20 citations · 33 across the 4 of their papers we have counts for
9 papers
Odd-parity ringdown gravitational waves of a spherically symmetric black hole with perfect fluid accretion
Rikuto Ohashi, Yasutaka Koga, Hiroyuki Nakano +2
The ringdown waves from a black hole offer a clean probe of strong-field gravity, but a matter distribution that may be present around a realistic black hole renders the background…
Urban Reconstruction and Population Redistribution: Evidence from Tokyo after the Great Kanto Earthquake
Kota Ogasawara
This study examines the impact of the 1923 Great Kanto Earthquake on population distribution within Tokyo City. The earthquake triggered massive fires that devastated nearly half o…
Photon emission from inside the innermost stable circular orbit
Takahisa Igata, Kazunori Kohri, Kota Ogasawara
We consider a situation where a light source orbiting the innermost stable circular orbit (ISCO) of the Kerr black hole is gently falling from the marginally stable orbit due to an…
Complete classification of photon escape in the Kerr black hole spacetime
Kota Ogasawara, Takahisa Igata
We consider necessary and sufficient conditions for photons emitted from the vicinity of a Kerr black hole horizon to escape to infinity. The radial equation of motion determines n…
Escape probability of a photon emitted near the black hole horizon
Kota Ogasawara, Takahisa Igata, Tomohiro Harada +1
We investigate the escape of photons from the vicinity of the horizon to infinity in the Kerr-Newmann black hole spacetime. We assume that a light source is at rest in a locally no…
Observability of the innermost stable circular orbit in a near-extremal Kerr black hole
Takahisa Igata, Keisuke Nakashi, Kota Ogasawara
We consider the escape probability of a photon emitted from the innermost stable circular orbit (ISCO) of a rapidly rotating black hole. As an isotropically emitting light source o…