solutions of evolution equations of the density and velocity perturbations of dark…
A simple gravitational model with torsion is studied, and it is suggested that it could explain the dark matter and dark energy in the universe. It can be reinterpreted as a model using the Einstein gravitational equations where spacetime…
In this work, we study a new quintessence model associated with non-Abelian gauge fields, minimally coupled to Einstein gravity. This gauge theory has been recently introduced and studied as an inflationary model, called gauge-flation.…
The idea is considered that a classical non-Abelian gauge field can be considered as a dark matter candidate. It is shown that Yang-Mills equations have solutions with such distribution of the mass density that allows to describe a…
The determination of the velocities, accelerations and the gravitational field intensity at a given location in a galaxy could potentially be achieved in an unexpected manner with the environment of the observer, for instance, the local…
In this work we study the magnitude-redshift relation of a non-standard cosmological model. The model under consideration was firstly investigated within a special case of metric-affine gravity (MAG) and was recently recovered via different…
A new family of nonrelativistic, Newtonian, non-quantum equilibrium configurations describing galactic halos is introduced, by considering strange quark matter conglomerates with masses larger than about 8 GeV as new possible components of…
We critically reexamine two possible Dark Matter candidate within the Standard Model. First, we consider the $uuddss$ exa-quark. Its QCD binding energy could be large enough to make it (quasi) stable. We show that the cosmological Dark…
Particle physics candidates for cosmological dark matter are usually considered as neutral and weakly interacting. However stable charged leptons and quarks can also exist and, hidden in elusive atoms, play the role of dark matter. The…
We study the dynamics of dark energy in the presence of a 2-form field coupled to a canonical scalar field $\phi$. We consider the coupling proportional to $e^{-\mu \phi/M_{\rm pl}} H_{\alpha \beta \gamma}H^{\alpha \beta \gamma}$ and the…
We revisit the phenomenology of quintessence models in light of the recently refined version of the de Sitter Swampland conjecture, which includes the possibility of unstable de Sitter critical points. We show that models of quintessence…
Observations of density profiles of galaxies and clusters constrain the properties of dark matter. Formation of stable halos by collisional fluids with very low mass particles appears as the most probable interpretation, while halos formed…
We use linear and quasi-linear perturbation theory to analyse cold dark matter models of structure formation in spatially flat models with a cosmological constant. Both a tilted spectrum of density perturbations and a significant…
The fact that the energy densities of dark energy and matter are similar currently, known as the coincidence problem, is one of the main unsolved problems of cosmology. We present here a model in which a spatial curvature of the universe…
We have constructed star models consisting of four parts: (i) a homogeneous inner core with anisotropic pressure (ii) an infinitesimal thin shell separating the core and the envelope; (iii) an envelope of inhomogeneous density and isotropic…
We investigate a class of models for dark matter and/or negative-pressure, dynamical dark energy consisting of ``spintessence,'' a complex scalar field $\phi$ spinning in a U(1)-symmetric potential $V(\phi)=V(|\phi|)$. As the Universe…
Coherent oscillations of a scalar field can mimic the behavior of a perfect fluid with an equation-of-state parameter determined by the properties of the potential, possibly driving accelerated expansion in the early Universe (inflation)…
We discuss variants of Cold Dark Matter (CDM) dominated cosmological models that give good agreement with a range of observations. We consider models with hot dark matter, tilt, $\Omega < 1$, or a cosmological constant. We also discuss the…