Related papers: Quadratic Dark Energy Phase-Space Dynamics and Ana…
In this paper, applying the Hartman-Grobman theorem we carry out a qualitative late-time analysis of some unified dark energy-matter Friedmann cosmological models, where the two interact through linear energy exchanges, and the dark energy…
Hubble constant($H_0$) tension and tension in the matter fluctuation amplitude ($s_8$) are fascinating puzzles in cosmology nowadays. Phantom dynamical dark energy model (PDDE), also known as little sibling of the big rip is an abrupt event…
Recent cosmological data, including DESI DR2, highlight significant tensions within the $\Lambda$CDM paradigm. When analyzed in the context of General Relativity (GR), the latest DESI data favor a dynamical dark energy (DDE) equation of…
The difference between vacuum energy of quantum fields in Minkowski space and in Friedmann-Robterson-Walker universe might be related to the observed dark energy. The vacuum energy of the Veneziano ghost field introduced to solve the…
In observational cosmology, the dark energy density and equation of state are effective quantities reconstructed at the background level under a set of assumptions. These include the FLRW framework, the standard Friedmann equation of…
Using the generalized Tsallis entropy, the Tsallis holographic dark energy(THDE) was proposed recently. In this paper we analyze the cosmological consequences of the THDE model with an interaction between dark energy and dark matter…
Motivated by the recent Dark Energy Spectroscopic Instrument (DESI) DR2 preference for dynamical dark energy, we study interacting dark energy models in which a canonical quintessence field couples to cold dark matter through a…
Considering that the universe is filled with the nonrelativistic matter and dark energy and each component is respectively satisfied with its conservation condition in the absence of their interaction, we give the change rate of the…
We apply the formalism of dynamical system analysis to investigate the evolution of interacting dark energy scenarios at the background and perturbation levels in a unified way. Since the resulting dynamical system contains the extra…
The Dark Energy Spectroscopic Instrument (DESI) second data release shows a moderate preference for dark energy with a time-varying equation of state parameter, suggesting that the standard $\Lambda$CDM model may need to be revised. In…
Phantom fields with negative kinetic energy are often plagued by the vacuum quantum instability in the ultraviolet region. We present a Lorentz-violating dark energy model free from this problem and show that the crossing of the…
We investigate the late-time cosmological dynamics in a simple case of explicit spacetime-symmetry breaking. By expanding in a small symmetry-breaking coefficient we are able to write the Friedmann equations as $\Lambda$CDM + dynamical dark…
We investigate the phase-space structure of the quintom dark energy paradigm in the framework of spatially flat and homogeneous universe. Considering arbitrary decoupled potentials, we find certain general conditions under which the phantom…
A pressureless dark matter component fits well with several cosmological observations. However, there are indications that cold dark matter may encounter challenges in explaining observations at small scales, particularly at galactic…
We investigate whether the recent DESI DR2 measurements provide or not evidences for dynamical dark energy by exploring the $\omega_0\omega_a$CDM model and its extensions with free $\sum m_{\nu}$ and $N_{\mathrm{eff}}$. Using a…
We explore an extension of the $\Lambda$CDM model in which the pressure $p$ of the dark energy (DE) fluid evolves with the expansion of the Universe, expressed as a function of the scale factor $a$. The corresponding energy density $\rho$…
The wave equation with energy critical sources and nonlinear damping defined on a 3D bounded domain is considered. It is shown that the resulting dynamical system admits a global attractor. Under the additional assumption of strong…
Cosmological models exhibiting crossing of the phantom divide improve the fit to current data, suggesting late-time dark energy (DE) dynamics at $\sim3\sigma$ CL. However, they favor low values of $H_0$, in tension with SH0ES. This may…
Recent analyses in the literature suggest that the concordance $\Lambda$CDM model with rigid cosmological term, $\Lambda=$const., may not be the best description of the cosmic acceleration. The class of "running vacuum models", in which…
There is mounting evidence from multiple cosmological probes that dark energy may be dynamical, with an equation of state that evolves over cosmic time. While this evidence is typically quantified using the Chevallier-Polarski-Linder (CPL)…