109 citations · 1.6k across the 84 of their papers we have counts for
85 papers
Geometric deformations of symmetric spacetimes with a string cloud
Hiroshi Kozaki, Satsuki Matsuno, Tatsuhiko Koike +2
We establish a deformation framework for highly symmetric solutions to the Einstein equations. In this framework, four-dimensional metrics are constructed from three-dimensional η-…
Collective Excitations of Self-Gravitating Bose-Einstein Condensates: Breathing Mode and Appearance of Anisotropy under Self-Gravity
Kenta Asakawa, Hideki Ishihara, Makoto Tsubota
We investigate the collective mode of a self-gravitating Bose-Einstein condensate (BEC) described by the Gross-Pitaevskii-Poisson (GPP) equations. The self-gravitating BEC has garn…
Solitonic Gravastars in a U(1) gauge Higgs model
Tatsuya Ogawa, Hideki Ishihara
We numerically obtain gravastar solutions as nontopological solitons in a system that consists of a U(1) gauge Higgs model with a complex scalar field and Einstein gravity. The sol…
Nambu-Goto Strings with a null symmetry and contact structure
Hiroshi Kozaki, Tatsuhiko Koike, Yoshiyuki Morisawa +1
We study the classical dynamics of the Nambu-Goto strings with a null symmetry in curved spacetimes admitting a null Killing vector field. The Nambu-Goto equation is reduced to fir…
Relativistic Nontopological Soliton Stars in a U(1) Gauge Higgs Model
Yota Endo, Hideki Ishihara, Tatsuya Ogawa
We study spherically symmetric nontopological soliton stars (NTS stars) numerically in the coupled system of a complex scalar field, a U(1) gauge field, a complex Higgs scalar fiel…
Inhomogeneous Generalization of Einstein's Static Universe with Sasakian Space
Hideki Ishihara, Satsuki Matsuno
We construct exact static inhomogeneous solutions to Einstein's equations with counter flow of particle fluid and a positive cosmological constant by using the Sasaki metrics on th…