Probing the early universe by stochastic gravitational wave background
| Project/Area Number |
20K14461
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| Research Category |
Grant-in-Aid for Early-Career Scientists
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| Allocation Type | Multi-year Fund |
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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 |
皮 石 東京大学, カブリ数物連携宇宙研究機構, 客員准科学研究員 (60817518)
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| Project Period (FY) |
2020-04-01 – 2024-03-31
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| Project Status |
Completed (Fiscal Year 2023)
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| Budget Amount *help |
¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000)
Fiscal Year 2023: ¥260,000 (Direct Cost: ¥200,000、Indirect Cost: ¥60,000)
Fiscal Year 2022: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000)
Fiscal Year 2021: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2020: ¥2,210,000 (Direct Cost: ¥1,700,000、Indirect Cost: ¥510,000)
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| Keywords | gravitational waves / primordial black holes / curvature perturbation / inflation / ultra slow roll / δN formalism / pulsar timing array / LISA / pulsa timing array / curvaton scenario / swampland conjecture / cosmology |
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| Outline of Research at the Start |
The discovery of gravitational wave in 2015 marks the dawn of gravitational wave astronomy/cosmology. This is a new window to observe the beginning and evolution of our universe. In the next few decays, there will be many new gravitational-wave experiments, including the Japanese project KAGRA. This research is aimed to study the general and characteristic features of the stochastic gravitational-wave background originating from different sources in the early universe, which is helpful in both comprehending the physics of the early universe, and in seeking for such signals in the future.
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| Outline of Annual Research Achievements |
In the entire period of this program JP20K14461, I completed 13 papers (10 published, 3 in submission). Here is a summary of some representitive works.
1. Pi and Sasaki, Phys.Rev.Lett. 131 (2023) 1, 011002. We found a fully nonlinear expression for the curvature perturbation in single-field inflation models, which is very helpful in determining its statistical properties.
2. Cai, Pi, and Sasaki, Phys.Rev.D 102 (2020) 8, 083528. We show that under some general conditions, the GW spectra, no matter what sources they come from, has an universal infrared f^3 scaling.
3. Demenech and Pi, Sci.China Phys.Mech.Astron. 65 (2022) 3, 230411. We show that the nHz GW signal observed by pulsar timing arrays (NANOGrav, etc.) could indicate the presense of planet-mass PBHs.
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Report
(4 results)
Research Products
(30 results)
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[Journal Article] The Gravitational-wave physics II: Progress2021
Author(s)
Bian Ligong、Cai Rong-Gen、Cao Shuo、Cao Zhoujian、Gao He、Guo Zong-Kuan、Lee Kejia、Li Di、Liu Jing、Lu Youjun、Pi Shi、Wang Jian-Min、Wang Shao-Jiang、Wang Yan、Yang Tao、Yang Xing-Yu、Yu Shenghua、Zhang Xin
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Journal Title
Science China Physics, Mechanics & Astronomy
Volume: 64
Issue: 12
Pages: 120401-120401
DOI
Related Report
Peer Reviewed / Int'l Joint Research
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