161 citations · 197 across the 2 of their papers we have counts for
6 papers
Negative time delay of light by a gravitational concave lens
Koki Nakajima, Koji Izumi, Hideki Asada
Gravitational lens models, some of which might act as if a concave lens, have been recently investigated by using a static and spherically symmetric modified spacetime metric that…
Gravitational lensing in Tangherlini spacetime in the weak gravitational field and the strong gravitational field
Naoki Tsukamoto, Takao Kitamura, Koki Nakajima +1
The gravitational lensing effects in the weak gravitational field by exotic lenses have been investigated intensively to find nonluminous exotic objects. Gravitational lensing base…
Microlensed image centroid motions by an exotic lens object with negative convergence or negative mass
Takao Kitamura, Koji Izumi, Koki Nakajima +2
Gravitational lens models with negative convergence inspired by modified gravity theories, exotic matter and energy have been recently examined, in such a way that a static and sph…
Gravitational lensing shear by an exotic lens object with negative convergence or negative mass
Koji Izumi, Chisaki Hagiwara, Koki Nakajima +2
Gravitational lens models with negative convergence(surface mass density projected onto the lens plane) inspired by modified gravity theories, exotic matter and energy have been re…
Demagnifying gravitational lenses toward hunting a clue of exotic matter and energy
Takao Kitamura, Koki Nakajima, Hideki Asada
We examine a gravitational lens model inspired by modified gravity theories and exotic matter and energy. We study an asymptotically flat, static, and spherically symmetric spaceti…
Deflection angle of light in an Ellis wormhole geometry
Koki Nakajima, Hideki Asada
We reexamine the light deflection by an Ellis wormhole. The bending angle as a function of the ratio between the impact parameter and the throat radius of the wormhole is obtained…