The locally rotationally symmetric Bianchi-type II string cosmological models with bulk viscosity are obtained, where an equation of state, , and a relation between metric potentials, , are adopted. The physical featu...The locally rotationally symmetric Bianchi-type II string cosmological models with bulk viscosity are obtained, where an equation of state, , and a relation between metric potentials, , are adopted. The physical features of the models are also discussed. In special cases the model reduces to the string models without viscosity that was previously given in the literatures.展开更多
With the dark energy phenomena explored over a decade, in this present work we discuss a specific case of the generalized Einstein-aether theories, in which the modified Friedmann equation is similar to that in the Dv...With the dark energy phenomena explored over a decade, in this present work we discuss a specific case of the generalized Einstein-aether theories, in which the modified Friedmann equation is similar to that in the Dvali- Gabadadze-Porrati （DGP） brahe world model. We compute the joint statistic constraints on model parameters in this specific case by using the recent type Ia supernovae （SNe Ia） data, the cosmic microwave background （CMB） shift parameter data, and the baryonic acoustic oscillations （BAOs） data traced by the S1oan Digital Sky Survey （SDSS）. Furthermore, we analyze other constrains from the observational Hubble parameter data （OHD）. The comparison with the standard cosmological model （cosmological constant A cold dark matter （ACDM） model） is dearly shown; also we comment on the interesting relation between the coupling constant M in this model and the special accelerate scale in the modified Newtonian dynamies （MOND） model initially given by Milgrom with the hope for interpreting the galaxy rotation curves without introducing mysterious dark matter.展开更多
文摘The locally rotationally symmetric Bianchi-type II string cosmological models with bulk viscosity are obtained, where an equation of state, , and a relation between metric potentials, , are adopted. The physical features of the models are also discussed. In special cases the model reduces to the string models without viscosity that was previously given in the literatures.
基金Supported by Natural Science Foundation of China under Grant Nos. 11075078 and 10675062by the project of knowledge Innovation Program (PKIP) of Chinese Academy of Sciences (CAS) under Grant No. KJCX2.YW.W10 through the KITPC astrophysics and cosmology programmes where we have initiated this present work
文摘With the dark energy phenomena explored over a decade, in this present work we discuss a specific case of the generalized Einstein-aether theories, in which the modified Friedmann equation is similar to that in the Dvali- Gabadadze-Porrati （DGP） brahe world model. We compute the joint statistic constraints on model parameters in this specific case by using the recent type Ia supernovae （SNe Ia） data, the cosmic microwave background （CMB） shift parameter data, and the baryonic acoustic oscillations （BAOs） data traced by the S1oan Digital Sky Survey （SDSS）. Furthermore, we analyze other constrains from the observational Hubble parameter data （OHD）. The comparison with the standard cosmological model （cosmological constant A cold dark matter （ACDM） model） is dearly shown; also we comment on the interesting relation between the coupling constant M in this model and the special accelerate scale in the modified Newtonian dynamies （MOND） model initially given by Milgrom with the hope for interpreting the galaxy rotation curves without introducing mysterious dark matter.
