| Project/Area Number |
16540264
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Particle/Nuclear/Cosmic ray/Astro physics
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| Research Institution | Osaka City University |
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Principal Investigator |
NAKAO Ken-ichi Osaka City University, Graduate School of Science, Associate Professor, 大学院理学研究科, 助教授 (90263061)
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| Project Period (FY) |
2004 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 2006: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2005: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2004: ¥600,000 (Direct Cost: ¥600,000)
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| Keywords | higher dimensional gravity / topological defect / inflationary universe / naked singularity / cosmic censorship hypothesis / gravitational lens / gravitational wave / 重量崩壊 / インフレーション宇宙モデル / ブレーンワールド・シナリオ / 宇宙論 / 重力崩壊 / ブレーンワールド / ブラックストリング |
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| Research Abstract |
It is a purpose of this research project to get knowledge about the gravitational collapse to form black strings as a peculiar phenomenon under the higher dimensional gravity. And further, using the knowledge obtained, I would study the gravitational collapse of cosmic strings and domain walls whose have infinite extent of energy distribution.
Together with my collaborators, I investigated 4-dimensional spacelike hypersurfaces on which a mass distributes homogeneously within an ellipsoidal region. We search for apparent horizons on these spacelike hypersurfaces and confirm the so-called hyperhoop conjecture about the necessary and sufficient condition for the formations of black objects in higher dimensional spacetime.
Together with my collaborators, I proposed a scenario of the black string formation by the collisions and mergers of type I cosmic strings and found that even if the tension of the type I cosmic string is almost equal to the energy scale of electroweek phase transition, the black strings will form if such type I cosmic strings exist in out universe.
Since a domain wall has a 2-dimantional spatial extent, its spatial codimension is two in the 5-dimensional brane world scenario. Thus a domain wall in the 5-dimensional brane world scenario will behave as a cosmic string in 4-dimensional spacetime. In general it is very difficult to treat a spacetime singularity with spatial codimension 2. Thus I also studied the gravitational collapse with cylindrical symmetry, which form a spacetime singularity with codimension 2. Further, I studied the inflation which occurs within a topological defect, and the cosmological gravitational lensing effects which might observationally reveal the existence of black objects in our universe.
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