Density perturbations in general modified gravitational theories

Journal Article · Thu Jul 15 00:00:00 EDT 2010 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.82.023524· OSTI ID:21410106

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

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1. Department of Physics, Faculty of Science, Tokyo University of Science, 1-3, Kagurazaka, Shinjuku-ku, Tokyo 162-8601 (Japan)
2. Institute for the Physics and Mathematics of the Universe (IPMU), The University of Tokyo, Chiba 277-8582 (Japan)

We derive the equations of linear cosmological perturbations for the general Lagrangian density f(R,{phi},X)/2+L{sub c}, where R is a Ricci scalar, {phi} is a scalar field, and X=-{partial_derivative}{sup {mu}{phi}{partial_derivative}}{sub {mu}{phi}/}2 is a field kinetic energy. We take into account a nonlinear self-interaction term L{sub c}={xi}({phi}) {open_square}{phi}({partial_derivative}{sup {mu}{phi}{partial_derivative}}{sub {mu}{phi}}) recently studied in the context of ''Galileon'' cosmology, which keeps the field equations at second order. Taking into account a scalar-field mass explicitly, the equations of matter density perturbations and gravitational potentials are obtained under a quasistatic approximation on subhorizon scales. We also derive conditions for the avoidance of ghosts and Laplacian instabilities associated with propagation speeds. Our analysis includes most of modified gravity models of dark energy proposed in literature; and thus it is convenient to test the viability of such models from both theoretical and observational points of view.

• OSTI ID: 21410106
• Journal Information: Physical Review. D, Particles Fields, Vol. 82, Issue 2; Other Information: DOI: 10.1103/PhysRevD.82.023524; (c) 2010 The American Physical Society; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
APPROXIMATIONS
COSMOLOGICAL MODELS
COSMOLOGY
DENSITY
DISTURBANCES
FIELD EQUATIONS
GRAVITATION
INSTABILITY
INTERACTIONS
KINETIC ENERGY
LAGRANGIAN FUNCTION
LAPLACIAN
MASS
NONLINEAR PROBLEMS
NONLUMINOUS MATTER
PERTURBATION THEORY
SCALAR FIELDS
VELOCITY
CALCULATION METHODS
ENERGY
EQUATIONS
FUNCTIONS
MATHEMATICAL MODELS
MATHEMATICAL OPERATORS
MATTER
PHYSICAL PROPERTIES