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Can higher curvature corrections cure the singularity problem in f(R) gravity?
Tsutomu Kobayashi, Kei-ichi Maeda
Although modified gravity models can be made to satisfy solar system and cosmological constraints, it has been shown that they have the serious drawback of the nonexistence…
Relativistic stars in f(R) gravity, and absence thereof
Tsutomu Kobayashi, Kei-ichi Maeda
Several f(R) modified gravity models have been proposed which realize the correct cosmological evolution and satisfy solar system and laboratory tests. Although nonrelativistic ste…
Primordial magnetic fields from second-order cosmological perturbations: Tight coupling approximation
Satoshi Maeda, Satoshi Kitagawa, Tsutomu Kobayashi +1
We explore the possibility of generating large-scale magnetic fields from second-order cosmological perturbations during the pre-recombination era. The key process for this is Thom…
Cosmological magnetic fields from nonlinear effects
Tsutomu Kobayashi, Roy Maartens, Tetsuya Shiromizu +1
In the standard cosmological model, magnetic fields and vorticity are generated during the radiation era via second-order density perturbations. In order to clarify the complicated…