Abstract
In this review paper, several new results towards the explanation of the accelerated expansion of the large-scale universe is discussed. On the other hand, inflation is the early-time accelerated era and the universe is symmetric in the sense of accelerated expansion. The accelerated expansion of is one of the long standing problems in modern cosmology, and physics in general. There are several well defined approaches to solve this problem. One of them is an assumption concerning the existence of dark energy in recent universe. It is believed that dark energy is responsible for antigravity, while dark matter has gravitational nature and is responsible, in general, for structure formation. A different approach is an appropriate modification of general relativity including, for instance, f ( R ) and f ( T ) theories of gravity. On the other hand, attempts to build theories of quantum gravity and assumptions about existence of extra dimensions, possible variability of the gravitational constant and the speed of the light (among others), provide interesting modifications of general relativity applicable to problems of modern cosmology, too. In particular, here two groups of cosmological models are discussed. In the first group the problem of the accelerated expansion of large-scale universe is discussed involving a new idea, named the varying ghost dark energy. On the other hand, the second group contains cosmological models addressed to the same problem involving either new parameterizations of the equation of state parameter of dark energy (like varying polytropic gas), or nonlinear interactions between dark energy and dark matter. Moreover, for cosmological models involving varying ghost dark energy, massless particle creation in appropriate radiation dominated universe (when the background dynamics is due to general relativity) is demonstrated as well. Exploring the nature of the accelerated expansion of the large-scale universe involving generalized holographic dark energy model with a specific Nojiri-Odintsov cut-off is presented to finalize the paper.
Highlights
The accelerated expansion of the large-scale universe (LSU) is one of the long standing problems of physics [1,2,3,4]
In case of two cosmological models having the background dynamics given according to GR, massless particle creation possibility has been demonstrated
There are various attempts to solve this problem and in this review paper one has presented some of the possible new solutions of this problem. It has been demonstrated, that the problem of accelerated expansion can be solved by the new models of the varying ghost dark energy (DE)
Summary
The accelerated expansion of the large-scale universe (LSU) is one of the long standing problems of physics [1,2,3,4]. Discussed models of holographic dark energy models belongs to generalization considered in Reference [24] which allows us to unify symmetry in early universe and LSU in sense of accelerated expansion. Considered cosmological models involve new phenomenological modifications of the ghost DE to explain the accelerated expansion of LSU. The paper is organized as follows: In Section 2, new cosmological models involving various models of the varying ghost dark energy allowing to explain the accelerated expansion of LSU universe are discussed. Massless particle creation has been demonstrated for appropriate radiation dominated expanding universe, which evolves to LSU containing suggested interacting varying ghost DE models.
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