Primordial Black Holes and Gravitational Waves

• Project Area: Gravitational wave physics and astronomy: Genesis
• Project/Area Number: 20H04727
• Research Category: Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)
• Allocation Type: Single-year Grants
• Review Section: Science and Engineering
• Research Institution: The University of Tokyo
• Principal Investigator: 佐々木 節 東京大学, カブリ数物連携宇宙研究機構, 特任教授 (70162386)
• Project Period (FY): 2020-04-01 – 2022-03-31
• Project Status: Completed (Fiscal Year 2021)
• Budget Amount: ¥4,940,000 (Direct Cost: ¥3,800,000、Indirect Cost: ¥1,140,000); Fiscal Year 2021: ¥2,470,000 (Direct Cost: ¥1,900,000、Indirect Cost: ¥570,000); Fiscal Year 2020: ¥2,470,000 (Direct Cost: ¥1,900,000、Indirect Cost: ¥570,000)
• Keywords: インフレーション宇宙 / 原始ブラックホール / 量子的曲率揺らぎ / 重力波 / 原始非ガウス性 / 暗黒物質 / 宇宙論的重力波 / ホーキング輻射 / 重力レンズ / 宇宙の曲率揺らぎ

Outline of Research at the Start

近年LIGOなど大型重力波検出干渉計が稼働を始め，重力波の直接観測が可能になったことで，重力波による原始ブラックホール（PBH）形成の検証可能性が高まってきた。例えば申請者らは宇宙の冷たい暗黒物質（CDM）となり得る10の21乗グラム程度の小PBHが形成されるインフレーションモデルを提唱し，それが予言する宇宙論的背景重力波の観測がPBH＝CDM説の検証に決定的な役割を果たすことを示した。
本研究の目的は，こうした準備研究をさらに発展させ，様々なPBH形成モデルが予言する重力波を調べ，現在あるいは将来の重力波観測によってモデルを制限し，あるいは同定するための条件を明らかにすることである。

Outline of Annual Research Achievements

ここ数年の間に，原始ブラックホール（ＰＢＨ）の形成の際の曲率揺らぎの統計的非ガウス性の重要性の認識が高まってきた。本研究は，その共通認識を育てるうえで大きな貢献をした。主な具体的成果は以下のとおりである。
１．ＰＢＨが宇宙の暗黒物質となる具体的インフレーションモデル・非極小カ―バトンモデルを構成し，ＰＢＨ形成が非摂動的非ガウス性で決まることを明らかにした。また，その曲率揺らぎに付随して発生する宇宙論的重力波を使って，２０３０年代に打ち上げ予定のスペース重力波検出器LISAによってモデルの検証可能であることを明らかにした。
２．インフレーションを引き起こす場，インフラトン場のポテンシャルに，ほんの小さなステップが存在するだけで，その曲率揺らぎの確率分布が非摂動的非ガウス性を持つことを，簡単な例で明らかにした。さらに，モデルパラメーターによっては，たとえ揺らぎのスペクトルの振幅が大きくても，大きな曲率揺らぎの確率が完全にゼロとなり，通常のＰＢＨ形成が全く起こらないことがあることを示した。そして，この場合も含めて，このモデルではインフレーション最中にもブラックホールが形成される可能性を指摘した。
３．地上重力波検出器ＬＩＧＯなどによって中性子性ーブラックホール連星の合体からの重力波が観測されており，このブラックホールがＰＢＨであるかどうかが，大きな課題であった。そこでこのブラックホールがＰＢＨであるとする仮説を理論的に検証し，その可能性がほとんどありえないことを明確に示した。

Research Progress Status

令和3年度が最終年度であるため、記入しない。

Strategy for Future Research Activity

令和3年度が最終年度であるため、記入しない。

Research Products

• [Int'l Joint Research] USTC/Institute of Theoretical Physics, CAS(中国)
• [Int'l Joint Research] Pusan National University/APCTP(韓国)
• [Int'l Joint Research] Padova University(イタリア)
• [Int'l Joint Research] Princeton University/UCLA(米国)
• [Int'l Joint Research] National Taiwan University(その他の国・地域 台湾)
• [Int'l Joint Research]
• [Int'l Joint Research] University of Science and Technology/Institute of Theoretical Physics, CAS(中国)
• [Int'l Joint Research] APCTP/Pusan National University/Sogang University(韓国)
• [Int'l Joint Research] Taiwan National University/Institute of Astronmy and Astrophysics(台湾)
• [Int'l Joint Research] University of Heidelberg(ドイツ)
• [Int'l Joint Research] University of Padova(イタリア)
• [Int'l Joint Research]
• [Journal Article] Super-horizon resonant magnetogenesis during inflation (2023)
  • Author(s): Sasaki Misao、Vardanyan Valeri、Yingcharoenrat Vicharit
  • Journal Title: Physical Review D Volume: 107 Issue: 8 Pages: 083517-083517
  • DOI: 10.1103/physrevd.107.083517
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Non-Gaussianity effects on the primordial black hole abundance for sharply-peaked primordial spectrum (2022)
  • Author(s): Takahiko Matsubara, Misao Sasaki
  • Journal Title: Journal of Cosmology and Astroparticle Physics Volume: 10 Issue: 10 Pages: 094-094
  • DOI: 10.1088/1475-7516/2022/10/094
  • Peer Reviewed / Open Access
• [Journal Article] Graviton non-gaussianity in α-vacuum (2022)
  • Author(s): Sugumi Kanno, Misao Sasaki
  • Journal Title: Journal of High Energy Physics Volume: 8 Issue: 8 Pages: 210-210
  • DOI: 10.1007/jhep08(2022)210
  • Peer Reviewed / Open Access
• [Journal Article] Resolving information loss paradox with Euclidean path integral (2022)
  • Author(s): Chen Pisin、Sasaki Misao、Yeom Dong-Han、Yoon Junggi
  • Journal Title: International Journal of Modern Physics D Volume: 31 Issue: 14 Pages: 2242001-2242001
  • DOI: 10.1142/s0218271822420019
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] One small step for an inflaton, one giant leap for inflation: A novel non-Gaussian tail and primordial black holes (2022)
  • Author(s): Cai Yi-Fu、Ma Xiao-Han、Sasaki Misao、Wang Dong-Gang、Zhou Zihan
  • Journal Title: Physics Letters B Volume: 834 Pages: 137461-137461
  • DOI: 10.1016/j.physletb.2022.137461
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Primordial black hole formation from massless scalar isocurvature (2022)
  • Author(s): Yoo Chul-Moon、Harada Tomohiro、Hirano Shin’ichi、Okawa Hirotada、Sasaki Misao
  • Journal Title: Physical Review D Volume: 105 Issue: 10 Pages: 103538-103538
  • DOI: 10.1103/physrevd.105.103538
  • Peer Reviewed
• [Journal Article] Primordial black holes from CDM isocurvature perturbations (2022)
  • Author(s): Passaglia Samuel、Sasaki Misao
  • Journal Title: Physical Review D Volume: 105 Issue: 10 Pages: 103530-103530
  • DOI: 10.1103/physrevd.105.103530
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Beating the Lyth Bound by Parametric Resonance during Inflation (2021)
  • Author(s): Cai Yi-Fu, Jiang Jie, Sasaki Misao, Vardanyan Valeri (corresponding author), Zhou Zihan
  • Journal Title: Physical Review Letters Volume: 127 Issue: 25 Pages: 251301-251301
  • DOI: 10.1103/physrevlett.127.251301
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Exploring evaporating primordial black holes with gravitational waves (2021)
  • Author(s): Domenech Guillem、Takhistov Volodymyr、Sasaki Misao
  • Journal Title: Physics Letters B Volume: 823 Pages: 136722-136722
  • DOI: 10.1016/j.physletb.2021.136722
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Cosmology of strongly interacting fermions in the early universe (2021)
  • Author(s): Guillem Domenech and Misao Sasaki
  • Journal Title: Journal of Cosmology and Astroparticle Physics (JCAP) Volume: 6 Issue: 06 Pages: 30-30
  • DOI: 10.1088/1475-7516/2021/06/030
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Approximate gauge independence of the induced gravitational wave spectrum (2021)
  • Author(s): Guillem Domenech and Misao Sasaki
  • Journal Title: Physical Review D Volume: 103 Issue: 6 Pages: 63531-63531
  • DOI: 10.1103/physrevd.103.063531
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Gravitational wave constraints on the primordial black hole dominated early universe (2021)
  • Author(s): Guillem Domenech, Chunshan Lin and Misao Sasaki
  • Journal Title: Journal of Cosmology and Astroparticle Physics (JCAP) Volume: 4 Issue: 04 Pages: 62-62
  • DOI: 10.1088/1475-7516/2021/04/062
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Testing stochastic gravitational wave signals from primordial black holes with optical telescopes (2021)
  • Author(s): Sugiyama Sunao、Takhistov Volodymyr、Vitagliano Edoardo、Kusenko Alexander、Sasaki Misao、Takada Masahiro
  • Journal Title: Physics Letters B Volume: 814 Pages: 136097-136097
  • DOI: 10.1016/j.physletb.2021.136097
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Multi-field dark energy: Cosmic acceleration on a steep potential (2021)
  • Author(s): Y. Akrami, M. Sasaki, A. R. Solomon and V. Vardanyan
  • Journal Title: Physics Letters B Volume: 819 Pages: 136427-136427
  • DOI: 10.1016/j.physletb.2021.136427
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] On problems with cosmography in cosmic dark ages (2021)
  • Author(s): Aritra Banerjee, Eoin Colgain, Misao Sasaki, M. M. Sheikh-Jabbari and T. Yang
  • Journal Title: Physics Letters B Volume: 818 Pages: 136366-136366
  • DOI: 10.1016/j.physletb.2021.136366
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Primordial black holes and gravitational waves from resonant amplification during inflation (2020)
  • Author(s): Zhou Zihan、Jiang Jie、Cai Yi-Fu、Sasaki Misao、Pi Shi
  • Journal Title: Physical Review D Volume: 102 Issue: 10 Pages: 103527-103527
  • DOI: 10.1103/physrevd.102.103527
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Induced gravitational waves as a probe of thermal history of the universe (2020)
  • Author(s): Domenech Guillem、Pi Shi、Sasaki Misao
  • Journal Title: Journal of Cosmology and Astroparticle Physics Volume: 2020 Issue: 08 Pages: 017-017
  • DOI: 10.1088/1475-7516/2020/08/017
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Gravitational waves induced by scalar perturbations with a lognormal peak (2020)
  • Author(s): Pi Shi、Sasaki Misao
  • Journal Title: Journal of Cosmology and Astroparticle Physics Volume: 2020 Issue: 09 Pages: 037-037
  • DOI: 10.1088/1475-7516/2020/09/037
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] New measures to test modified gravity cosmologies (2020)
  • Author(s): Jiro Matsumoto, Teppei Okumura and Misao Sasaki
  • Journal Title: Journal of Cosmology and Astroparticle Physics (JCAP) Volume: 7 Issue: 07 Pages: 59-59
  • DOI: 10.1088/1475-7516/2020/07/059
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] A path(-integral) toward non-perturbative effects in Hawking radiation (2020)
  • Author(s): Pisin Chen, Misao Sasaki and Dong-han Yeom
  • Journal Title: International Journal of Modern Physics D Volume: 29 Issue: 12 Pages: 2050086-2050086
  • DOI: 10.1142/s0218271820500868
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Exploring Primordial Black Holes from the Multiverse with Optical Telescopes (2020)
  • Author(s): Kusenko Alexander、Sasaki Misao、Sugiyama Sunao、Takada Masahiro、Takhistov Volodymyr、Vitagliano Edoardo
  • Journal Title: Physical Review Letters Volume: 125 Issue: 18 Pages: 1-7
  • DOI: 10.1103/physrevlett.125.181304
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Could the black hole singularity be a field singularity? (2020)
  • Author(s): Guillem Domenech, Atsushi Naruko, Misao Sasaki and Christof Wetterich
  • Journal Title: IJMPD Volume: 29 Issue: 03 Pages: 2050026-2050026
  • DOI: 10.1142/s0218271820500261
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Universal infrared scaling of gravitational wave background spectra (2020)
  • Author(s): Cai Rong-Gen、Pi Shi、Sasaki Misao
  • Journal Title: Physical Review D Volume: 102 Issue: 8 Pages: 083528-083528
  • DOI: 10.1103/physrevd.102.083528
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Possible resolution of a spacetime singularity with field transformations (2020)
  • Author(s): Atsushi Naruko, Chul-Moon Yoo, Misao Sasaki
  • Journal Title: Progress of Theoretical and Experimental Physics Volume: 2020 Issue: 4 Pages: 1-8
  • DOI: 10.1093/ptep/ptaa028
  • Peer Reviewed / Open Access
• [Presentation] Primoridal Black Holes from Non-Perturbative Non-Gaussian Tails (2023)
  • Author(s): Misao Sasaki
  • Organizer: Testing Gravity 2023
  • Int'l Joint Research / Invited
• [Presentation] Inflation and Gravitational Wave Cosmology (2023)
  • Author(s): Misao Sasaki
  • Organizer: ISCO 2023
  • Int'l Joint Research / Invited
• [Presentation] Primordial Black Holes from Inflation (2023)
  • Author(s): Misao Sasaki
  • Organizer: NTU LeCosPA seminar
  • Int'l Joint Research / Invited
• [Presentation] Primordial Black Holes from Inflation (2023)
  • Author(s): Misao Sasaki
  • Organizer: KIAS seminar
  • Int'l Joint Research / Invited
• [Presentation] Primordial Black Holes from Inflation (2022)
  • Author(s): Misao Sasaki
  • Organizer: Symposium on Gravitational wave physics and astronomy: Genesis
  • Int'l Joint Research / Invited
• [Presentation] Primordial Black Holes from Inflation (2022)
  • Author(s): Misao Sasaki
  • Organizer: USTC colloquium
  • Int'l Joint Research / Invited
• [Presentation] Resolving information loss paradox with Euclidean path integral approach (2022)
  • Author(s): Misao Sasaki
  • Organizer: String Theory, Gravity and Cosmology (SGC 2022)
  • Int'l Joint Research / Invited
• [Presentation] Primordial Black Holes from Inflation (2022)
  • Author(s): Misao Sasaki
  • Organizer: Gravity: Current challenges in black hole physics and cosmology
  • Int'l Joint Research / Invited
• [Presentation] Lectures: Inflation and cosmological perturbations (2022)
  • Author(s): Misao Sasaki
  • Organizer: V institute of space sciences summer school: Modified gravities, inflation and primordial perturbations: theory and computing
  • Int'l Joint Research / Invited
• [Presentation] Multiple classical histories as a solution to the black hole information loss paradox (2022)
  • Author(s): Misao Sasaki
  • Organizer: KEK seminar
  • Int'l Joint Research / Invited
• [Presentation] Primordial Black Holes from Inflation (2022)
  • Author(s): Misao Sasaki
  • Organizer: 31st Texas Symposium on Relativistic Astrophysics
  • Int'l Joint Research / Invited
• [Presentation] Primordial Black Holes from Inflation (2022)
  • Author(s): Misao Sasaki
  • Organizer: APC seminar
  • Int'l Joint Research / Invited
• [Presentation] Inflation Breeds Primordial Black Holes (2022)
  • Author(s): Misao Sasaki
  • Organizer: ULB Solvay Colloquium
  • Int'l Joint Research / Invited
• [Presentation] Inflation as a farm to grow primordial black holes (2022)
  • Author(s): Misao Sasaki
  • Organizer: Higgs Centre Colloquium
  • Int'l Joint Research / Invited
• [Presentation] Primordial Black Holes from Inflation (2022)
  • Author(s): Misao Sasaki
  • Organizer: 9th Korea-Japan workshop on dark energy
  • Int'l Joint Research / Invited
• [Presentation] Cosmology - the quest for the birth and evolution of the Universe (2022)
  • Author(s): Misao Sasaki
  • Organizer: Lecture: Tongji University
  • Int'l Joint Research / Invited
• [Presentation] Primordial Black Holes from Inflation (2022)
  • Author(s): Misao Sasaki
  • Organizer: LMU ASC seminar
  • Int'l Joint Research / Invited
• [Presentation] Primordial Black Holes from Inflation (2022)
  • Author(s): Misao Sasaki
  • Organizer: Messengers of the very early universe: Gravitational Waves and Primordial Black Holes
  • Int'l Joint Research / Invited
• [Presentation] Primordial Black Holes may be Dark Matter of the Universe (2022)
  • Author(s): Misao Sasaki
  • Organizer: Padova University Physics Colloquium
  • Int'l Joint Research / Invited
• [Presentation] Primordial Black Holes and Gravitational Waves (2022)
  • Author(s): Misao Sasaki
  • Organizer: Indian Institute of Technology seminar
  • Int'l Joint Research / Invited
• [Presentation] PBHs from inflation and gravitational waves (2022)
  • Author(s): Misao Sasaki
  • Organizer: New observational windows on the high-scale origin of matter-antimatter asymmetry
  • Int'l Joint Research / Invited
• [Presentation] Primordial Black Holes from Inflation (2022)
  • Author(s): Misao Sasaki
  • Organizer: YKIS 2022a: Gravity - The Next Generation-
  • Int'l Joint Research / Invited
• [Presentation] 原始ブラックホールと重力波 (2022)
  • Author(s): 佐々木節
  • Organizer: 物理学会シンポジウム
  • Invited
• [Presentation] Primordial Black Holes and Cosmological Gravitational Waves (2021)
  • Author(s): Misao Sasaki
  • Organizer: IHP programme on Gravitational waves: a new messenger to explore the universe
  • Int'l Joint Research / Invited
• [Presentation] primordial black holes (2021)
  • Author(s): Misao Sasaki
  • Organizer: Quantum Gravity and Cosmology (A.D. Sakharov's centennial)
  • Int'l Joint Research / Invited
• [Presentation] primordial black holes and gravitational waves (2021)
  • Author(s): Misao Sasaki
  • Organizer: Lake Como School on Multi-Messenger in Astrophysics.
  • Int'l Joint Research / Invited
• [Presentation] primordial black holes - a few recent topics - (2021)
  • Author(s): Misao Sasaki
  • Organizer: APCTP seminar
• [Presentation] Primordial Black Holes and Cosmological Gravitational Waves (2021)
  • Author(s): Misao Sasaki
  • Organizer: Gravitational Wave Probes of Physics Beyond Standard Model
  • Int'l Joint Research / Invited
• [Presentation] Primordial Black Holes: Roles of isocurvature perturbations (2021)
  • Author(s): Misao Sasaki
  • Organizer: Black Holes Inside and Out
  • Int'l Joint Research / Invited
• [Presentation] Inflation and cosmological perturbations (2021)
  • Author(s): Misao Sasaki
  • Organizer: APCTP lectures
• [Presentation] Cosmology of Primordial Black Holes and Gravitational Waves (2021)
  • Author(s): Misao Sasaki
  • Organizer: 4th LeCosPA Symposium
  • Int'l Joint Research / Invited
• [Presentation] Primordial Black Holes Review (2021)
  • Author(s): Misao Sasaki
  • Organizer: AstroDark-2021
• [Presentation] Primordial black hole cosmology (2021)
  • Author(s): Misao Sasaki
  • Organizer: Recent Advances in Theoretical Cosmology and Astrophysics
  • Int'l Joint Research / Invited
• [Presentation] Gravitational Wave Cosmology - The Dawn has Arrived! - (2020)
  • Author(s): Misao Sasaki
  • Organizer: University of Groningen seminar
  • Int'l Joint Research / Invited
• [Presentation] Delta N formalism in cosmological perturbation theory (2020)
  • Author(s): Misao Sasaki
  • Organizer: APCTP lectures
  • Int'l Joint Research / Invited
• [Presentation] Primordial Black Holes and Cosmological Gravitational Waves (2020)
  • Author(s): Misao Sasaki
  • Organizer: GW genesis seminar
  • Int'l Joint Research / Invited
• [Presentation] Primordial Black Holes and Gravitational Waves (2020)
  • Author(s): Misao Sasaki
  • Organizer: ICTS Workshop on Less Travelled Path for Dark Matter
  • Int'l Joint Research / Invited
• [Presentation] Primordial Black Holes and Gravitational Waves (2020)
  • Author(s): Misao Sasaki
  • Organizer: Gordon Godfrey Workshop on Astrophysics
  • Int'l Joint Research / Invited
• [Presentation] Primordial Black Holes and Gravitational Waves (2020)
  • Author(s): Misao Sasaki
  • Organizer: 7th Korea-Japan Workshop on Dark Energy
  • Int'l Joint Research / Invited
• [Remarks]
  • URL: https://db.ipmu.jp/member/personal/566en.html
• [Funded Workshop] Non-linear aspects of cosmological gravitational waves (2022)