Kengo Maeda
Current Organizations / Institutes
The organizations/institutes from the scholar's latest article
Research Subjects
Kengo Maeda has a total of 3 co-authors. Here are the top co-authors by number of shared publications:
- Makoto Narita
Department of Physics, Rikkyo University, Toshima-ku, Tokyo 171-8501, Japan
2 shared publications - Takashi Torii
Research Center for the Early Universe, University of Tokyo, Hongo, Bunkyo, Tokyo 113-0033, Japan
1 shared publication - Takashi Torii
Department of Physics Tokyo Institute of Technology Oh-Okayama Meguro-ku 152 Tokyo Japan
1 shared publication
Latest Publications
- 23 July 2001
- Published by American Physical Society (APS) in Physical Review D
- Vol. 64 (4) , 044007
Scalar hair on the black hole in asymptotically anti–de Sitter spacetime
We examine the no-hair conjecture in asymptotically anti–de Sitter (AdS) spacetime. First, we consider a real scalar field as the matter field and assume static spherically symmetric spacetime. Analysis of the asymptotics shows that the scalar field must approach the extremum of its potential. Using this fact, it is proved that there is no regular black hole solution when the scalar field is massless or has a “convex” potential. Surprisingly, while the scalar field has a growing mode around the local minimum of the potential, there is no growing mode around the local maximum. This implies that the local maximum is a kind of “attractor” of the asymptotic scalar field. We give two examples of the new black hole solutions with a nontrivial scalar field configuration numerically in the symmetric or asymmetric double well potential models. We study the stability of these solutions by using the linear perturbation method in order to examine whether or not the scalar hair is physical. In the symmetric double well potential model, we find that the potential function of the perturbation equation is positive semidefinite in some wide parameter range and that the new solution is stable. This implies that the black hole no-hair conjecture is violated in asymptotically AdS spacetime.
- 23 July 2001
- Published by American Physical Society (APS) in Physical Review D
- Vol. 64 (4) , 044007
Scalar hair on the black hole in asymptotically anti–de Sitter spacetime
We examine the no-hair conjecture in asymptotically anti–de Sitter (AdS) spacetime. First, we consider a real scalar field as the matter field and assume static spherically symmetric spacetime. Analysis of the asymptotics shows that the scalar field must approach the extremum of its potential. Using this fact, it is proved that there is no regular black hole solution when the scalar field is massless or has a “convex” potential. Surprisingly, while the scalar field has a growing mode around the local minimum of the potential, there is no growing mode around the local maximum. This implies that the local maximum is a kind of “attractor” of the asymptotic scalar field. We give two examples of the new black hole solutions with a nontrivial scalar field configuration numerically in the symmetric or asymmetric double well potential models. We study the stability of these solutions by using the linear perturbation method in order to examine whether or not the scalar hair is physical. In the symmetric double well potential model, we find that the potential function of the perturbation equation is positive semidefinite in some wide parameter range and that the new solution is stable. This implies that the black hole no-hair conjecture is violated in asymptotically AdS spacetime.
- 23 February 2000
- Published by American Physical Society (APS) in Physical Review D
- Vol. 61 (6)
Violation of the cosmic no hair conjecture in the Einstein-Maxwell-dilaton system
The cosmic no hair conjecture is tested in the spherically symmetric Einstein-Maxwell-dilaton~(EMD) system with a positive cosmological constant $\Lambda$. Firstly, we analytically show that once gravitational collapse occurs in the massless dilaton case, the system of field equations breaks down inevitably in outer communicating regions or at the boundary provided that a future null infinity ${\cal I}^+$ exists. Next we find numerically the static black hole solutions in the massive dilaton case and investigate their properties for comparison with the massless case. It is shown that their Abbott-Deser~(AD) mass are infinite, which implies that a spacetime with finite AD mass does not approach a black hole solution after the gravitational collapse. These results suggest that ${\cal I}^+$ cannot appear in the EMD system once gravitational collapse occurs and hence the cosmic no hair conjecture is violated in both the massless and the massive cases, in contrast to general relativity.Comment: 9 pages, REVtex, 5 figures, to appear in Phys. Rev.- 23 February 2000
- Published by American Physical Society (APS) in Physical Review D
- Vol. 61 (6)
Violation of the cosmic no hair conjecture in the Einstein-Maxwell-dilaton system
The cosmic no hair conjecture is tested in the spherically symmetric Einstein-Maxwell-dilaton~(EMD) system with a positive cosmological constant $\Lambda$. Firstly, we analytically show that once gravitational collapse occurs in the massless dilaton case, the system of field equations breaks down inevitably in outer communicating regions or at the boundary provided that a future null infinity ${\cal I}^+$ exists. Next we find numerically the static black hole solutions in the massive dilaton case and investigate their properties for comparison with the massless case. It is shown that their Abbott-Deser~(AD) mass are infinite, which implies that a spacetime with finite AD mass does not approach a black hole solution after the gravitational collapse. These results suggest that ${\cal I}^+$ cannot appear in the EMD system once gravitational collapse occurs and hence the cosmic no hair conjecture is violated in both the massless and the massive cases, in contrast to general relativity.Comment: 9 pages, REVtex, 5 figures, to appear in Phys. Rev.