11 papers
Probing higher curvature gravity via ringdown with overtones
Keisuke Nakashi, Masashi Kimura, Hayato Motohashi +1
We investigate metric perturbations of a spherically symmetric black hole in higher curvature gravity. We show that higher curvature corrections deform the near-horizon region of t…
Inverting no-hair theorems: How requiring General Relativity solutions restricts scalar-tensor theories
Hajime Kobayashi, Shinji Mukohyama, Johannes Noller +3
Black hole solutions in general scalar-tensor theories are known to permit hair, i.e. non-trivial scalar profiles and/or metric solutions different from the ones of General Relativ…
EFT of Dark Energy with Cosmic Chronometers: Reconstructing Background EFT Functions
Fumiya Okamatsu, Kazufumi Takahashi
The effective field theory (EFT) of dark energy provides a model-independent framework for studying cosmology within scalar-tensor theories. In this work, we explore how the time e…
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…
Scalar quasinormal modes of rotating black holes in parity-violating gravity
Hiroaki W. H. Tahara, Hayato Motohashi, Kazufumi Takahashi +1
Recently, an exact rotating black hole solution in a parity-violating theory of gravity was obtained via a conformal transformation of the Kerr solution in general relativity, with…
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)…