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Second-order matter density perturbations and skewness in scalar-tensor modified gravity models
Takayuki Tatekawa, Shinji Tsujikawa
We study second-order cosmological perturbations in scalar-tensor models of dark energy that satisfy local gravity constraints, including f(R) gravity. We derive equations for matt…
Generic estimates for magnetic fields generated during inflation including Dirac-Born-Infeld theories
Kazuharu Bamba, Nobuyoshi Ohta, Shinji Tsujikawa
We estimate the strength of large-scale magnetic fields produced during inflation in the framework of Dirac-Born-Infeld (DBI) theories. This analysis is sufficiently general in the…
The effect of modified gravity on weak lensing
Shinji Tsujikawa, Takayuki Tatekawa
We study the effect of modified gravity on weak lensing in a class of scalar-tensor theory that includes gravity as a special case. These models are designed to satisfy loca…
Constraints on scalar-tensor models of dark energy from observational and local gravity tests
Shinji Tsujikawa, Kotub Uddin, Shuntaro Mizuno +2
We construct a family of viable scalar-tensor models of dark energy (DE) which possess a phase of late-time acceleration preceded by a standard matter era, while at the same time s…
Density perturbations in f(R) gravity theories in metric and Palatini formalisms
Shinji Tsujikawa, Kotub Uddin, Reza Tavakol
We make a detailed study of matter density perturbations in both metric and Palatini formalisms in theories whose Lagrangian density is a general function, f(R), of the Ricci scala…
Observational signatures of f(R) dark energy models that satisfy cosmological and local gravity constraints
Shinji Tsujikawa
We discuss observational consequences of f(R) dark energy scenarios that satisfy local gravity constraints (LGC) as well as conditions of the cosmological viability. The model we s…