89 citations · 774 across the 55 of their papers we have counts for
37 papers · 1 filter
Gravitational-wave Echoes Beyond the Hubble Time from Quantum Black Holes
Che-Yu Chen, Naritaka Oshita, Yuki Yokokura
We investigate gravitational-wave echoes in a horizonless compact object model, a non-perturbative solution of the semi-classical Einstein equation that reproduces the entropy-area…
Theoretical Aspects of Direct Waves in Kerr Black Holes: Pole-Splitting Method for Ringdown Analysis
Nao Nakamoto, Naritaka Oshita, Hiroki Takeda
We formulate the theoretical aspects of direct waves (DWs) in the case of extreme-mass merger. A DW is a source-driven waveform characterized by a complex frequency , wh…
Excitation factors and exceptional points of Kerr-de Sitter quasinormal modes
Dario Rossi, Naritaka Oshita, Leonardo Gualtieri +1
We compute the excitation factors of Kerr-de Sitter black hole quasinormal modes using two different techniques: a Heun function representation and an expansion of the solution in…
Excitation region of Kerr black hole quasinormal modes from Stokes geometry
Naritaka Oshita
We investigate the excitation region of black hole quasinormal modes (QNMs) from both analytical and numerical perspectives. On the analytical side, we propose that the QNM excitat…
Detectability of avoided crossings in black hole ringdowns
Hayato Imafuku, Naritaka Oshita, Hiroki Takeda
Quasinormal modes (QNMs) of black holes can exhibit avoided crossings (ACs), in which specific QNM frequencies approach each other while their amplitudes are enhanced and acquire n…
Exceptional Lines and Excitation of (Nearly) Double-Pole Quasinormal Modes: A Semi-Analytic Study in the Nariai Black Hole
Nao Nakamoto, Naritaka Oshita
We show that quasinormal modes (QNMs) of a massive scalar field in Kerr-de Sitter and Myers-Perry black holes exhibit an exceptional line (EL), which is a continuous set of excepti…
Spectral instability of parametrized black hole quasinormal modes in the high-overtone limit via the exact WKB analysis
Taiga Miyachi, Ryo Namba, Hidetoshi Omiya +1
We study the asymptotic behavior of parametrized black hole quasinormal modes (QNMs) in the high-overtone limit. To gain insights into their analytical structure, we apply the exac…
Dynamical Tidal Response of Non-rotating Black Holes: Connecting the MST Formalism and Worldline EFT
Hajime Kobayashi, Shinji Mukohyama, Naritaka Oshita +2
The response of a black hole (BH) to tidal forces encodes key information about the underlying gravitational theory and affects the waveform of gravitational waves emitted during b…
Probing Direct Waves in Black Hole Ringdowns
Naritaka Oshita, Sizheng Ma, Yanbei Chen +1
Merger gravitational waves from binary black hole coalescence carry rich information about the underlying spacetime dynamics. We analyze merger waves from comparable-mass and extre…
Black hole spectroscopy: from theory to experiment
Emanuele Berti, Vitor Cardoso, Gregorio Carullo +65
The "ringdown" radiation emitted by oscillating black holes has great scientific potential. By carefully predicting the frequencies and amplitudes of black hole quasinormal modes a…
Parametrized Tidal Dissipation Numbers of Non-rotating Black Holes
Hajime Kobayashi, Shinji Mukohyama, Naritaka Oshita +2
A set of tidal dissipation numbers (TDNs) quantifies the absorption of the tidal force exerted by a companion during an inspiralling phase of a binary compact object. This tidal di…
Quasinormal Modes from EFT of Black Hole Perturbations in Vector-Tensor Gravity
Shogo Tomizuka, Hajime Kobayashi, Naritaka Oshita +2
We study the dynamics of odd-parity perturbations on a static and spherically symmetric black hole background with a timelike vector field based on the effective field theory (EFT)…
Overtones and Nonlinearities in Binary Black Hole Ringdowns
Matthew Giesler, Sizheng Ma, Keefe Mitman +11
Using high-accuracy numerical relativity waveforms, we confirm the presence of numerous overtones of the , quasinormal mode early in the ringdown of binary black hole…
Reconstruction of ringdown with excitation factors
Naritaka Oshita, Vitor Cardoso
In black hole perturbation formalism, the gravitational waveform is obtained by the convolution of the Green's function and the source term causing radiation emission. Hence, the r…
(In)stability of the black hole greybody factors and ringdowns against a small-bump correction
Naritaka Oshita, Kazufumi Takahashi, Shinji Mukohyama
Recently, it has been proposed that the black hole greybody factors can be important to model ringdown spectral amplitudes. We study the stability of greybody factors against a sma…
Scalar Quasi-Normal Modes of a Loop Quantum Black Hole
Etera R. Livine, Clara Montagnon, Naritaka Oshita +1
We compute the Quasi-Normal Mode (QNM) frequencies for scalar perturbations for modified Schwarzschild black holes in Loop Quantum Gravity. We study the singularity-free polymerize…
Tidal Love Numbers from EFT of Black Hole Perturbations with Timelike Scalar Profile
Chams Gharib Ali Barura, Hajime Kobayashi, Shinji Mukohyama +3
We study static tidal Love numbers (TLNs) of a static and spherically symmetric black hole for odd-parity metric perturbations. We describe black hole perturbations using the effec…
Black holes, multiple propagation speeds, and energy extraction
Vitor Cardoso, Shinji Mukohyama, Naritaka Oshita +1
The Standard Model of particle physics predicts the speed of light to be a universal speed of propagation of massless carriers. However, other possibilities exist -- including Lore…
Slowly decaying ringdown of a rapidly spinning black hole II: Inferring the masses and spins of supermassive black holes with LISA
Daiki Watarai, Naritaka Oshita, Daichi Tsuna
Electromagnetic observations reveal that almost all galaxies have supermassive black holes (SMBHs) at their centers, but their properties, especially their spins, are not fully und…
Greybody Factors Imprinted on Black Hole Ringdowns. II. Merging Binary Black Holes
Kazumasa Okabayashi, Naritaka Oshita
The spectral amplitude of the merger-ringdown gravitational wave (GW) emitted by a comparable mass-ratio black hole merger is modeled by the greybody factor of the remnant black ho…
Greybody Factors Imprinted on Black Hole Ringdowns: an alternative to superposed quasi-normal modes
Naritaka Oshita
It is shown that the spectral amplitude of gravitational-wave (GW) ringdown of a Kerr black hole sourced by an extreme mass ratio merger can be modeled by the $\textit{greybody fac…
Slowly Decaying Ringdown of a Rapidly Spinning Black Hole: Probing the No-Hair Theorem by Small Mass-Ratio Mergers with LISA
Naritaka Oshita, Daichi Tsuna
The measurability of multiple quasinormal (QN) modes, including overtones and higher harmonics, with the Laser Interferometer Space Antenna is investigated by computing the gravita…
Thermal Ringdown of a Kerr Black Hole: Overtone Excitation, Fermi-Dirac Statistics and Greybody Factor
Naritaka Oshita
We find a significant destructive interference among Kerr overtones in the early ringdown induced by an extreme mass-ratio merger of a massive black hole and a compact object, and…
Evaporation of Echoing Black Holes
Naritaka Oshita, Hayato Motohashi, Sousuke Noda
We compute the graybody factor and evaporation rate of a rotating black hole in the presence of a hypothetical reflective surface slightly outside the outer horizon radius, assumin…