Kyushu University Academic Staff Educational and Research Activities Database
List of Papers
Kazuhiro Yamamoto Last modified date:2020.06.19

Professor / Department of Physics / Faculty of Sciences


Papers
1. Yue Nan, Kazuhiro Yamamoto, Hajime Aoki, Satoshi Iso, and Daisuke Yamauchi, Large-scale inhomogeneity of dark energy produced in the ancestor vacuum, PHYSICAL REVIEW D, 10.1103/PhysRevD.99.103512, 99, 10, 2019.05, We investigate large-scale inhomogeneity of dark energy in the bubble nucleation scenario of the universe. In this scenario, the present universe was created by a bubble nucleation due to quantum tunneling from a metastable ancestor vacuum, followed by a primordial inflationary era. During the bubble nucleation, supercurvature modes of some kind of a scalar field are produced, and remain until present without decaying; thus they can play a role of the dark energy, if the mass of the scalar field is sufficiently light in the present universe. The supercurvature modes fluctuate at a very large spatial scale, much longer than the Hubble length in the present universe. Thus they create large-scale inhomogeneities of the dark energy, and generate large-scale anisotropies in the cosmic microwave background (CMB) fluctuations. This is a notable feature of this scenario, where quantum fluctuations of a scalar field are responsible for the dark energy. In this paper, we calculate imprints of the scenario on the CMB anisotropies through the integrated Sachs-Wolfe (ISW) effect, and give observational constraints on the curvature parameter ΩK and on an additional parameter ε describing some properties of the ancestor vacuum..
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