23 citations · 33 across the 4 of their papers we have counts for
4 papers
Shadow formation in gravitational collapse: Redshift and blueshift by spacetime dynamics
Yasutaka Koga, Nobuyuki Asaka, Masashi Kimura +1
A black hole illuminated by a background light source is observed as a black hole shadow. For a black hole formed by gravitational collapse of a transmissive object, redshift of li…
Parametrized Black Hole Quasinormal Ringdown Formalism for Higher Overtones
Shin'ichi Hirano, Masashi Kimura, Masahide Yamaguchi +1
We investigate the parametrized black hole quasinormal ringdown formalism, which is a robust framework used to analyze quasinormal modes in systems that closely resemble general re…
Gravitational mode mixing around black holes in scalar-tensor theories with parity-violating terms
Shin'ichi Hirano, Masashi Kimura, Masahide Yamaguchi
We investigate black holes and gravitational perturbations when both the scalar Gauss-Bonnet and dynamical Chern-Simons gravity sectors coexist in addition to the Einstein-Hilbert…
Black hole ringdown from physically sensible initial value problem in higher-order scalar-tensor theories
Keisuke Nakashi, Masashi Kimura, Hayato Motohashi +1
We study odd-parity perturbations about static and spherically symmetric black hole solutions with a linearly time-dependent scalar field in higher-order scalar-tensor theories. In…