| Project/Area Number |
22KF0085
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| Project/Area Number (Other) |
22F21316 (2022)
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| Research Category |
Grant-in-Aid for JSPS Fellows
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| Allocation Type | Multi-year Fund (2023)
Single-year Grants (2022) |
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| Section | 外国 |
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| Review Section |
Basic Section 15010:Theoretical studies related to particle-, nuclear-, cosmic ray and astro-physics
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| Research Institution | The University of Tokyo |
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Principal Investigator |
カンノン キップ (2023) 東京大学, 大学院理学系研究科(理学部), 教授 (50777886)
西澤 篤志 (2022) 東京大学, 大学院理学系研究科(理学部), 助教 (90569378)
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| Co-Investigator(Kenkyū-buntansha) |
KARMAKAR PURNENDU 東京大学, 大学院理学系研究科(理学部), 外国人特別研究員
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| Project Period (FY) |
2023-03-08 – 2024-03-31
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| Project Status |
Completed (Fiscal Year 2023)
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| Budget Amount *help |
¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 2023: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2022: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Keywords | metric affine gravity / cosmic expansion / cosmic structure / dark energy / gravitational waves / 一般時空幾何 / 重力波 / 観測的検証 / テレパラレル重力理論 |
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| Outline of Research at the Start |
一般相対性理論では時空は計量によって特徴付けられるが、一般には時空は捻れや非計量性といった時空幾何へと一般化することが可能である。宇宙加速膨張や特異点など一般相対性理論では説明が難しい現象があり、一般相対性理論を超えた重力理論の可能性について調べることは重力のより深い理解に不可欠である。そこで、本研究では、最新の重力波観測データを解析し、一般化された時空幾何の理論に関して様々な検証を行い、その性質についての知見を得る。
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| Outline of Annual Research Achievements |
Although GR is well established at small scales, GR faces challenges predicting dynamics on large scales, which motivated the hypotheses of dark energy and dark matter. Metric affine gravity (MAG) has been proposed to resolve some of these issues. In this fellowship, we aimed to develop observational tests of a subset of MAG, called symmetric teleparallel (STEGR), specifically f(Q) models, which are a function of nonmetricty (Q), alone. These models are stable and produce the same GW speed observed in the GW170817 event. We have considered three specific forms for f(Q): a power law, a logarithmic, and an exponential in Q.
For each model we have checked the ranges of parameters that produce background evolution consistent with observed cosmic expansion rate. We have checked the effective dark energy equation of state produced by each model. We have checked the parameters in the perturbations: effective gravitational coupling in the Poisson equation, the amplitude damping parameter in the propagation of GW, and performed a chi-squared error analysis to bound the model parameters. We found that the logarithmic, and one of the two branches of the exponential model are excluded by observational data, while we obtained bounds on the parameters of the power law and other branch of the exponential model.
Future observations of gravitational waves will play a crucial role in testing the theory as a probe independent and complementary to electromagnetic observations.
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