Zobrazeno 1 - 10
of 20
pro vyhledávání: '"Okabayashi, Kazumasa"'
We examine the vacuum state and its corresponding renormalized stress-energy tensor (RSET) in static horizonless regular spacetime in both two- and four-dimensions. Using the local field formulation of the anomaly-induced effective action, we show th
Externí odkaz:
http://arxiv.org/abs/2411.12617
Autor:
Okabayashi, Kazumasa, Oshita, Naritaka
Publikováno v:
Phys. Rev. D 110, 064086 (2024)
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 hole. We also include the post-Newtonian correction to the greybody fact
Externí odkaz:
http://arxiv.org/abs/2403.17487
Publikováno v:
Phys.Rev.D 110 (2024) 8, 083508
We revisit the path-integral approach to the wave function of the Universe by utilizing Lefschetz thimble analyses and resurgence theory. The traditional Euclidean path-integral of gravity has the notorious ambiguity of the direction of Wick rotation
Externí odkaz:
http://arxiv.org/abs/2402.09981
Radiative gravastar with thermal spectrum; Sudden vacuum condensation without gravitational collapse
The gravastar is an exotic compact object proposed as a final product of gravitational collapse of a massive object in order to resolve problems associated with black holes. It is enclosed by a thin crust and the inside of it is occupied by the posit
Externí odkaz:
http://arxiv.org/abs/2211.13477
We study the quantum particle creation in a toy model of spherically symmetric gravitational collapse whose final product is not a black hole but a gravastar. Precedent studies revealed that even in the case of the gravitational collapse to form a ho
Externí odkaz:
http://arxiv.org/abs/2203.14519
Publikováno v:
Phys. Rev. D 105, 104040 (2022)
A photon sphere is known as the geometrical structure shaping a black hole shadow. The mechanism is well understood for static or stationary black hole spacetimes such as the Schwarzschild and the Kerr spacetimes. In this paper, we investigate and ex
Externí odkaz:
http://arxiv.org/abs/2202.00201
Publikováno v:
Progress of Theoretical and Experimental Physics, Volume 2022, Issue 2, February 2022, 023E02
Hawking has predicted that the formation of a black hole by gravitational collapse causes quantum particle creation and the spectrum of the particles is almost thermal. This phenomenon is called the Hawking radiation. Recently, it has been predicted
Externí odkaz:
http://arxiv.org/abs/2107.05260
Publikováno v:
Phys. Rev. D 102, 044011 (2020)
The so-called black hole shadow is not a silhouette of a black hole but an image of a collapsing object or a white hole. Hence it is non-trivial whether black hole shadows merge with each other when black holes coalesce with each other. In this paper
Externí odkaz:
http://arxiv.org/abs/2003.07519
Autor:
Okabayashi, Kazumasa, Maeda, Kei-ichi
Publikováno v:
Progress of Theoretical and Experimental Physics, Volume 2020, Issue 1, January 2020, 013E01
We analyze the collisional Penrose process between a particle on the ISCO orbit around an extreme Kerr black hole and a particle impinging from infinity. We consider both cases with non-spinning and spinning particles. We evaluate the maximal efficie
Externí odkaz:
http://arxiv.org/abs/1907.07126
Publikováno v:
Phys. Rev. D 98, 064027 (2018)
We analyze collisional Penrose process of spinning test particles in an extreme Kerr black hole. We consider that two particles plunge into the black hole from infinity and collide near the black hole. For the collision of two massive particles, if t
Externí odkaz:
http://arxiv.org/abs/1804.07264