Magnetogenesis and the generation of primordial gravitatoinal waves during cosmic inflation

• Project/Area Number: 17J09103
• Research Category: Grant-in-Aid for JSPS Fellows
• Allocation Type: Single-year Grants
• Section: 国内
• Research Field: Particle/Nuclear/Cosmic ray/Astro physics
• Research Institution: Kyoto University
• Principal Investigator: 藤田 智弘 京都大学, 理学研究科, 特別研究員(PD)
• Project Period (FY): 2017-04-26 – 2020-03-31
• Project Status: Completed (Fiscal Year 2019)
• Budget Amount: ¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000); Fiscal Year 2019: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000); Fiscal Year 2018: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000); Fiscal Year 2017: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
• Keywords: 宇宙論 / 宇宙磁場 / カイラル磁場効果 / 原始重力波 / インフレーション理論

Outline of Annual Research Achievements

初期宇宙で作られた宇宙磁場は、そのまま現在の宇宙まで何もせず残るのではなく、プラズマとの相互作用を通じて発展する。磁場とプラズマの共進化を記述するには磁気流体力学が標準的に使われているが、その中でカイラル磁場効果という新しい現象が近年注目を集めている。それは、温度が高く荷電粒子の質量が無視できる状況において、右巻きと左巻き荷電粒子の数に違いがある（カイラル非対称性）と、その差に比例した誘起電流が流れるという効果である。本年度はこの効果に注目し、共同研究者とともに磁場は全く無いが荷電粒子のカイラル非対称性はあるという初期条件から磁場がどのように生成され、その後どのように発展していくかを数値計算で丹念に調べるとともに、近似的に成り立つ解析的な式を導いた。プラズマ流体のゆらぎ（速度場）が無視できるような状況（レイノルズ数が小さい）では、最近発見されたように Chiral Magnetic Effect assisted inverse cascade という、通常のヘリカル磁場が示す Inverse cascadeとはスケーリングの異なる自己相似解があることを確認した上で、そこに対数補正が入ることを示した。反対に流体の速度場が無視できない状況（レイノルズ数が１よりずっと大きい）では、カイラル非対称性から生成されたヘリカル磁場の発展は、よく知られた通常の Inverse cascade のスケーリングによく乗ることを発見した。この研究によって、宇宙論的な状況のみならず高温下のパリティが破れた系において磁場がどのように生成・発展するかの重要な知見が得られた。原理的には、このカイラル磁場効果だけから磁場生成も可能であるが、より現実的にはカイラル非対称性だけでなく、ヘリカルな磁場も同時に存在する初期条件がもっともらしい。その場合に、どのような磁場が生き残るのかは今後の研究課題としたい。

Research Progress Status

令和元年度が最終年度であるため、記入しない。

Strategy for Future Research Activity

令和元年度が最終年度であるため、記入しない。

Research Products

• [Int'l Joint Research] ジュネーブ大学/CERN(欧州原子核研究機構)/スイス連邦工科大学ローザンヌ校(スイス)
• [Int'l Joint Research] 上海交通大学(中国)
• [Int'l Joint Research] Nikhef(オランダ)
• [Int'l Joint Research] CEICO(チェコ)
• [Journal Article] Primordial tensor non-gaussianity from massive gravity (2020)
  • Author(s): Fujita Tomohiro、Mizuno Shuntaro、Mukohyama Shinji
  • Journal Title: Journal of Cosmology and Astroparticle Physics Volume: 2020 Issue: 01 Pages: 023-023
  • DOI: 10.1088/1475-7516/2020/01/023
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] DANCE: Dark matter Axion search with riNg Cavity Experiment (2020)
  • Author(s): Michimura Yuta, Oshima Yuka, Watanabe Taihei, Kawasaki Takuya, Takeda Hiroki, Ando Masaki, Nagano Koji, Obata Ippei, Fujita Tomohiro
  • Journal Title: Journal of Physics: Conference Series Volume: 1468 Issue: 1 Pages: 012032-012032
  • DOI: 10.1088/1742-6596/1468/1/012032
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Axion Dark Matter Search with Interferometrie Gravitational Wave Detectors (2020)
  • Author(s): Nagano Koji、Obata Ippei、Fujita Tomohiro、Michimura Yuta
  • Journal Title: Journal of Physics: Conference Series Volume: 1468 Issue: 1 Pages: 012027-012027
  • DOI: 10.1088/1742-6596/1468/1/012027
  • Peer Reviewed / Open Access
• [Journal Article] Gravitational Waves from Primordial Magnetic Fields via Photon-Graviton Conversion (2020)
  • Author(s): Tomohiro Fujita、Kohei Kamada、Yuichiro Nakai
  • Journal Title: arXiv e-Print: 2002.07548 [astro-ph.CO] Volume: －
  • Open Access
• [Journal Article] Generation of chiral asymmetry via helical magnetic fields (2020)
  • Author(s): Schober Jennifer、Fujita Tomohiro、Durrer Ruth
  • Journal Title: Physical Review D Volume: 101 Issue: 10
  • DOI: 10.1103/physrevd.101.103028
  • Open Access / Int'l Joint Research
• [Journal Article] Perturbative description of bias tracers using consistency relations of LSS (2020)
  • Author(s): Tomohiro Fujita、Zvonimir Vlah
  • Journal Title: arXiv e-Print: 2003.10114 [astro-ph.CO] Volume: －
  • Open Access / Int'l Joint Research
• [Journal Article] Scale-invariant helical magnetic fields from inflation (2019)
  • Author(s): Fujita Tomohiro、Durrer Ruth
  • Journal Title: Journal of Cosmology and Astroparticle Physics Volume: 2019 Issue: 09 Pages: 008-008
  • DOI: 10.1088/1475-7516/2019/09/008
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Wide-angle redshift-space distortions at quasi-linear scales: cross-correlation functions from Zel’dovich approximation (2019)
  • Author(s): Taruya Atsushi、Saga Shohei、Breton Michel-Andr?s、Rasera Yann、Fujita Tomohiro
  • Journal Title: Monthly Notices of the Royal Astronomical Society Volume: 491 Issue: 3 Pages: 4162-4179
  • DOI: 10.1093/mnras/stz3272
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Footprint of two-form field: Statistical anisotropy in primordial gravitational waves (2019)
  • Author(s): Obata Ippei、Fujita Tomohiro
  • Journal Title: Physical Review D Volume: 99 Issue: 2 Pages: 023513-023513
  • DOI: 10.1103/physrevd.99.023513
  • Peer Reviewed / Open Access
• [Journal Article] Blue-tilted primordial gravitational waves from massive gravity (2019)
  • Author(s): Fujita Tomohiro、Kuroyanagi Sachiko、Mizuno Shuntaro、Mukohyama Shinji
  • Journal Title: Physics Letters B Volume: 789 Pages: 215-219
  • DOI: 10.1016/j.physletb.2018.12.025
  • Peer Reviewed / Open Access
• [Journal Article] Mixed non-gaussianity from axion-gauge field dynamics (2019)
  • Author(s): Fujita Tomohiro、Namba Ryo、Obata Ippei
  • Journal Title: Journal of Cosmology and Astroparticle Physics Volume: 2019 Issue: 04 Pages: 044-044
  • DOI: 10.1088/1475-7516/2019/04/044
  • Peer Reviewed / Open Access
• [Journal Article] Quantum entanglement in multi-field inflation (2018)
  • Author(s): Bolis Nadia、Fujita Tomohiro、Mizuno Shuntaro、Mukohyama Shinji
  • Journal Title: Journal of Cosmology and Astroparticle Physics Volume: 2018 Issue: 09 Pages: 004-004
  • DOI: 10.1088/1475-7516/2018/09/004
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Optical Ring Cavity Search for Axion Dark Matter (2018)
  • Author(s): Ippei Obata, Tomohiro Fujita, Yuta Michimura
  • Journal Title: Phys. Rev. Lett. Volume: 121 Issue: 16 Pages: 161301-161301
  • DOI: 10.1103/physrevlett.121.161301
  • Peer Reviewed / Open Access
• [Journal Article] Hunting for statistical anisotropy in tensor modes with B-mode observations (2018)
  • Author(s): Hiramatsu Takashi、Yokoyama Shuichiro、Fujita Tomohiro、Obata Ippei
  • Journal Title: Physical Review D Volume: 98 Issue: 8 Pages: 83522-83522
  • DOI: 10.1103/physrevd.98.083522
  • Peer Reviewed / Open Access
• [Journal Article] Tensor non-Gaussianity from axion-gauge-fields dynamics: parameter search (2018)
  • Author(s): Agrawal Aniket、Fujita Tomohiro、Komatsu Eiichiro
  • Journal Title: Journal of Cosmology and Astroparticle Physics Volume: 2018 Issue: 06 Pages: 027-027
  • DOI: 10.1088/1475-7516/2018/06/027
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Statistically Anisotropic Tensor Modes from Inflation (2018)
  • Author(s): Fujita, Tomohiro and Obata, Ippei and Tanaka, Takahiro and Yokoyama, Shuichiro
  • Journal Title: JCAP Volume: 1807 Issue: 07 Pages: 23-23
  • DOI: 10.1088/1475-7516/2018/07/023
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Does the detection of primordial gravitational waves exclude low energy inflation? (2018)
  • Author(s): Tomohiro Fujita, Ryo Namba, Yuichiro Tada
  • Journal Title: Physics Letters B Volume: 778 Pages: 17-21
  • DOI: 10.1016/j.physletb.2017.12.014
  • Peer Reviewed
• [Journal Article] Finding the chiral gravitational wave background of an axion-SU(2) inflationary model using CMB observations and laser interferometers (2018)
  • Author(s): Thorne Ben、Fujita Tomohiro、Hazumi Masashi、Katayama Nobuhiko、Komatsu Eiichiro、Shiraishi Maresuke
  • Journal Title: Physical Review D Volume: 97 Issue: 4 Pages: 043506-043506
  • DOI: 10.1103/physrevd.97.043506
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Does Anisotropic Inflation produce a small statistical anisotropy? (2018)
  • Author(s): Tomohiro Fujita and Ippei Obata
  • Journal Title: JCAP Volume: 1801 Issue: 01 Pages: 049-067
  • DOI: 10.1088/1475-7516/2018/01/049
  • Peer Reviewed / Open Access
• [Presentation] Chiral Magnetohydrodynamics in Cosmology (2020)
  • Author(s): Tomohiro Fujita
  • Organizer: Physics at the Cosmic Frontier
  • Int'l Joint Research / Invited
• [Presentation] Hunting Axion Dark Matter with New Techniques (2019)
  • Author(s): Tomohiro Fujita
  • Organizer: Beyond general relativity beyond cosmological standard model
  • Int'l Joint Research / Invited
• [Presentation] Axion Dark Matter Search with Gravitational Wave Detectors (2019)
  • Author(s): Tomohiro Fujita
  • Organizer: APPC2019 14th Asia-Pacific Physics Conference
  • Int'l Joint Research / Invited
• [Presentation] Monkey Theory: a general and simple theory of bias expansion (2019)
  • Author(s): Tomohiro Fujita
  • Organizer: PTchat@Kyoto
  • Int'l Joint Research
• [Presentation] 原始惑星系円盤の偏光観測による暗黒物質アクシオンの探査 (2019)
  • Author(s): 藤田智弘、田崎亮、當真賢二
  • Organizer: 日本物理学会 秋季大会
• [Presentation] New Axion Dark Matter Search with Proto-Planetary Disks (2019)
  • Author(s): Tomohiro Fujita
  • Organizer: Topics in Astroparticle and Underground Physics
  • Int'l Joint Research
• [Presentation] Hunting Axion Dark Matter with New Techniques (2019)
  • Author(s): Tomohiro Fujita
  • Organizer: JGRG29
  • Int'l Joint Research
• [Presentation] Novel Ways to Hunt Axion Dark Matter: Observation and Experiment (2019)
  • Author(s): Tomohiro Fujita
  • Organizer: Winter Mini Whorkshop on Gravity and Cosmology
  • Int'l Joint Research
• [Presentation] Search for Axion Dark Matter with New Approaches (2019)
  • Author(s): Tomohiro Fujita
  • Organizer: FAPESP&JSPS Whorkshop on dark energy, dark matter and galaxies
  • Int'l Joint Research
• [Presentation] Primordial Gravitational Waves in a Massive Graviton Theory (2018)
  • Author(s): Tomohiro Fujita
  • Organizer: Essential next steps for gravity and cosmology
  • Int'l Joint Research
• [Presentation] インフレーション中に作られる重力波の 振幅と非ガウス性と観測可能性 (2018)
  • Author(s): 藤田智弘, A. Agrawal, 小松英一郎
  • Organizer: 物理学会
• [Presentation] インフレーション中に作られる重力波の振幅と非ガウス性と観測可能性 (2018)
  • Author(s): 藤田智弘
  • Organizer: 日本物理学会
• [Presentation] インフレーションでの重力波生成と種々の観測量 (2017)
  • Author(s): 藤田智弘
  • Organizer: 日本物理学会
• [Presentation] Statistically Anisotropic Primordial Gravitational Waves from Gauge Field (2017)
  • Author(s): Tomohiro Fujita
  • Organizer: JGRG
  • Int'l Joint Research
• [Presentation] Primordial Gravitational wavesfrom gauge fields during inflation (2017)
  • Author(s): Tomohiro Fujita
  • Organizer: CosPa
  • Int'l Joint Research
• [Presentation] Gravitational wave production during inflation revisited (2017)
  • Author(s): Tomohiro Fujita
  • Organizer: COSMO
  • Int'l Joint Research
• [Presentation] Does the detection of primordial gravitational waves exclude low energy inflation? (2017)
  • Author(s): Tomohiro Fujita
  • Organizer: PASCOS
  • Int'l Joint Research