Are Type Ia supernova powerful tool to detect anisotropic expansion of the Universe?
- PDF / 1,644,138 Bytes
- 10 Pages / 595.276 x 790.866 pts Page_size
- 77 Downloads / 174 Views
Regular Article - Theoretical Physics
Are Type Ia supernova powerful tool to detect anisotropic expansion of the Universe? A. Salehi1,a , H. Farajollahi2 , M. Motahari3 , P. Pashamokhtari3 , M. Yarahmadi1, S. Fathi1 1
Department of Physics, Lorestan University, Khorramabad, Iran Western Sydney University, Locked Bag 1791, Penrith, NSW 2751, Australia 3 Department of Physics, University of Guilan, Rasht, Iran
2
Received: 20 December 2019 / Accepted: 22 July 2020 © The Author(s) 2020
Abstract In this paper, we present a detailed analysis of the dark energy dipole using Union2, Pantheon and GRB dataset in Chameleon and Teleparallel dark energy models, in comparison with CDM. Both models are extensively studied in recent years and our result shows that with Union2 and Pantheon data, the preferred direction of the anisotropy in both models are very close to each other as well as with those obtained in some studies for CDM. However, when the models fitted with a combination of Union 2 and GRB, the statistical analysis slightly favors the Chameleon cosmology over Teleparallel gravity, with the maximum anisotropic +30 , b = −15+23 direction of (l = 330−28 −25 ) in galactic coordinate system, comparable with α-dipole result in Keck-VLT data and LCDM.
1 Introduction The standard assumptions of homogeneity and isotropy (namely, the Cosmological Principle) have played an important role in modern cosmology [1]. A large number of cosmological observations such as the cosmic microwave background (CMB) radiation from the Wilkinson Microwave Anisotropy Probes (WMAP) [2,3]. the statistics of the CMB temperature perturbation maps[4] and observations of large scale structure [5–7] generally [5] are in good agreement with CDM model, known as concordance cosmological model [8]. Despite confirmation of CDM model by many observational data, the model is also challenged by some studies [9–40], (see also [23,24] and references therein for more details). Therefore, for further evaluation of the the model, it is necessary to revisit the cosmological principle, by using recent Type Ia supernovae (SNIa) data [8,27] among others. There is always a question whether a variety of new updated a e-mail:
[email protected] (corresponding author)
0123456789().: V,-vol
observational data confirms the universe to be isotropic on large scale, Theoretically, apart from CDM, there are a variety of models that question the isotropic nature of the universe. For example, a vector field may cause cosmic anisotropy and lead the comic to a direction-dependent dark energy [10]. The author of [13] used the hemisphere comparison method to fit the CDM model (and ωCDM model) to the supernovae data and detected a preferred axis at statistically significant level. Reference [16,17] introduced a statistic based on the extreme value theory and applied it to the gold data set of SNIa. They showed that the data is consistent with isotropy and Gaussianity. Reference [20,21] showed that peculiar velocities may generate dipole-like anisotropy, and maximizes the c
Data Loading...
