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Ahmad Mehrabi

Ahmad Mehrabi

Academic rank: Associate Professor
ORCID:
Education: PhD.
ScopusId: 36705117200
HIndex:
Faculty: Faculty of Science
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Research

Title
Growth of perturbations in dark energy parametrization scenarios
Type
JournalPaper
Keywords
Dark energy
Year
2018
Journal PHYSICAL REVIEW D
DOI
Researchers Ahmad Mehrabi

Abstract

In this paper, we study the evolution of dark matter perturbations in the linear regime by considering the possibility of dark energy perturbations. To do this, two popular parametrizations, Chevallier-Polarski-Linder (CPL) and Barboza-Alcaniz (BA), with the same number of free parameters and different redshift dependency have been considered. We integrate the full relativistic equations to obtain the growth of matter fluctuations for both clustering and smooth versions of CPL and BA dark energy. The growth rate is larger (smaller) than the ΛCDM in the smooth cases when w < −1 (w > −1), but the dark energy clustering gives a larger (smaller) growth index when w > −1 (w < −1). We measure the relative difference of the growth rate with respect to concordance ΛCDM and study how it changes depending on the free parameters. Furthermore, it is found that the difference of growth rates between smooth CPL and BA is negligible, less than 0.5%, while for the clustering case, the difference is considerable and might be as large as 2%. Eventually, using the latest geometrical and growth rate observational data, we perform an overall likelihood analysis and show that both smooth and clustering cases of CPL and BA parametrizations are consistent with observations. In particular, we find the dark energy figure of merit is approximately 70 for the BA and approximately 30 for the CPL, which indicates the BA model constrains relatively better than the CPL one.