Related papers: Testing the EoS of dark matter with cosmological o…
Although $\Lambda$CDM model is very successful in many aspects, it has been seriously challenged. Recently, warm dark matter (WDM) remarkably rose as an alternative of cold dark matter (CDM). In the literature, many attempts have been made…
This study investigates the potential of a cosmological model termed $\Lambda w$DM, in which a cosmological constant play the role of dark energy and dark matter is barotropic and has a constant equation of state parameter ($w_{\rm dm}$),…
This article questions the common assumption of cold dark matter (DM) by exploring the possibility of a non-zero equation of state (EoS) without relying on any parametric approach. In standard cosmological analyses, DM is typically modeled…
Recent observations of DESI hint that dark matter (DM) may not be cold but have a non-zero equation of state (EoS) parameter, and that dark energy (DE) may not be a cosmological constant. In this work, we explore the possibility of a…
In this paper, we set the new limits on the equation of state parameter (EoS) of dark energy with the observations of cosmic microwave background radiation (CMB) from Planck satellite, the type Ia supernovae from Pan-STARRS and the baryon…
We revisit a cosmological model where dark matter (DM) and dark energy (DE) follow barotropic equations of state, allowing deviations from the standard $\Lambda$CDM framework (i.e. $w_{dm} \neq 0$, $w_{de} \neq -1$), considering both flat…
The nature of dark matter remains one of the most fundamental and unresolved questions in modern cosmology. In most cosmological models, dark matter is typically modeled as pressureless dust with an equation of state (EoS) parameter $w_{\rm…
In this paper, we combine the latest observational data, including the WMAP five-year data (WMAP5), BOOMERanG, CBI, VSA, ACBAR, as well as the Baryon Acoustic Oscillations (BAO) and Type Ia Supernoave (SN) "Union" compilation (307 sample)…
Soft cosmology is an extension of standard cosmology allowing for a scale-dependent equation-of-state (EoS) parameter in the dark sectors, which is one of the properties of soft materials in condensed-matter physics, that may arise either…
While cold dark matter is widely supported by a range of cosmological observations, it encounters several difficulties at smaller scales. These issues have prompted the investigation of various alternative dark matter candidates, leaving…
A new parameterization for the dark energy equation of state(EoS) is proposed and some of its cosmological consequences are also investigated. This new parameterization is the modification of Efstathiou' dark energy EoS parameterization. $w…
Physical limits on the equation-of-state (EoS) parameter of a dark energy component non-minimally coupled with the dark matter field are examined in light of the second law of thermodynamics and the positiveness of entropy. Such constraints…
We propose a new cosmological model that considers dark matter as a barotropic fluid with a constant equation of state parameter and interprets dark energy as the phenomenological emergent dark energy rather than a cosmological constant.…
In this article, we investigate a new parametrization of the dark energy equation of state (EoS) with a single parameter for a barotropic fluid that deviates from the standard $\Lambda$CDM cosmology. We derive observational constraints on…
We critically examine the state of current constraints on the dark energy (DE) equation of state (EoS) $w$. Our study is motivated by the observation that, while broadly consistent with the cosmological constant value $w=-1$, several…
In this paper we study the evolution of cosmological perturbations in the presence of dynamical dark energy, and revisit the issue of dark energy perturbations. For a generally parameterized equation of state (EoS) such as w_D(z) =…
We propose and implement a novel test to assess deviations from well-established concordance $\Lambda$CDM cosmology while inferring dark energy properties. In contrast to the commonly implemented parametric forms of the dark energy…
In this work, we propose a non-standard dark matter (NSDM) model in which the equation of state (EoS) of dark matter (DM) is parameterized as $w_{\rm dm} = w_2 a^2$, and this DM model is motivated by the idea that DM must become cold dark…
We present a parametrization for the Dark Energy Equation of State "EoS" which has a rich structure, performing a transition at pivotal redshift $z_T$ between the present day value $w_0$ to an early time $w_i=w_a+w_0\equiv w(z\gg0)$ with a…
We consider the hypothesis that dark energy and dark matter are the two faces of a single dark component, a unified dark matter (UDM) that we assume can be modeled by the affine equation of state (EoS) $P= p_0 +\alpha \rho$, resulting in an…