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We explore the dynamics of dark energy models based on a Dirac-Born-Infeld (DBI) tachyonic action, studying a range of potentials. We numerically investigate the existence of tracking behaviour and determine the present-day value of the…
We analyse the evolution of scalar and gauge fields during a second order phase transition using a Langevin equation approach. We show that topological defects formed during the phase transition are stable to thermal fluctuations. Our…
We investigate cosmological consequences of a generalized early dark energy (EDE) model where a scalar field behaves as dark energy at various cosmological epochs for a broad range of parameters such as the energy scale and the initial…
We study the perturbed equation of state (EOS) parameters of the cosmological tachyonic scalar field components and their mutual time-dependent interaction. It is shown that the discrete temperature-dependent pattern of the EOS emerges from…
Cosmological scaling solutions, which give rise to a scalar-field density proportional to a background fluid density during radiation and matter eras, are attractive to alleviate the energy scale problem of dark energy. In the presence of…
Determining the mechanism behind the current cosmic acceleration constitutes a major question nowadays in theoretical physics. If the dark energy route is taken, this problem may potentially bring to light new insights not only in Cosmology…
In this work we investigate the polytropic gas dark energy model in the non flat universe. We first calculate the evolution of EoS parameter of the model as well as the cosmological evolution of Hubble parameter in the context of polytropic…
We study Galileon scalar field model by considering the lowest order Galileon term in the lagrangian, $(\partial_{\mu} \phi)^2 \Box\phi$ by invoking a field potential. We use Statefinder hierarchy to distinguish the light mass galileon…
Neutrinos coupled to an underlying scalar field in the scenario for unification of mass varying dark matter and cosmon-{\em like} dark energy is examined. In the presence of a tiny component of mass varying neutrinos, the conditions for the…
In this study, we introduce a novel late-time effective dark energy model characterized by a quadratic equation of state (EoS) and rigorously examine its observational constraints. Initially, we delve into the background dynamics of this…
Although the standard cosmological model is capable of explaining most current observational data, it faces some theoretical and observational issues. This is the main motivation for exploring alternative cosmological models. In this paper,…
We present a realistic scenario of tracking of scalar fields with varying equation of state. The astrophysical constraints on the evolution of scalar fields in the physical universe are discussed. The nucleosynthesis and the galaxy…
Time-varying dark energy is often modeled in observational analyses through generic parameterizations of its equation of state $w(z)$, which typically use two free parameters $\{w_0, w_a\}$ to span a broad range of behaviors as a function…
In this paper we investigate the role played by dark energy in the form of Generalized cosmic Chaplygin gas in an accelerating universe described by FRW cosmology. We have tried to describe the model from the theoretical point of view of a…
The evolution of scalar linear perturbations is studied in gauge-invariant approach for 2-component models with nonrelativistic matter and minimally coupled scalar fields, the potentials of which were constructed for either constant dark…
We place observational constraints on models with the late-time cosmic acceleration based on a number of parametrizations allowing fast transitions for the equation of state of dark energy. In addition to the model of Linder and Huterer…
We review the essential features of the Chaplygin gas cosmological models and provide some examples of appearance of the Chaplygin gas equation of state in modern physics. A possible theoretical basis for the Chaplygin gas in cosmology is…
The equation of state (EOS) of the dark energy is the key parameter to study the nature of the dark energy from the observation. Though the dark energy is found to be well consistent with the cosmological constant with a constant EOS of…
This study explores the dynamics and phase-space behavior of a multi-component dark energy model, where the dark sector consists of a minimally coupled canonical scalar field and the cosmological constant, using a dynamical system analysis…
In the past few years, $f(Q)$ theories have drawn a lot of research attention in replacing Einstein's theory of gravity successfully. The current study examines the novel cosmological possibilities emerging from two specific classes of…