Phantom Dark Energy Zong-Kuan Guo (advisor: Yuan-Zhong Zhang) Institute of Theoretical Physics, Chinese Academy of Sciences, P.O. Box 2735, Beijing 100080, P.R.China
Outline Observations Dark Energy Models Phantom Dark Energy Hybrid Dark Energy — Phantom and Quintessence Interacting Phantom Dark Energy Conclusions
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)
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/0106109 )
from astro-ph/0005111
Modified gravity models Holographic Dark Energy (hep-th/0403127) DGP Model (astro-ph/0105068) Cardassian Model (astro-ph/0201229) Chaplygin-gas Model (gr-qc/0103004)
Dynamical field dark energy Qintessence Model (astro-ph/9807002) K-essence Model (astro-ph/0004134) A Dynamical Approach Model (hep-th/0306108) Phantom Model (astro-ph/9908168)
from astro-ph/0311364
from astro-ph/0404062
Phantom Dark Energy Equation of motion: Equation of state:
Physical properties: Problems: 1. Attractor behavior 2. Equation of state parameter 3. Big rip (astro-ph/0302506 ) 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/0301273 )
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/0302506 )
Increasing energy density Matter (w=0) Radiation (w=1/3) Cosmological constant (w=-1) Qintessence (-1<w<0) Phantom (w<-1) Acceleration condition:
Energy condition Acceleration condition: violates the strong energy condition. Phantom energy density violates the weak energy condition.
Attractor behavior Hamilton-Jacobi equations: Suppose from astro-ph/0404225
Existence of attractor Uniqueness of attractor
Hybrid Dark Energy — Phantom and Quintessence from astro-ph/0410654
Interacting Phantom Dark Energy from astro-ph/0410654
Define Assume
Define from astro-ph/0412624
Conclusions Equation of state parameter Attractor behavior Coincidence problem → interacting phantom dark energy Big rip → hybrid phantom-quintessence dark energy
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