3 papers
gr-qc2025
Vacuum Magnetospheres around Kerr Black Holes with a Thin Disk
Yota Endo, Hideki Ishihara, Masaaki Takahashi
We construct a model for stationary and axisymmetric black hole magnetospheres by solving the vacuum Maxwell equations in Kerr backgrounds. The poloidal magnetic field is generated…
gr-qc2024
Spacetime constructed from a contact manifold with a degenerate metric
Hiroshi Kozaki, Hideki Ishihara, Tatsuhiko Koike +1
We construct a four-dimensional spacetime using a three-dimensional contact manifold equipped with a degenerate metric. The degenerate metric is set to be compatible with the conta…
hep-th2024
Gravastars as Nontopological Solitons
Tatsuya Ogawa, Hideki Ishihara
We investigate a coupled system consisting of a complex scalar field, a U(1) gauge field, a complex Higgs scalar field, and Einstein gravity. We present nontopological soliton star…