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A Tracker Solution for a Holographic Dark Energy Model

Hui Li,b; Zong-Kuan Guo; Yuan-Zhong ZhangSubjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

We investigate a kind of holographic dark energy model with the future event horizon the IR cutoff and the equation of state ?1. In this model, the constraint on the equation of state automatically specifies an interaction between matter and dark energy. With this interaction included, an accelerating expansion is obtained as well as the transition from deceleration to acceleration. It is found that there exists a stable tracker solution for the numerical parameter d > 1, and d smaller than one will not lead to a physical solution. This model provides another possible phenomenological framework to alleviate the cosmological coincidence problem in the context of holographic dark energy. Some properties of the evolution which are relevant to cosmological parameters are also discussed. |

Parametrization of K-essence and Its Kinetic Term

Hui Li; Zong-Kuan Guo; Yuan-Zhong ZhangSubjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

We construct the non-canonical kinetic term of a k-essence field directly from the effective equation of state function wk(z), which describes the properties of the dark energy.Adopting the usual parametrizations of equation of state we numerically reproduce the shape of the non-canonical kinetic term and discuss some features of the constructed form of k-essence. |

PLASMA HEATING INSIDE ICMES BY ALFV?ENIC FLUCTUATIONS DISSIPATION

Hui Li; Chi Wang; Jiansen He; Lingqian Zhang; John D. Richardson; John W. Belcher; Cui TuSubjects: Geosciences >> Space Physics

Nonlinear cascade of low-frequency Alfvenic fluctuations (AFs) is regarded as one candidate of the energy sources to heat plasma during the non-adiabatic expansion of interplanetary coronal mass ejections (ICMEs). However, AFs inside ICMEs were seldom reported in the literature. In this study, we investigate AFs inside ICMEs using observations from Voyager 2 between 1 and 6 au. It is found that AFs with high degree of Alfvenicity frequently occurred inside ICMEs, for almost all the identified ICMEs (30 out of 33 ICMEs), and 12.6% of ICME time interval. As ICMEs expand and move outward, the percentage of AF duration decays linearly in general. The occurrence rate of AFs inside ICMEs is much less than that in ambient solar wind, especially within 4 au. AFs inside ICMEs are more frequently presented in the center and at the boundaries of ICMEs. In addition, the proton temperature inside ICME has a similar distribution. These findings suggest significant contribution of AFs on local plasma heating inside ICMEs. |

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