50 citations · 541 across the 47 of their papers we have counts for
47 papers
General relativistic effects on photon spectrum emitted from dark matter halos around primordial black holes
Toya Suzuki, Takahisa Igata, Kazunori Kohri +1
We investigate general relativistic effects on the photon spectrum emitted from decaying (or annihilating) particle dark matter in the halo surrounding a primordial black hole. The…
Extended mass and spheroidal deformation effects on epicyclic frequencies and periapsis shift in quasi-circular orbits
Takahisa Igata
We investigate the effects of extended mass and spheroidal deformation on the periapsis shift of quasi-circular orbits inside a gravitating mass distribution in the Newtonian frame…
Gravitational lensing and accretion disk imaging of a Buchdahl dense core
Takahisa Igata, Motoki Omamiuda, Yohsuke Takamori
In this paper, we investigate the gravitational lensing and accretion disk imaging characteristics of a dense core modeled by the Buchdahl spacetime. By imposing the appropriate en…
General formulae for the periapsis shift of a quasi-circular orbit in static spherically symmetric spacetimes and the active gravitational mass density
Tomohiro Harada, Takahisa Igata, Hiromi Saida +1
We study the periapsis shift of a quasi-circular orbit in general static spherically symmetric spacetimes. We derive two formulae in full order with respect to the gravitational fi…
Periapsis shifts in dark matter distribution with a dense core
Takahisa Igata, Yohsuke Takamori
We consider the periapsis shifts in dark matter distribution with a dense core. We model the dark matter distribution as an isotropic gas sphere, the Emden polytropic sphere of ind…
Periapsis shifts in dark matter distribution around a black hole
Takahisa Igata, Tomohiro Harada, Hiromi Saida +1
We consider the periapsis shifts of bound orbits of stars on static clouds around a black hole. The background spacetime is constructed from a Schwarzschild black hole surrounded b…