Kouji Ogawa

Perturbations of Spacetime around a Stationary Rotating Cosmic String (2008)

Ogawa, Kouji, Ishihara, Hideki, Kozaki, Hiroshi, Nakano, Hiroyuki

We consider the metric perturbations around a stationary rotating Nambu-Goto string in Minkowski spacetime. By solving the linearized Einstein equations, we study the effects of azimuthal...

Stationary Rotating Strings as Relativistic Particle Mechanics (2008)

Ogawa, Kouji, Ishihara, Hideki, Kozaki, Hiroshi, Nakano, Hiroyuki, Saito, Shinya

Stationary rotating strings can be viewed as geodesic motions in appropriate metrics on a two-dimensional space. We obtain all solutions describing stationary rotating strings in flat spacetime as an...

Quasinormal Ringing for Acoustic Black Holes at Low Temperature (2004)

Nakano, Hiroyuki, Kurita, Yasunari, Ogawa, Kouji, Yoo, Chul-Moon

We investigate a condensed matter ``black hole'' analogue, taking the Gross-Pitaevskii (GP) equation as a starting point. The linearized GP equation corresponds to a wave equation on a black hole...