Conditions for the cosmological viability of the most general scalar-tensor theories and their applications to extended Galileon dark energy models

Journal Article · Wed Feb 01 04:00:00 EST 2012 · Journal of Cosmology and Astroparticle Physics

DOI:https://doi.org/10.1088/1475-7516/2012/02/007· OSTI ID:22279742

Felice, Antonio De ^[1]; Tsujikawa, Shinji ^[2]

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1. TPTP and NEP, The Institute for Fundamental Study, Naresuan University, Phitsanulok 65000 (Thailand)
2. Department of Physics, Faculty of Science, Tokyo University of Science, 1-3, Kagurazaka, Shinjuku-ku, Tokyo 162-8601 (Japan)

In the Horndeski's most general scalar-tensor theories with second-order field equations, we derive the conditions for the avoidance of ghosts and Laplacian instabilities associated with scalar, tensor, and vector perturbations in the presence of two perfect fluids on the flat Friedmann-Lemaître-Robertson-Walker (FLRW) background. Our general results are useful for the construction of theoretically consistent models of dark energy. We apply our formulas to extended Galileon models in which a tracker solution with an equation of state smaller than -1 is present. We clarify the allowed parameter space in which the ghosts and Laplacian instabilities are absent and we numerically confirm that such models are indeed cosmologically viable.

• OSTI ID: 22279742
• Journal Information: Journal of Cosmology and Astroparticle Physics, Journal Name: Journal of Cosmology and Astroparticle Physics Journal Issue: 02 Vol. 2012; ISSN 1475-7516
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
COSMOLOGICAL MODELS
COSMOLOGY
DISTURBANCES
EQUATIONS OF STATE
FIELD EQUATIONS
LAPLACIAN
MATHEMATICAL SOLUTIONS
NONLUMINOUS MATTER
SCALARS
SPACE
VECTORS