1. Phantom Dark Energy Zong-Kuan Guo (advisor: Yuan-Zhong Zhang)
Institute of Theoretical Physics, Chinese Academy of Sciences,
P.O. Box 2735, Beijing , P.R.China

2. Outline Observations Dark Energy Models Phantom Dark Energy
Hybrid Dark Energy
— Phantom and Quintessence
Interacting Phantom Dark Energy
Conclusions

3. Observations WMAP(2003) Type Ia Supernovae
1. the High-Z Supernova Team (Riess et al. 1998)
2. the Supernova Cosmology Project (Perlmutter et al. 1999)

4. Dark energy models Cosmological Constant 1. the fine-tuning problem
2. the coincidence problem
3. the equation of state
4. an asymptotically de Sitter spacetime
( hep-th/ )

5. from astro-ph/

6. Modified gravity models
Holographic Dark Energy (hep-th/ )
DGP Model (astro-ph/ )
Cardassian Model
(astro-ph/ )
Chaplygin-gas Model (gr-qc/ )

7. Dynamical field dark energy
Qintessence Model (astro-ph/ )
K-essence Model (astro-ph/ )
A Dynamical Approach Model (hep-th/ )
Phantom Model (astro-ph/ )

8. from astro-ph/

9. from astro-ph/

10. Phantom Dark Energy
Equation of motion:
Equation of state:

11. Physical properties: Problems: 1. Attractor behavior
2. Equation of state parameter
3. Big rip (astro-ph/ )
4. Increasing energy density with the expansion of the universe
Problems:
1. Coincidence problem
2. Violation of the weak energy condition
3. Stability Problem (astro-ph/ )

12. Big rip
The phantom energy rips apart the Milky Way, solar system, Earth, and ultimately the molecules, atoms, nuclei, and nucleons of which we are composed, before the death of the Universe in a ''Big Rip''. (from astro-ph/ )

13. Increasing energy density
Matter (w=0)
Radiation (w=1/3)
Cosmological constant (w=-1)
Qintessence (-1<w<0)
Phantom (w<-1)
Acceleration condition:

14. Energy condition Acceleration condition:
violates the strong energy condition.
Phantom energy density
violates the weak energy condition.

15. Attractor behavior Hamilton-Jacobi equations: Suppose
from astro-ph/

16. Existence of attractor
Uniqueness of attractor

20. Hybrid Dark Energy — Phantom and Quintessence
from astro-ph/

24. Interacting Phantom Dark Energy
from astro-ph/

25. Define
Assume

29. Define
from astro-ph/

30. Conclusions Equation of state parameter Attractor behavior
Coincidence problem → interacting phantom dark energy
Big rip → hybrid phantom-quintessence dark energy

31. Thanks for your attendance!