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Exploring the origin of density fluctuations and the evolution of the early Universe in the precision cosmology era

Research Project

Project/Area Number 15K05084
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeMulti-year Fund
Section一般
Research Field Particle/Nuclear/Cosmic ray/Astro physics
Research InstitutionSaga University

Principal Investigator

Takahashi Tomo  佐賀大学, 理工学部, 准教授 (60432960)

Project Period (FY) 2015-04-01 – 2019-03-31
Project Status Completed (Fiscal Year 2018)
Budget Amount *help
¥4,680,000 (Direct Cost: ¥3,600,000、Indirect Cost: ¥1,080,000)
Fiscal Year 2018: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2017: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2016: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2015: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Keywords初期宇宙 / 精密宇宙観測 / 密度揺らぎ / 重力波 / 複数場インフレーションモデル / インフレーション / 原始密度揺らぎ / 小スケールの揺らぎ / 初期密度揺らぎ / 宇宙背景放射
Outline of Final Research Achievements

Recent precise cosmological observations have revealed various aspects of the Universe: the current energy budget of the Universe, the properties of primordial density fluctuations, and so on. Nevertheless, our understanding of the early Universe is still far from complete. In this research project, the evolution of the early Universe and the origin of density fluctuations have been explored, particularly focusing on small scale density fluctuations and gravity waves. By assuming concrete specifications of some future observations, we have analyzed expected constraints on models of the early Universe, then investigated what kind of models can be well tested by future observations. We believe that our findings have many implications for the research on the early Universe.

Academic Significance and Societal Importance of the Research Achievements

本研究では、初期宇宙の研究ではこれまであまり考えられていなかった観測(量)についても、初期宇宙進化、および、密度揺らぎの起源モデルの検証に有用であることを、具体的に幾つかのモデルにおける理論予言の解析も行いつつ示した。この点は本研究の意義深い点の一つである。
初期宇宙進化、密度揺らぎの起源を探る研究は、究極的には宇宙誕生の謎に迫る架け橋となる研究であり、究極的な根源知を追求するもので、人類の文化の蓄積に資するものと考えている。この点が本研究の社会的意義である。

Report

(5 results)
  • 2018 Annual Research Report   Final Research Report ( PDF )
  • 2017 Research-status Report
  • 2016 Research-status Report
  • 2015 Research-status Report
  • Research Products

    (32 results)

All 2019 2018 2017 2016 2015 Other

All Int'l Joint Research (8 results) Journal Article (12 results) (of which Int'l Joint Research: 8 results,  Peer Reviewed: 12 results,  Open Access: 3 results,  Acknowledgement Compliant: 3 results) Presentation (12 results) (of which Int'l Joint Research: 11 results,  Invited: 6 results)

  • [Int'l Joint Research] McGill University(カナダ)

    • Related Report
      2018 Annual Research Report
  • [Int'l Joint Research] Chonnam National University/Institute for Basic Science(韓国)

    • Related Report
      2017 Research-status Report
  • [Int'l Joint Research] APC, Universite Paris Diderot(France)

    • Related Report
      2017 Research-status Report
  • [Int'l Joint Research] University of Helsinki(Finland)

    • Related Report
      2016 Research-status Report
  • [Int'l Joint Research] Utrecht University(Netherlands)

    • Related Report
      2016 Research-status Report
  • [Int'l Joint Research] University of Warsaw(Poland)

    • Related Report
      2016 Research-status Report
  • [Int'l Joint Research] University of Sussex(英国)

    • Related Report
      2016 Research-status Report
  • [Int'l Joint Research] Helsinki Institute of Physics(Finland)

    • Related Report
      2015 Research-status Report
  • [Journal Article] Probing primordial non-Gaussianity with 21 cm fluctuations from minihalos2019

    • Author(s)
      Sekiguchi, Toyokazu and Takahashi, Tomo and Tashiro, Hiroyuki and Yokoyama, Shuichiro
    • Journal Title

      JCAP

      Volume: 1902 Issue: 02 Pages: 33-33

    • DOI

      10.1088/1475-7516/2019/02/033

    • Related Report
      2018 Annual Research Report
    • Peer Reviewed / Open Access
  • [Journal Article] Sneutrinos as mixed inflaton and curvaton2018

    • Author(s)
      Haba Naoyuki、Takahashi Tomo、Yamada Toshifumi
    • Journal Title

      Journal of Cosmology and Astroparticle Physics

      Volume: 2018 Issue: 06 Pages: 11-11

    • DOI

      10.1088/1475-7516/2018/06/011

    • Related Report
      2018 Annual Research Report
    • Peer Reviewed / Open Access
  • [Journal Article] Back-Reaction of Gravitational Waves Revisited2018

    • Author(s)
      Brandenberger, Robert and Takahashi, Tomo
    • Journal Title

      JCAP

      Volume: 1807 Issue: 07 Pages: 40-40

    • DOI

      10.1088/1475-7516/2018/07/040

    • Related Report
      2018 Annual Research Report
    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] Probing the Universe through the Stochastic Gravitational Wave Background2018

    • Author(s)
      Kuroyanagi, Sachiko and Chiba, Takeshi and Takahashi, Tomo
    • Journal Title

      JCAP

      Volume: 1811 Issue: 11 Pages: 38-38

    • DOI

      10.1088/1475-7516/2018/11/038

    • Related Report
      2018 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Impact of EDGES 21-cm global signal on the primordial power spectrum2018

    • Author(s)
      Yoshiura, Shintaro and Takahashi, Keitaro and Takahashi, Tomo
    • Journal Title

      Physical Reivew D

      Volume: 98 Issue: 6 Pages: 63529-63529

    • DOI

      10.1103/physrevd.98.063529

    • Related Report
      2018 Annual Research Report
    • Peer Reviewed / Open Access
  • [Journal Article] Dark matter kinetic decoupling with a light particle2018

    • Author(s)
      Ayuki Kamada, Tomo Takahashi
    • Journal Title

      Journal of Cosmology and Astroparticle Physics

      Volume: 1801 Issue: 01 Pages: 047-047

    • DOI

      10.1088/1475-7516/2018/01/047

    • Related Report
      2017 Research-status Report
    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] New bound on low reheating temperature for dark matter in models with early matter domination2017

    • Author(s)
      Ki-Young Choi, Tomo Takahashi
    • Journal Title

      Physical Review D

      Volume: 96 Issue: 4 Pages: 041301-041301

    • DOI

      10.1103/physrevd.96.041301

    • Related Report
      2017 Research-status Report
    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] Refined study of isocurvature fluctuations in the curvaton scenario2017

    • Author(s)
      Naoya Kitajima, David Langlois, Tomo Takahashi, Shuichiro Yokoyama
    • Journal Title

      Journal of Cosmology and Astroparticle Physics

      Volume: 1712 Issue: 12 Pages: 042-042

    • DOI

      10.1088/1475-7516/2017/12/042

    • Related Report
      2017 Research-status Report
    • Peer Reviewed / Int'l Joint Research
  • [Journal Article] Mixed inflaton and spectator field models: CMB constraints and μ distortion2016

    • Author(s)
      Kari Enqvist, Toyokazu Sekiguchi, Tomo Takahashi
    • Journal Title

      Journal of Cosmology and Astroparticle Physics

      Volume: 04 Issue: 04 Pages: 057-057

    • DOI

      10.1088/1475-7516/2016/04/057

    • Related Report
      2016 Research-status Report
    • Peer Reviewed / Int'l Joint Research / Acknowledgement Compliant
  • [Journal Article] Late-time quantum backreaction of a very light nonminimally coupled scalar2016

    • Author(s)
      Drazen Glavan, Tomislav Prokopec, Tomo Takahashi
    • Journal Title

      Physical Review D

      Volume: 94 Issue: 8 Pages: 084053-084053

    • DOI

      10.1103/physrevd.94.084053

    • Related Report
      2016 Research-status Report
    • Peer Reviewed / Int'l Joint Research / Acknowledgement Compliant
  • [Journal Article] Strongly scale-dependent CMB dipolar asymmetry from super-curvature fluctuations2016

    • Author(s)
      Christian Byrnes, Guillem Domenech, Misao Sasaki, Tomo Takahashi
    • Journal Title

      Journal of Cosmology and Astroparticle Physics (JCAP)

      Volume: 1612 Issue: 12 Pages: 020-020

    • DOI

      10.1088/1475-7516/2016/12/020

    • Related Report
      2016 Research-status Report
    • Peer Reviewed / Int'l Joint Research / Acknowledgement Compliant
  • [Journal Article] Decaying dark matter and the tension in sigma_82015

    • Author(s)
      Kari Enqvist, Seshadri Nadathur, Toyokazu Sekiguchi, Tomo Takahashi
    • Journal Title

      Journal of Cosmology and Astroparticle Physics

      Volume: 09 Issue: 09 Pages: 067-067

    • DOI

      10.1088/1475-7516/2015/09/067

    • Related Report
      2015 Research-status Report
    • Peer Reviewed / Int'l Joint Research
  • [Presentation] Probing the early Universe with 21cm line2019

    • Author(s)
      Tomo Takahashi
    • Organizer
      The 2nd Korea-Japan bilateral workshop on String Axion Cosmology
    • Related Report
      2018 Annual Research Report
    • Int'l Joint Research / Invited
  • [Presentation] Probing the early Universe with 21cm line2019

    • Author(s)
      Tomo Takahashi
    • Organizer
      FAPESP-JSPS workshop on Dark Energy, Dark Matter and Galaxies
    • Related Report
      2018 Annual Research Report
    • Int'l Joint Research
  • [Presentation] Back-Reaction of Gravitational waves2018

    • Author(s)
      Tomo Takahashi
    • Organizer
      The first NRF-JSPS workshop in particle physics, cosmology, and gravitation
    • Related Report
      2018 Annual Research Report
    • Int'l Joint Research
  • [Presentation] Back-Reaction of Gravitational waves revisited2018

    • Author(s)
      Tomo Takahashi
    • Organizer
      Cosmo 2018
    • Related Report
      2018 Annual Research Report
    • Int'l Joint Research
  • [Presentation] Probing the early Universe: Perspectives from current and future cosmological observations2018

    • Author(s)
      高橋 智
    • Organizer
      第7回観測論的宇宙論ワークショップ
    • Related Report
      2018 Annual Research Report
    • Invited
  • [Presentation] Possible roles of a spectator field in the early Universe2017

    • Author(s)
      Tomo Takahashi
    • Organizer
      The origin and evolution of the Universe
    • Related Report
      2017 Research-status Report
    • Int'l Joint Research
  • [Presentation] How can we probe inflation and the origin of density fluctuations?2016

    • Author(s)
      Tomo Takahashi
    • Organizer
      JGRG 26
    • Place of Presentation
      Osaka City University
    • Year and Date
      2016-10-27
    • Related Report
      2016 Research-status Report
    • Int'l Joint Research / Invited
  • [Presentation] Aspects of Multi-field models of inflation2016

    • Author(s)
      Tomo Takahashi
    • Organizer
      APCTP workshop “New Perspectives on Cosmology”
    • Place of Presentation
      Asia Pacific Center for Theoretical Physics, Pohang, Korea
    • Year and Date
      2016-01-08
    • Related Report
      2015 Research-status Report
    • Int'l Joint Research
  • [Presentation] Aspects of Multi-field models of inflation2015

    • Author(s)
      Tomo Takahashi
    • Organizer
      2nd LeCosPA International Symposium
    • Place of Presentation
      Taipei,Taiwan
    • Year and Date
      2015-12-17
    • Related Report
      2015 Research-status Report
    • Int'l Joint Research / Invited
  • [Presentation] Decaying Dark Matter and Large Scale Structure2015

    • Author(s)
      Tomo Takahashi
    • Organizer
      Busan Workshop on Particle Physics, String theory and Cosmology
    • Place of Presentation
      Busan, Korea
    • Year and Date
      2015-12-02
    • Related Report
      2015 Research-status Report
    • Int'l Joint Research / Invited
  • [Presentation] Multi-field models of inflation and isocurvature fluctuations2015

    • Author(s)
      Tomo Takahashi
    • Organizer
      International Workshop on Particle Physics and Cosmology
    • Place of Presentation
      Tohoku University, Sendai, Japan
    • Year and Date
      2015-09-16
    • Related Report
      2015 Research-status Report
    • Int'l Joint Research / Invited
  • [Presentation] Mixed Inflaton and Spectator Field Models: CMB constraints and mu distortion2015

    • Author(s)
      Tomo Takahashi
    • Organizer
      Cosmo 2015
    • Place of Presentation
      University of Warsaw, Poland
    • Year and Date
      2015-09-09
    • Related Report
      2015 Research-status Report
    • Int'l Joint Research

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Published: 2015-04-16   Modified: 2022-02-22  

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