Gravitational collapse and spacetime singularities in quantum gravity

2012 Fiscal Year Final Research Report

• Project/Area Number: 21740190
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Single-year Grants
• Research Field: Particle/Nuclear/Cosmic ray/Astro physics
• Research Institution: Rikkyo University
• Principal Investigator: HARADA Tomohiro 立教大学, 理学部, 准教授 (60402773)
• Project Period (FY): 2009 – 2012
• Keywords: 相対論 / 重力理論

Research Abstract

We have revealed the relationship between quantisation ambiguities in quantum cosmology and the absence of spacetime singularity, deduced the astrophysical observational implications of superextremal Kerr spacetimes and wormhole structures, both of which may be possible under significant quantum gravity effects, and indicated the possibility of particle collision near the horizon of near-extremal rotating black holes of which the centre-of-mass energy might reach the Planck scale.

Research Products

• [Journal Article] Renormalization groupapproach to Einstein-Rosen waves (2013)
  • Author(s): Tomohiro Harada and Sanjay Jhingan
  • Journal Title: Phys. Rev. D Volume: 87(6) Pages: 7
  • URL: http://dx.doi.org/10.1103/PhysRevD.87.064043
  • Peer Reviewed
• [Journal Article] ブラックホールは天然の粒子加速器になるか (2013)
  • Author(s): 原田知広、木村匡志
  • Journal Title: 日本物理学 Volume: 第68巻第2号 Pages: 102
• [Journal Article] Signed magnification sums for general spherical lenses (2013)
  • Author(s): Naoki Tsukamoto and Tomohiro Harada
  • Journal Title: Phys. Rev. D Volume: 87(2) Pages: 6
  • URL: http://dx.doi.org/10.1103/PhysRevD.87.024024
  • Peer Reviewed
• [Journal Article] Can we distinguish between black holes and wormholes by their Einstein ring systems (2012)
  • Author(s): Naoki Tsukamoto, Tomohiro Harada and Kohji Yajima
  • Journal Title: Phys. Rev. D Volume: 86(10) Pages: 6
  • URL: http://dx.doi.org/10.1103/PhysRevD.86.104062
  • Peer Reviewed
• [Journal Article] Upperlimits of particle emission from high-energy collision and reaction near a maximally rotating Kerr black hole (2012)
  • Author(s): Tomohiro Harada, Hiroya Nemoto and Umpei Miyamoto
  • Journal Title: Phys. Rev. D Volume: 86(2) Pages: 1
  • URL: http://dx.doi.org/10.1103/PhysRevD.86.069902, http://dx.doi.org/10.1103/PhysRevD.86.024027
  • Peer Reviewed
• [Journal Article] Effect of a weak electromagnetic field on particle acceleration by a rotating black hole (2012)
  • Author(s): Takahisa Igata, Tomohiro Harada and Masashi Kimura
  • Journal Title: Phys. Rev. D Volume: 85(10) Pages: 11
  • URL: http://dx.doi.org/10.1103/PhysRevD.85.104028
  • Peer Reviewed
• [Journal Article] Collision of an object in the transition from adiabatic inspiral to plunge around a Kerr black hole (2011)
  • Author(s): Tomohiro Harada and Masashi Kimura
  • Journal Title: Phys. Rev. D Volume: 84(12) Pages: 8
  • URL: http://dx.doi.org/10.1103/PhysRevD.84.124032
  • Peer Reviewed
• [Journal Article] Uniqueness of static spherically symmetric vacuum solutions in the IR limit of nonrelativistic quantum gravity (2011)
  • Author(s): Tomohiro Harada, Umpei Miyamoto and Naoki Tsukamoto
  • Journal Title: J. Phys.: Conf. Ser Volume: 314
  • URL: http://dx.doi.org/10.1088/1742-6596/314/1/012120
  • Peer Reviewed
• [Journal Article] Discretisation parameter and operator ordering in loop quantum cosmology with the cosmological constant (2011)
  • Author(s): Tomo Tanaka, Fumitoshi Amemiya, Masahiro Shimano, Tomohiro Harada and Takashi Tamaki
  • Journal Title: Phys. Rev. D Volume: 83(10) Pages: 14
  • URL: http://dx.doi.org/10.1103/PhysRevD.83.104049
  • Peer Reviewed
• [Journal Article] The Japanese space gravitational wave antenna: DECIGO (2011)
  • Author(s): Seiji Kawamura et al. (31th among 145 authors
  • Journal Title: Class. Quantum Grav Volume: 28(9) Pages: 12
  • URL: http://dx.doi.org/10.1088/0264-9381/28/9/094011
  • Peer Reviewed
• [Journal Article] Collision of two general geodesic particles around a Kerr black hole (2011)
  • Author(s): Tomohiro Harada and Masashi Kimura
  • Journal Title: Phys. Rev. D Volume: 83(8) Pages: 9
  • URL: http://dx.doi.org/10.1103/PhysRevD.83.084041
  • Peer Reviewed
• [Journal Article] Collision of an innermost stable circular orbit particle around a Kerr black hole (2011)
  • Author(s): Tomohiro Harada and Masashi Kimura
  • Journal Title: Phys. Rev. D Volume: 83(2) Pages: 11
  • URL: http://dx.doi.org/10.1103/PhysRevD.83.024002
  • Peer Reviewed
• [Journal Article] Uniqueness of static spherically symmetric vacuum solutions in the IR limit of Horava-Lifshitz gravity (2011)
  • Author(s): Tomohiro Harada, Umpei Miyamoto and Naoki Tsukamoto
  • Journal Title: Int. J.Mod. Phys.D Volume: 20(1) Pages: 111-118
  • URL: http://dx.doi.org/10.1142/S021827181101865
  • Peer Reviewed
• [Journal Article] Observational Testability of Kerr bound in X-ray Spectrum of Black-Hole Candidates (2011)
  • Author(s): Rohta Takahashi and Tomohiro Harada
  • Journal Title: Class. Quant. Grav. Volume: 27(7) Pages: 21
  • URL: http://dx.doi.org/10.1088/0264-9381/27/7/075003
  • Peer Reviewed
• [Journal Article] Black hole candidates and the Kerr bound (2010)
  • Author(s): Tomohiro Harada and Rohta Takahashi
  • Journal Title: J. Phys.: Conf. Ser. (2011), as a contribution to the Proceedings of Spanish Relativity Meeting (ERE 2010): Gravity as a Crossroad in Physics Volume: 314 Pages: 6-10
  • URL: http://dx.doi.org/10.1088/1742-6596/314/1/012084
  • Peer Reviewed
• [Journal Article] Visible borders of spacetime generated by high-energy collisions (2010)
  • Author(s): Ken-ichi Nakao, Tomohiro Harada and Umpei Miyamoto
  • Journal Title: Phys. Rev. D Volume: 82(12) Pages: 4
  • URL: http://dx.doi.org/10.1103/PhysRevD.82.121501
  • Peer Reviewed
• [Journal Article] Can a primordial black hole or wormhole grow as fast as the universe (2010)
  • Author(s): B.J. Carr, Tomohiro Harada and Hideki Maeda
  • Journal Title: Class. Quant. Grav. Volume: 27(18) Pages: 28
  • URL: http://dx.doi.org/10.1088/0264-9381/27/18/183101
  • Peer Reviewed
• [Journal Article] Outflows from accreting super-spinars (2010)
  • Author(s): Cosimo Bambi, Tomohiro Harada, RohtaTakahashi and Naoki Yoshida
  • Journal Title: Phys. Rev. D Volume: 81(10) Pages: 12
  • URL: http://dx.doi.org/10.1103/PhysRevD.81.104004
  • Peer Reviewed
• [Journal Article] DECIGO and DECIGO pathfinder (2010)
  • Author(s): Masaki Ando et al.
  • Journal Title: Class. Quant. Grav. Volume: 27(8) Pages: 10
  • URL: http://dx.doi.org/10.1088/0264-9381/27/8/084010
  • Peer Reviewed
• [Journal Article] Accretion process onto super-spinning objects (2009)
  • Author(s): Cosimo Bambi, Katherine Freese, Tomohiro Harada, Rohta Takahashi and Naoki Yoshida
  • Journal Title: Phys. Rev. D Volume: 80(10) Pages: 10
  • URL: http://dx.doi.org/10.1103/PhysRevD.80.104023
  • Peer Reviewed
• [Journal Article] Observational constraints on a power spectru from super-inflation in Loop Quantum Cosmology (2009)
  • Author(s): Masahiro Shimano and Tomohiro Harada,''
  • Journal Title: Phys. Rev. D Volume: 80(6) Pages: 17
  • URL: http://dx.doi.org/10.1103/PhysRevD.80.063538
  • Peer Reviewed
• [Journal Article] Relativistic Gravitational Collapse of a Cylindrical Shell of Dust II: SettlingDown Boundary Condition (2009)
  • Author(s): Ken-ichi Nakao, Tomohiro Harada, Yasunari Kurita and Yoshiyuki Morisawa
  • Journal Title: Prog. Theor. Phys. Volume: 122(2) Pages: 521-541
  • URL: http://dx.doi.org/10.1143/PTP.122.521
  • Peer Reviewed
• [Journal Article] Einstein-Rosen waves and the self-similarity hypothesis in cylindrical symmetry (2009)
  • Author(s): Tomohiro Harada, Ken-ichi Nakao and Brien C. Nolan
  • Journal Title: Phys. Rev. D Volume: 80(2) Pages: 15
  • URL: http://dx.doi.org/10.1103/PhysRevD.80.109903, http://dx.doi.org/10.1103/PhysRevD.80.024025
  • Peer Reviewed
• [Journal Article] Singularities and self-similarity in gravitational collapse' (2009)
  • Author(s): Tomohiro Harada
  • Journal Title: a plenary talk given at the Hayashibara Forum at IHES on Singularities, 20-23 Nov 2006, Bures-sur-Yvette, France, Advanced Studies in Pure Mathematics Volume: 55 Pages: 15-30
  • URL: http://arxiv.org/abs/arXiv:0904.4770
  • Peer Reviewed
• [Journal Article] Self-similar black holes in an accelerated universe (2009)
  • Author(s): Tomohiro Harada
  • Journal Title: AIP Conf. Proc. (Physics and Mathematics of Gravitation: the Proceedings of the Spanish Relativity Meeting 2008, 15 - 19 Sep 2008, Salamanca, Spain", ed. K.E. Kunze, M. Mars and M.A. Vazquez-Mozo, (American Insitute of Physics, New York, 2009)) Volume: 1122 Pages: 288-291
  • URL: http://dx.doi.org/10.1063/1.3141296
  • Peer Reviewed
• [Journal Article] DECIGO: The Japanese space gravitational wave antenna (2009)
  • Author(s): Shuichi Sato et al. (31st among 135 authors)
  • Journal Title: J. Phys. Conf. Ser Volume: 154
  • URL: http://dx.doi.org/10.1088/1742-6596/154/1/012040
  • Peer Reviewed
• [Journal Article] DECIGO pathfinder (2009)
  • Author(s): Masaki Ando et al. (33rd among 137 authors)
  • Journal Title: Class. Quantum Grav. Volume: 26
  • URL: http://dx.doi.org/10.1088/0264-9381/26/9/094019
  • Peer Reviewed
• [Journal Article] Wave Effect in Gravitational Lensing by the EllisWormhole
  • Author(s): Chul-Moon Yoo, Tomohiro Harada and Naoki Tsukamoto
  • Journal Title: Physical Review D Volume: YITP-13-15 RUP-13-3, arXiv:1302.7170
  • URL: http://dx.doi.org/10.1103/PhysRevD.87.084045
  • Peer Reviewed
• [Journal Article] Weak cosmic censorship in gravitational collapse with astrophysical parameter values
  • Author(s): Umpei Miyamoto, Sanjay Jhingan and Tomohiro Harada
  • Journal Title: Progress of Theoretical and Experimental Physics Volume: (accepted)
  • URL: http://dx.doi.org/10.1093/ptep/ptt027
  • Peer Reviewed
• [Presentation] 分離宇宙条件の一般化へ向けて (2013)
  • Author(s): 原田知広(立教大理・准教授)Bernard J. Carr (ロンドン大クインメアリ校)
  • Organizer: 日本物理学会第68回年次大会
  • Place of Presentation: 広島大学
  • Year and Date: 2013-03-29
• [Presentation] High-velocity collision of particles around a rapidly rotating black hole (2012)
  • Author(s): Tomohiro Harada
  • Organizer: The 7th International Conference onGravitation and Cosmology
  • Place of Presentation: Holida Inn Goa, Goa, India.
  • Year and Date: 20121214-16
• [Presentation] High-velocity collision of particles around a Kerr black hole and its implication (2012)
  • Author(s): Tomohiro Harada
  • Organizer: Nishinomiya Yukawa Symposium: New Waves in Gravity and Cosmology, 4-6Dec
  • Place of Presentation: Kyoto University, Kyoto, Japan. (poster and short talk)
  • Year and Date: 20121204-06
• [Presentation] High-velocity collision of particles around a rapidly rotating black hole (2012)
  • Author(s): Tomohiro Harada
  • Organizer: The21st Workshop on General Relativity and Gravitation in Japan
  • Place of Presentation: Tohoku University, Sendai, Japan
  • Year and Date: 20120926-29
• [Presentation] Upper limits of particle emission from high-energy collisionand reaction near a maximally rotating Kerr black hole (2012)
  • Author(s): Tomohiro Harada
  • Organizer: the RESCEU SYMPOSIUM ON GENERAL RELATIVITY AND GRAVITATION
  • Place of Presentation: University of Tokyo, Tokyo, Japan.
  • Year and Date: 20120000
• [Presentation] High-velocity collision of particles around a Kerr black hole and its implication (2012)
  • Author(s): Tomohiro Harada
  • Organizer: Gravity and Cosmology 2012, 18 Nov-21Dec
  • Place of Presentation: Kyoto University, Kyoto, Japan.
  • Year and Date: 2012-11-18
• [Presentation] 高速回転ブラックホール付近の高エネルギー粒子衝突による粒子放射に対する上限について (2012)
  • Author(s): 原田知広(立教大理・准教授)、宗像裕也(立教大理D3)、宮本雲平(立教大・先端科学計測センターPD
  • Organizer: 日本物理学会2012年秋季大会
  • Place of Presentation: 京都産業大学
  • Year and Date: 2012-09-12
• [Presentation] High-velocity collision of two general geodesic particles around a Kerr black hole (2012)
  • Author(s): Tomohiro Harada and Masashi Kimura
  • Organizer: the 13th Marcel Grossmann Meeting on recent developments in theoretical and experimental general relativity, gravitation, relativistic field theories
  • Place of Presentation: Stockholm University, Stockholm, Sweden
  • Year and Date: 2012-07-17
• [Presentation] High-velocity collision of an ISCO particle around a Kerr black hole (2012)
  • Author(s): Tomohiro Harada and Masashi Kimura
  • Organizer: the 13th Marcel Grossmann Meeting on recent developments in theoretical and experimental general relativity, gravitation, relativistic field theories
  • Place of Presentation: Stockholm University, Stockholm, Sweden.
  • Year and Date: 2012-07-17
• [Presentation] 重力波放射反作用を考慮したときの天体加速器としての Kerr ブラックホール (2012)
  • Author(s): 原田知広 立教大理・准教授、木村匡志(京大基研・学振特別研究員PD)
  • Organizer: 日本物理学会第67回年次大会
  • Place of Presentation: 関西学院大学
  • Year and Date: 2012-03-27
• [Presentation] 高速回転ブラックホール付近での天体の高速衝突 (2011)
  • Author(s): 原田知広(立教大理・准教授)、木村匡志(大阪市大数学研究所・専任研究員)
  • Organizer: 日本天文学会2011年春季年会予稿集(東北関東大震災のための年会中止に伴う特例措置)
  • Year and Date: 20110300
• [Presentation] Collision of geodesic particles around a Kerr black hole (2011)
  • Author(s): Tomohiro Harada
  • Organizer: IPMU Workshop on Black Holes
  • Place of Presentation: IPMU, Kashiwa, Japan
  • Year and Date: 20110221-0225
• [Presentation] Kerrブラックホール周りでの一般の測地的二粒子の衝突 (2011)
  • Author(s): 原田知広(立教大理・准教授)、木村匡志(京大基研・学振特別研究員 PD)
  • Organizer: 日本物理学会2011年秋季大会
  • Place of Presentation: 弘前大学
  • Year and Date: 2011-09-16
• [Presentation] Black hole candidates and the Kerr bound (2010)
  • Author(s): Tomohiro Harada
  • Organizer: The20th Workshop on General Relativity and Gravitation in Japan
  • Place of Presentation: YITP, Kyoto, Japan
  • Year and Date: 20100921-25
• [Presentation] Uniqueness of static spherically symmetric vacuum solutions in the IR limit of nonrelativistic quantum gravity (2010)
  • Author(s): Tomohiro Harada
  • Organizer: Spanish Relativity Meeting 2010
  • Place of Presentation: Palacio de Exposiciones yCongresos de Granada, Granada, Spain
  • Year and Date: 20100906-10
• [Presentation] ブラックホール候補天体とKerr限界 (2010)
  • Author(s): 高橋労太(理研・基礎科学特別研究員)、原田知広(立教大理・准教授)
  • Organizer: 日本物理学会秋季大会
  • Place of Presentation: 九州工業大学
  • Year and Date: 2010-09-14
• [Presentation] Black hole candidates and the Kerr bound (2010)
  • Author(s): Tomohiro Harada
  • Organizer: Spanish Relativity Meeting 2010
  • Place of Presentation: Palacio de Exposiciones yCongresos de Granada, Granada, Spain.
  • Year and Date: 2010-09-09
• [Presentation] 非相対論的量子重力の赤外極限における静的球対称解 (2010)
  • Author(s): 原田知広(立教大理・准教授)、宮本雲平(立教大理・ポストドクトラルフェロー)、塚本直樹(立教大理・M2)
  • Organizer: 日本物理学会第65回年次大会
  • Place of Presentation: 岡山大学
  • Year and Date: 2010-03-23
• [Presentation] Einstein-Rosen waves and the self-similarity hypothesis in cylindrical symmetry (2009)
  • Author(s): Tomohiro Harada, Ken-ichi Nakao and Brien C. Nolan
  • Organizer: The 12th Marcel Grossmann Meeting on recent developments in theoretical and experimental general relativity, gravitation, relativistic field theories
  • Place of Presentation: Unesco Headquarters, Paris, France
  • Year and Date: 20090712-18
• [Presentation] Einstein-Rosenwaves and the self-similarity hypothesis in cylindrical symmetry (2009)
  • Author(s): Tomohiro Harada
  • Organizer: The 19th Workshop on General Relativity and Gravitation in Japan
  • Place of Presentation: Rikkyo University, Tokyo, Japan
  • Year and Date: 2009-11-30
• [Presentation] Einstein-Rosen波と円筒対称時空における自己相似仮説II (2009)
  • Author(s): 原田知広(立教大理・准教授)、中尾憲一(大阪市立大・教授)、B.C.Nolan(ダブリン市立大・上級講師)
  • Organizer: 日本物理学会秋季大会
  • Place of Presentation: 甲南大学
  • Year and Date: 2009-09-10
• [Remarks]
  • URL: http://www2.rikkyo.ac.jp/~harada/