Related papers: Observational Constraints on the Structure-Induced…
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…
By assuming a phenomenological form for the ratio of the DE and DM densities $\rho_X\propto \rho_{m} a^{\xi}$ (Dalal et al.2001), we discuss the cosmic coincidence problem in light of current observational data. $\xi$ is a key parameter to…
Although the cosmic concordance cosmology is quite successful in fitting data, fine tuning and coincidence problems apparently weaken it. We review several possibilities to ease its problems, by considering various kinds of dynamical Dark…
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…
The exact solution for dynamic of conform-flat space homogeneous since dynamic equation is given. Conform mode of space metric changing in Global time theory has negative energy density. Swap of energy to this mode from another ones lead to…
Despite the fact that the $\Lambda$CDM model has been highly successful over the last few decades in providing an accurate fit to a broad range of cosmological and astrophysical observations, different intriguing tensions and anomalies…
We study dynamical behaviors of the dark energy models interacting with dark matter and unparticle in the standard flat FRW cosmology. We considered four different interacting models and examined the stability of the critical points. We…
In this study, cosmological models are considered, where dark matter and dark energy are coupled and may exchange energy through non-gravitational interactions with one other. These interacting dark energy (IDE) models have previously been…
We use the effective field theory of dark energy to explore the space of modified gravity models which are capable of driving the present cosmic acceleration. We identify five universal functions of cosmic time that are enough to describe a…
We carry out an independent re-analysis of the Dark Energy Spectroscopic Instrument (DESI) public dataset, focusing on extensions to the standard cosmological model, $\Lambda$CDM. Utilizing the dataset and Effective Field Theory (EFT)-based…
A phenomenological model of dark energy that tracks the baryonic and cold dark matter at early times but resembles a cosmological constant at late times is explored. In the transition between these two regimes, the dark energy density drops…
In this paper, we investigate a quintessence field with an exponential potential motivated by the suggestion of time-varying dark energy from the DESI galaxy survey. Assuming a kination epoch in the early Universe, we analytically derive…
The possibility of linking inflation and late cosmic accelerated expansion using the $\alpha$-attractor models has received increasing attention due to their physical motivation. In the early universe, $\alpha$-attractors provide an…
A model of cosmology, that arises from the hypothesis that ordinary matter, dark matter and dark energy are made of the same stuff, is studied. It is argued that this hypothesis is a consequence of considering space and time in the same…
This paper makes the simple observation that a fundamental length, or cutoff, in the context of Friedmann-Lema\^itre-Robertson-Walker (FRW) cosmology implies very different things than for a static universe. It is argued that it is…
A phenomenological formalism is presented in which the apparent acceleration of the universe is generated by large-scale structure formation, thus eliminating the coincidence and magnitude fine-tuning problems of the Cosmological Constant…
This thesis focuses on late-time cosmic acceleration within modified theories of gravity, using various observational data sets and statistical analysis. The Universe is assumed to be spatially homogeneous and isotropic and is described by…
Within the context of standard cosmology, an accelerating universe requires the presence of a third `dark' component of energy, beyond matter and radiation. The available data, however, are still deemed insufficient to distinguish between…
A range of cosmological observations demonstrate an accelerated expansion of the Universe, and the most likely explanation of this phenomenon is a cosmological constant. Given the importance of understanding the underlying physics, it is…
The energy scale of Dark Energy, $\sim 2 \times 10^{-3}$ eV, is a long way off compared to all known fundamental scales - except for the neutrino masses. If Dark Energy is dynamical and couples to neutrinos, this is no longer a coincidence.…