Effect of low anisotropy on cosmological models by using supernova data
Abstract
By using the supernovae type Ia (SNIa) data we study influence of the anisotropy (although low) on the evolution of the universe and compare ΛCDM model with 6 representative parametrizations of the recent Hubble expansion history H(z). To compare these models we use the maximum likelihood method for find that the best fit dynamical w(z) and q(z) obtained from the SNIa dataset. We have performed a comparative analysis of three SNIa datasets such as, the 194 SNIa (0 ≤ z ≤ 1.75), the Supernova Legacy Survey (SNLS) dataset (238 data points 0.15 < z < 1.1) and the most recent Pantheon sample (1048 data points 0.01 < z < 2.3). In particular we find the best fit value of ΛCDM model _{Ωσ0} = 0.013 ± 0.008 , χ_{min}^{2} = 197.56 with 194 SNIa, _{Ωσ0} =  0.003 ± 0.033 , χ_{min}^{2} = 230.656 with 238 SNLS and _{Ωσ0} = 0.011 ± 0.013 , χ_{min}^{2} = 1012.55 with 1048 Pantheon sample. 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_{min}^{2} / dof and ptest to compare different dark energy models. According to both statistical tests and considering anisotropy, the ΛCDM model that is providing the best fit to ΛCDM of FRW model. An even better fit would result with an optimization of the data using effects of anisotropy from the beginning.
 Publication:

New Astronomy
 Pub Date:
 April 2019
 DOI:
 10.1016/j.newast.2018.11.003
 arXiv:
 arXiv:1801.01094
 Bibcode:
 2019NewA...68...65H
 Keywords:

 Anisotropic universe;
 Dark energy;
 Supernovae type ia;
 Luminosity distance;
 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 New Astronomy 68, 65 (2019)