arXiv subjects

Ehsan Sadri

Publications and source records attributed to Ehsan Sadri.

7 recordsLinked to original sources

arXiv2021

Observational constraints on interacting Tsallis holographic dark energy models

In this paper, we investigate a recent proposed model - so called the Tsallis holographic dark energy (THDE) model. In this case, we consider the non-gravitational and phenomenological interaction between dark sectors. We fit the free parameters of the model using Pantheon Supernovae Type Ia data, Baryon Acoustic Oscillations, Cosmic Microwave Background, Gamma-Ray burst and the the local value of the Hubble constant. We examine the THDE model to check its compatibility with observational data using objective Information Criterion (IC). We find that the THDE model cannot be supported by observational data. Using the Alcock-Paczynski (AP) test we check the deviation of the model compared to $Λ$CDM. Surveying the evolution of squared of sound speed $v^2_s$ as an another test we check the stability of the interacting and non-interacting THDE models. In addition, using the modified version of the CAMB package, we observe the suppressing the CMB spectrum at small K-modes and large scale.

astro-ph.CO↗

arXiv2020

Scrutinizing Various Phenomenological Interactions In The Context Of Holographic Ricci Dark Energy Models

In this paper, we examine two types of interacting holographic dark energy model using Pantheon supernova data, BAO BOSS DR12, CMB Planck 2015, fgas (gas mass fraction) and SZ/Xray (Sunyaev-Zeldovich effect and X-ray emission) data from galaxy clusters (GC). In particular, we considered the Holographic Ricci dark energy and Extended holographic Ricci dark energy models. During this analysis we considered seven type of phenomenological interaction terms (three linear and four non-linear) $Q_1=3Hbρ_{D}$, $Q_2=3Hbρ_{m}$, $Q_3=3Hb\left(ρ_{D}+ρ_m\right)$, $Q_4=3Hb\left(ρ_{D}+\frac{ρ_{D}^2}{ρ_{D}+ρ_m}\right)$, $Q_5=3Hb\left(ρ_{m}+\frac{ρ_{m}^2}{ρ_{D}+ρ_m}\right)$, $Q_6=3Hb\left(ρ_{D}+ρ_{m}+\frac{ρ_{D}^2}{ρ_{D}+ρ_m}\right)$, $Q_7=3Hb\left(ρ_{D}+ρ_{m}+\frac{ρ_{m}^2}{ρ_{D}+ρ_m}\right)$ respectively. To find the best model we apply Akaike Information Criterion (AIC) and Bayesian Information Criterion (BIC) and use the $Λ$CDM as the referring model for comparison. Using AIC and BIC models selection method we note that the $Q_1$ and $Q_4$ interaction terms are favored by observational data within the context of the holographic Ricci dark energy models. The obtained results also demonstrated that the considered types of holographic Ricci dark energy model are not favored by observational data since the $Λ$CDM is considered as the reference model. We also observed that the values of the deceleration parameter and the transition redshift for all models are compatible with the latest observational data and Planck 2015. In addition, we studied the jerk parameter for all models. Using our modified CAMB code, we observed that the interacting models suppress the CMB spectrum at low multi-poles and enhances the acoustic peaks.

gr-qc↗

arXiv2019

On An Interacting New Holographic Dark Energy Model: observational constraints

In this paper, we study the interacting DGP braneworld Holographic Dark Energy model in a spatially flat FRW universe. Mainly, in this study we concentrate our attention on both interacting and non-interacting form of the model. The study shows that the equation of state and the deceleration parameter depict an accelerated universe for all variety of interactions. On the other hand, the StateFinder analysis shows that of the interacting and non-interacting behave similar to both quintessence and phantom dark energy and for the present value obey the behavior of quintessence. Moreover, the result of $Om$-diagnostic is an emphasis on the result of the equation of state showing that the current model is in the quintessence are with Phantom-like behavior in the late time. By the use of the squared sound speed $v^2_s$ we find that the present mode has a good stability. In order to obtain the best fit values of the parameters in this work we used the latest observational data (Pantheon, Boss DR12 and Planck 2015) implementing MCMC method by the use of EMCEE python package. We also employ Akaike Information Criterion (AIC) and Bayesian Information Criterion (BIC) model selection tools and compare the model with $Λ$CDM as the reference model.

gr-qc↗

arXiv2018

An interacting New Holographic Dark Energy in the framework of fractal cosmology

In this paper, we study an interacting holographic dark energy model in the framework of fractal cosmology. The features of fractal cosmology could pass ultraviolet divergencies and also make a better understanding of the universe in different dimensions. We discuss a fractal FRW universe filled with the dark energy and cold dark matter interacting with each other. It is observed that the Hubble parameter embraces the recent observational range while the deceleration parameter demonstrates an accelerating universe and a behavior similar to $Λ$CDM. Plotting the equation of state shows that it lies in phantom region for interaction mode. We use $Om$-diagnostic tool and it shows a phantom behavior of dark energy which is a condition of avoiding the formation of black holes. Finally we execute the StateFinder diagnostic pair and all the trajectories for interacting and non-interacting state of the model meet the fixed point $Λ$CDM at the start of the evolution. A behavior similar to Chaplygin gas also can be observed in statefinder plane. We find that new holographic dark energy model (NHDE) in fractal cosmology expressed the consistent behavior with recent observational data and can be considered as a model to avoid the formation of black holes in comparison with the main model of NHDE in the simple FRW universe. It has also been observed that for the interaction term varying with matter density, the model generates asymptotic de-Sitter solution. However, if the interaction term varies with energy density, then the model shows Big-Rip singularity. Using our modified CAMB code, we observed that the interacting model suppresses the CMB spectrum at low multipoles $l<50$ and enhances the acoustic peaks. Based on the observational data sets used in this paper and using Metropolis-Hastings method of MCMC numerical calculation, ...

gr-qc↗

arXiv2017

A new holographic dark energy model in Brans-Dicke theory with logarithmic scalar field

We study a holographic dark energy model in the framework of Brans-Dicke (BD) theory with taking into account the interaction between dark matter and holographic dark energy. We use the recent observational data sets, namely SN Ia compressed Joint Light-Analysis(cJLA) compilation, Baryon Acoustic Oscillations (BAO) from BOSS DR12 and the Cosmic Microwave Background (CMB) of Planck 2015. After calculating the evolution of the equation of state as well as the deceleration parameters, we find that with a logarithmic form for the BD scalar field the phantom crossing can be achieved in the late time of cosmic evolution. Unlike the conventional theory of holographic dark energy in standard cosmology ($ω_D=0$), our model results a late time accelerated expansion. It is also shown that the cosmic coincidence problem may be resolved in the proposed model. We execute the statefinder and Om diagnostic tools and demonstrate that interaction term does not play a significant role. Based on the observational data sets used in this paper it seems that the best value with $1σ$ and $2σ$ confidence interval are $Ω_m=0.268^{+0.008~+0.010}_{-0.007~-0.009}$, $ α=3.361^{+0.332~+0.483}_{-0.401~-0.522}$, $β=5.560^{+0.541~+0.780}_{-0.510~-0.729}$, $c=0.777^{+0.023~+0.029}_{-0.017~-0.023}$ and $b^2 =0.045$, according to which we find that the proposed model in the presence of interaction is compatible with the recent observational data.

astro-ph.CO↗

arXiv2017

An analysis of the expansion acceleration of the Universe in the Interacting Holographic Dark Energy model

Holographic model is originated from Holographic principle. The equation of state in Holographic model and Einstein's gravity with particle horizon can be obtained as wD>-1/3 and cannot justify the expansion acceleration of the Universe. But, by using the event horizon, this model can result in the accelerating expansion in Einstein's gravity and Brans-Dicke cosmology. In this context, we study the holographic model with apparent horizon satisfying the acceleration expansion. We shall see, in the presence of interaction, phase change and transition from decelerated state to accelerated state is possible. This shows the sign of deceleration parameter.

gr-qc↗

arXiv2017

An analogy between four parametrizations of the dark energy equation of state onto Physical DE Models

In order to scrutinize the nature of Dark Energy, many Equations of State have been proposed. In this context we examine four popular models (the Chevallier-Polarski-Linder (CPL) model, Jassal model, Barboza & Alcaniz model and Wetterich model) in the field of quintessence and barotropic dark energy models, to compare with each other. We develop a theoretical method of constructing the quintessence potential directly from the four equations of state which describes the properties of the dark energy.

gr-qc↗