6 papers
Dyonic hairy black holes in gauge-invariant scalar-vector-tensor theories: Cubic and quartic SVT sectors
Masaki Kitagawa, Naoki Tsukamoto, Ryotaro Kase
We construct and classify asymptotically flat, static, and spherically symmetric hairy black hole solutions in gauge-invariant scalar-vector-tensor (SVT) theories carrying b…
Gravitational lensing inside and outside of a marginally unstable photon sphere in a general, static, spherically symmetric, and asymptotically-flat spacetime in strong deflection limits
Naoki Tsukamoto
It is believed that rays bent inside and outside photon spheres could affect partially the black hole shadow images by the Event Horizon Telescope and the rays near photon spheres…
Linear perturbations of dyonic black holes in the lowest-order gauge-invariant scalar-vector-tensor theories
Kitaro Taniguchi, Shunta Nishimura, Naoki Tsukamoto +1
We study linear perturbations on top of the static and spherically symmetric background of dyonic black hole solutions endowed with electric and magnetic charges, as well as a scal…
Neutral particle collisions near Gibbons-Maeda-Garfinkle-Horowitz-Strominger black holes after shadow observations
Naoki Tsukamoto, Ryotaro Kase
A Gibbons-Maeda-Garfinkle-Horowitz-Strominger (GMGHS) black hole with a magnetic charge (or an electric charge) has noteworthy features that its scalar curvature near the event hor…
Constraints on the black-hole charges of M87* and Sagittarius A* by changing rates of photon spheres can be relaxed
Naoki Tsukamoto, Ryotaro Kase
The Event Horizon Telescope (EHT) Collaboration observed ring images called the shadows of M87* and Sagittarius~A* (Sgr~A*), which are supermassive objects in M87 and our galaxy, r…
Circular light orbits of a general, static, and spherical symmetrical wormhole with symmetry
Naoki Tsukamoto
Recently, the ring images or the shadow images of the centers of the galaxy M87 and the Milky way have been reported by Event Horizon Telescope Collaboration. It is believed that t…