Using various latest cosmological datasets including type-Ia supernovae, cosmic microwave background radiation, baryon acoustic oscillations, and estimations of the Hubble parameter, we test some dark-energy models wi...Using various latest cosmological datasets including type-Ia supernovae, cosmic microwave background radiation, baryon acoustic oscillations, and estimations of the Hubble parameter, we test some dark-energy models with parameterized equations of state and try to distinguish or select observation-preferred models. We obtain the best fitting results of the six models and calculate their values of the Akaike information criteria and Bayes information criterion. We can distinguish these dark energy models from each other by using these two information criterions. However, the ΛCDM model remains the best fit model. Furthermore, we perform geometric diagnostics including statefinder and Om diagnostics to understand the geometric behavior of the dark energy models. We find that the six dark-energy models can be distinguished from each other and from ΛCDM, Chaplygin gas, quintessence models after the statefinder and Om diagnostics are performed. Finally, we consider the growth factor of the dark-energy models with comparison to the ΛCDM model. Still, we find the models can be distinguished from each other and from the ΛCDM model through the growth factor approximation.展开更多
A scalar field with a pole in its kinetic term is often used to study cosmological inflation;it can also play the role of dark energy,which is called the pole dark energy model.We propose a generalized model where the...A scalar field with a pole in its kinetic term is often used to study cosmological inflation;it can also play the role of dark energy,which is called the pole dark energy model.We propose a generalized model where the scalar field may have two or even multiple poles in the kinetic term,and we call it the multi-pole dark energy.We find that the poles can place some restrictions on the values of the original scalar field with a non-canonical kinetic term.After the transformation to the canonical form,we get a flat potential for the transformed scalar field even if the original field has a steep one.The late-time evolution of the universe is obtained explicitly for the two pole model,while dynamical analysis is performed for the multiple pole model.We find that it does have a stable attractor solution,which corresponds to the universe dominated by the potential of the scalar field.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.11105091)。
文摘Using various latest cosmological datasets including type-Ia supernovae, cosmic microwave background radiation, baryon acoustic oscillations, and estimations of the Hubble parameter, we test some dark-energy models with parameterized equations of state and try to distinguish or select observation-preferred models. We obtain the best fitting results of the six models and calculate their values of the Akaike information criteria and Bayes information criterion. We can distinguish these dark energy models from each other by using these two information criterions. However, the ΛCDM model remains the best fit model. Furthermore, we perform geometric diagnostics including statefinder and Om diagnostics to understand the geometric behavior of the dark energy models. We find that the six dark-energy models can be distinguished from each other and from ΛCDM, Chaplygin gas, quintessence models after the statefinder and Om diagnostics are performed. Finally, we consider the growth factor of the dark-energy models with comparison to the ΛCDM model. Still, we find the models can be distinguished from each other and from the ΛCDM model through the growth factor approximation.
基金Supported by National Science Foundation of China(11105091,11047138)"Chen Guang"project supported by Shanghai Municipal Education Commission and Shanghai Education Development Foundation(12CG51)Shanghai Natural Science Foundation,China(10ZR1422000)。
文摘A scalar field with a pole in its kinetic term is often used to study cosmological inflation;it can also play the role of dark energy,which is called the pole dark energy model.We propose a generalized model where the scalar field may have two or even multiple poles in the kinetic term,and we call it the multi-pole dark energy.We find that the poles can place some restrictions on the values of the original scalar field with a non-canonical kinetic term.After the transformation to the canonical form,we get a flat potential for the transformed scalar field even if the original field has a steep one.The late-time evolution of the universe is obtained explicitly for the two pole model,while dynamical analysis is performed for the multiple pole model.We find that it does have a stable attractor solution,which corresponds to the universe dominated by the potential of the scalar field.
