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Cosmological Evolution of Interacting Phantom Energy with Dark Matter

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

We investigate the cosmological evolution of an interacting phantom energy model in which the phantom field has interaction with the dark matter. We discuss the existence and stability of scaling solutions for two types of specific interactions. One is motivated by the conformal transformation in string theory and the other is motivated by analogy with dissipation. In the former case, there exist no scaling solutions. In the latter case, there exist stable scaling solutions, which may give a phenomenological solution of the coincidence problem. Furthermore, the universe either accelerates forever or ends with a singularity, which is determined by not only the model parameters but also the initial velocity of the phantom field. |

Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

We investigate the role of a suitable interaction between a matter fluid and a phantom field for the coincidence problem. There exists a stationary scaling solution which is a stable attractor at late times. Furthermore, the cosmic doomsday is avoided in one region of the parameter space |

Cosmological Evolution of a Quintom Model of Dark Energy

Zong-Kuan Guo; Yun-Song Piao; Xinmin Zhang; Yuan-Zhong ZhangSubjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

We investigate in this paper the cosmological evolution of a dark energy model with two scalar fields where one of the scalar has canonical kinetic energy and another scalar has negative kinetic energy term. For such a system with exponential potentials we find that during the evolution of the universe the equation of state w changes from w > ?1 to w < ?1, which is consistent with the recent observations. A phase-plane analysis shows that the “phantom”-dominated scaling solution is the stable late-time attractor of this type of models. |

submitted time
2017-09-27
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Attractor Behavior of Phantom Cosmology

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

We investigate the cosmological attractor of the minimally coupled, self-interacting phantom field with a positive energy density but negative pressure. It is proved that the phantom cosmology is rigid in the sense that there exists a unique attractor solution. We plot the trajectories in the phase space numerically for the phantom field with three typical potentials. Phase portraits indicate that an initial kinetic term decays rapidly and the trajectories reach the unique attractor curve. We find that the curve corresponds to the slow-climb solution. |

Cosmological Scaling Solutions of Multiple Tachyon Fields with Inverse Square Potentials

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

We investigate cosmological dynamics of multiple tachyon fields with inverse square potentials.A phase-space analysis of the spatially flat FRW models shows that there exists power-law cosmological scaling solutions. We study the stability of the solutions and find that the potential-kinetic-scaling solution is a global attractor. However, in the presence of a barotropic fluid the solution is an attractor only in one region of the parameter space and the tracking solution is an attractor in the other region. We briefly discuss the physical consequences of these results. |

Cosmological Scaling Solutions and Multiple Exponential Potentials

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

We present a phase-space analysis of cosmology containing multiple scalar fields with positive and negative exponential potentials. We show that there exist power-law multi-kinetic potential scaling solutions for sufficiently flat positive potentials or steep negative potentials.The former is the unique late-time attractor and the well-known assisted inflationary solution, but the later is never unstable in an expanding universe. Moreover, for steep negative potentials there exist a kinetic-dominated regime in which each solution is a late-time attractor. We briefly discuss the physical consequences of these results. |

[1 Pages/ 6 Totals]