Related papers: Tachyon driven solution to Cosmic Coincidence Prob…
Internal (non-geometric) symmetry is recognized and studied as a new phenomenon in cosmology. Symmetry relates cosmic vacuum to non-vacuum forms of cosmic energies, which are dark matter, baryons, and radiation. It is argued that the origin…
I review the problem of dark energy focusing on the cosmological constant as the candidate and discuss its implications for the nature of gravity. Part 1 briefly overviews the currently popular `concordance cosmology' and summarises the…
Associated with the cosmic acceleration are the old and new cosmological constant problems, recently put into the more general context of the dark energy problem. In broad terms, the old problem is related to an unexpected order of…
Dark and baryonic matter contribute comparable energy density to the present Universe. The dark matter may also be responsible for the cosmic positron/electron excesses. We connect these phenomena with Dirac seesaw for neutrino masses. In…
Recently it has been proposed that the main contributor to the dark energy of the Universe is a dynamical, slow evolving, spatially inhomogeneous scalar field called quintessence. We investigate the behavior of this scalar field at galactic…
Our present understanding of the universe requires the existence of dark matter and dark energy. We describe here a natural mechanism that could make exotic dark matter and possibly dark energy unnecessary. Graviton-graviton interactions…
Taking up four model universes we study the behaviour and contribution of dark energy to the accelerated expansion of the universe, in the modified scale covariant theory of gravitation. Here, it is seen that though this modified theory may…
We show that all cosmological models with an accelerated stationary global attractor reduce asymptotically to a dark energy field with an exponential potential coupled linearly to a perfect fluid dark matter. In such models the abundance of…
Observations seem to indicate that our universe is presently accelerating due to the presence of dark energy. Quintessence represents a possible way to model the dark energy. In these proceedings, we briefly review its main properties.
In the present work, we study the large scale matter power spectrum as well as the observed galaxy power spectrum for non-canonical tachyon field dark energy model considering the full general relativistic perturbation equations. We form a…
We explore quintessence models of dark energy which exhibit non-minimal coupling between the dark matter and the dark energy components of the cosmic fluid. The kind of coupling chosen is inspired in scalar-tensor theories of gravity. We…
Recent cosmological observations strongly suggest that the universe is dominated by an unknown form of energy with negative pressure. Why is this dark energy density of order the critical density today? We propose that the dark energy has…
In this paper is proposed a geometric solution to the dark energy, assuming that the space can be divided into regions of size $\sim L_{p}$ and energy $\sim E_{p}$. Significantly this assumption generate a energy density similar to the…
We derive two field theory models of interacting dark energy, one in which dark energy is associated with the quintessence and another in which it is associated with the tachyon. In both, instead of choosing arbitrarily the potential of…
While there is plentiful evidence in all fronts of experimental cosmology for the existence of a non-vanishing dark energy (DE) density \rho_D in the Universe, we are still far away from having a fundamental understanding of its ultimate…
We uncover the general mechanism producing the dark energy(DE). This is only based on well known quantum physics and cosmology. We show that the observed DE originates from the cosmological quantum vacuum of light particles which provides a…
We consider a model of interacting cosmological constant/quintessence, where dark matter and dark energy behave as, respectively, two coexisting phases of a fluid, a thermally excited Bose component and a condensate, respectively. In a…
Dark energy and dark matter constitute 95% of the observable Universe. Yet the physical nature of these two phenomena remains a mystery. Einstein suggested a long-forgotten solution: gravitationally repulsive negative masses, which drive…
We studied the dilaton cosmology based on Weyl-Scaled induced gravity. The potential of dilaton field is taken as exponential form. An analytical solution of Einstein equation is found. The dilaton can be a candidate for dark energy that…
Cosmology and particle physics are deeply interrelated. Among the common problems are dark energy, dark matter and baryon asymmetry of the Universe. We discuss these problems in general terms, and concentrate on several particular…