The Vector Mode in the Second-order Cosmological Perturbation Theory

Description

This thesis sheds valuable new light on the second-order cosmological perturbation theory, extensively discussing it in the context of cosmic microwave background (CMB) fluctuations. It explores the observational consequences of the second-order vector mode, and addresses magnetic field generation and the weak lensing signatures, which are key phenomena of the vector mode. The author demonstrates that the second-order vector mode, which never appears at the linear-order level, naturally arises from the non-linear coupling of the first-order scalar modes. This leads to the remarkable statement that the vector-order mode clearly contributes to the generation of cosmological magnetic fields. Moreover, the weak lensing observations are shown to be accessible to the vector mode. On the basis of ongoing and forthcoming observations, the thesis concludes that the second-order vector mode is detectable. Front Matter ....Pages i-xiii Introduction (Shohei Saga)....Pages 1-13 Basics of Cosmological Perturbation Theory (Shohei Saga)....Pages 15-51 Generation of Magnetic Fields (Shohei Saga)....Pages 53-73 Weak Lensing (Shohei Saga)....Pages 75-106 21 cm Lensing in the Dark Ages (Shohei Saga)....Pages 107-128 Summary of This Thesis (Shohei Saga)....Pages 129-131 Back Matter ....Pages 133-136