arXiv subjects

H. Yousefi

Publications and source records attributed to H. Yousefi.

2 recordsLinked to original sources

arXiv2018

Effect of low anisotropy on cosmological models by using supernova data

By using the supernovae type Ia data we study influence of the anisotropy (although low) on the evolution of the universe and compare $Λ$CDM model with 6 representative parametrizations of the recent Hubble expansion history $H(z)$. To compare these models we use the the maximum likelihood method for find that the best fit dynamical $ω(z)$ and $q(z)$ obtained from the SNIa dataset. In particular we find the best fit value of $Λ$CDM model $(Ω_{σ_0}= 0.013$, $χ^2_{min}=197.56)$. The analysis shows that by considering the anisotropy, it leads to more best fit parameters in all models (except of SCDM) with SNIa data. We also use two statistical tests such as the usual $χ^2_{min}/dof$ and p-test to compare different dark energy models. According to both statistical tests and considering anisotropy, the linear parametrization model that is providing the best fit to $Λ$CDM model.

astro-ph.CO↗

arXiv2016

A new approach for solving nonlinear Thomas-Fermi equation based on fractional order of rational Bessel functions

In this paper, the fractional order of rational Bessel functions collocation method (FRBC) to solve Thomas-Fermi equation which is defined in the semi-infinite domain and has singularity at $x = 0$ and its boundary condition occurs at infinity, have been introduced. We solve the problem on semi-infinite domain without any domain truncation or transformation of the domain of the problem to a finite domain. This approach at first, obtains a sequence of linear differential equations by using the quasilinearization method (QLM), then at each iteration solves it by FRBC method. To illustrate the reliability of this work, we compare the numerical results of the present method with some well-known results in other to show that the new method is accurate, efficient and applicable.

math.NA↗