Screening of cosmological constant for De Sitter Universe in non-local gravity, phantom-divide crossing and finite-time future singularities
2012
42 pages
Published in:
- Gen.Rel.Grav. 44 (2012) 1321-1356
e-Print:
- 1104.2692 [hep-th]
Report number:
- YITP-11-46
View in:
Citations per year
Abstract: (arXiv)
We investigate de Sitter solutions in non-local gravity as well as in non-local gravity with Lagrange constraint multiplier. We examine a condition to avoid a ghost and discuss a screening scenario for a cosmological constant in de Sitter solutions. Furthermore, we explicitly demonstrate that three types of the finite-time future singularities can occur in non-local gravity and explore their properties. In addition, we evaluate the effective equation of state for the universe and show that the late-time accelerating universe may be effectively the quintessence, cosmological constant or phantom-like phases. In particular, it is found that there is a case in which a crossing of the phantom divide from the non-phantom (quintessence) phase to the phantom one can be realized when a finite-time future singularity occurs. Moreover, it is demonstrated that the addition of an term can cure the finite-time future singularities in non-local gravity. It is also suggested that in the framework of non-local gravity, adding an term leads to possible unification of the early-time inflation with the late-time cosmic acceleration.Note:
- 42 pages, no figure, version accepted for publication in General Relativity and Gravitation
- 04.50.Kd
- 95.36.+x
- 98.80.-k
- Modified theories of gravity
- Dark energy
- Cosmology
- gravitation: nonlocal
- expansion: acceleration
- cosmological constant: screening
- phantom: crossing
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