Bianchi Type I Cosmological Models in Eddington-inspired Born–Infeld Gravity

Galaxies

Tiberiu Harko¹  Francisco S.N. Lobo³  Man Kwong Mak² 

[1] Department of Mathematics, University College London, Gower Street, London WC1E 6BT, UK; E-Mail:;Department of Computing and Information Management, Hong Kong Institute of Vocational Education, Chai Wan, Hong Kong, China; E-Mail:;Centro de Astronomia e Astrofísica da Universidade de Lisboa, Campo Grande, Ed. C8 1749-016 Lisboa, Portugal

关键词: Bianchi type I models;    Eddington-inspired Born–Infeld gravity;    modified gravity;    cosmology;   

DOI  :  10.3390/galaxies2040496

来源: mdpi

【 摘 要 】

We consider the dynamics of a barotropic cosmological fluid in an anisotropic, Bianchi type I space-time in Eddington-inspired Born–Infeld (EiBI) gravity. By assuming isotropic pressure distribution, we obtain the general solution of the field equations in an exact parametric form. The behavior of the geometric and thermodynamic parameters of the Bianchi type I Universe is studied, by using both analytical and numerical methods, for some classes of high density matter, described by the stiff causal, radiation, and pressureless fluid equations of state. In all cases the study of the models with different equations of state can be reduced to the integration of a highly nonlinear second order ordinary differential equation for the energy density. The time evolution of the anisotropic Bianchi type I Universe strongly depends on the initial values of the energy density and of the Hubble function. An important observational parameter, the mean anisotropy parameter, is also studied in detail, and we show that for the dust filled Universe the cosmological evolution always ends into isotropic phase, while for high density matter filled universes the isotropization of Bianchi type I universes is essentially determined by the initial conditions of the energy density.

【 授权许可】

CC BY   
© 2014 by the authors; licensee MDPI, Basel, Switzerland.