Zobrazeno 1 - 10
of 107
pro vyhledávání: '"Naruko, Atsushi"'
We consider axion cloud decay due to the axion-photon conversion with multi-pole background magnetic fields. We focus on the $\ell=m=1$ and $n=2$ mode for the axion field configuration since it has the largest growth rate associated with superradiant
Externí odkaz:
http://arxiv.org/abs/2312.07058
Publikováno v:
Phys. Rev. D 107, 043511 (2023)
In minisuperspace quantum cosmology, the Lorentzian path integral formulations of the no-boundary and tunneling proposals have recently been analyzed. But it has been pointed out that the wave function of linearized perturbations around a homogeneous
Externí odkaz:
http://arxiv.org/abs/2211.05306
Publikováno v:
PTEP 2023 (2023) 5, 053E02
A metric transformation is a tool to find a new theory of gravity beyond general relativity. The gravity action is guaranteed to be free from a dangerous Ostrogradsky mode as long as the metric transformation is regular and invertible. Various degene
Externí odkaz:
http://arxiv.org/abs/2209.02252
Publikováno v:
Physics Letters B 833 (2022) 137340
In quantum cosmology the DeWitt boundary condition is a proposal to set the wave function of the universe to vanish at the classical big-bang singularity. In this Letter, we show that in many gravitational theories including general relativity, the D
Externí odkaz:
http://arxiv.org/abs/2111.00665
Autor:
Takamori, Yohsuke, Naruko, Atsushi, Sakurai, Yusuke, Takahashi, Keitaro, Yamauchi, Daisuke, Yoo, Chul-Moon
A disformal Kerr black hole solution is a rotating black hole solution in a modified gravity theory which breaks the circular condition of spacetime differently from the case of the Kerr spacetime. In this paper, assuming that Sagittarius A* (Sgr A*)
Externí odkaz:
http://arxiv.org/abs/2108.13026
Publikováno v:
PTEP 2021 (2021) 9, 093E03
We study the metric backreaction of mass and angular momentum accretion on black holes. We first develop the formalism of monopole and dipole linear gravitational perturbations around the Schwarzschild black holes in the Eddington-Finkelstein coordin
Externí odkaz:
http://arxiv.org/abs/2105.05581
Autor:
Yoo, Chul-Moon, Naruko, Atsushi, Sakurai, Yusuke, Takahashi, Keitaro, Takamori, Yohsuke, Yamauchi, Daisuke
We consider an axion cloud around a black hole with background magnetic fields. We calculate the decay rate of the axion cloud due to the axion-photon conversion associated with the axion-photon coupling. For simplicity, we consider the situation whe
Externí odkaz:
http://arxiv.org/abs/2103.13227
We develop a systematic and unified approach to estimate all possible secondary (i.e. non-primordial) nonlinear effects to the cosmic microwave background (CMB) polarization, named curve-of-sight integration approach. In this approach, the Boltzmann
Externí odkaz:
http://arxiv.org/abs/2103.10639
Publikováno v:
Phys. Rev. D 104, 044021 (2021)
We investigate a Lorentz invariant action which is quadratic in two rank-2 symmetric tensor fields in Minkowski spacetime. We apply a scalar-vector-tensor decomposition to two tensor fields by virtue of 3-dimensional rotation-invariance of Minkowski
Externí odkaz:
http://arxiv.org/abs/2012.13461
In the wake of interest to find black hole solutions with scalar hair, we investigate the effects of disformal transformations on static spherically symmetric space-times with a non-trivial scalar field. In particular, we study solutions that have a
Externí odkaz:
http://arxiv.org/abs/1912.02845