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수치상대론 연구의 최근 동향과 전망

Apr 19, 2007 at KPS meeting, Phoenix Park. 수치상대론 연구의 최근 동향과 전망. 강궁원 (KISTI). 목 차. Numerical relativity Recent progresses (in binary black hole coalescences) Search for the identity of Korean NR group Conclusion. I. 수치상대론 ( Numerical Relativity ). 1. 수치상대론이란 ?. Einstein ’ s equations:.

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수치상대론 연구의 최근 동향과 전망

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  1. Apr 19, 2007 at KPS meeting, Phoenix Park 수치상대론 연구의 최근 동향과 전망 강궁원(KISTI)

  2. 목 차 • Numerical relativity • Recent progresses (in binary black hole coalescences) • Search for the identity of Korean NR group • Conclusion

  3. I. 수치상대론(Numerical Relativity) 1.수치상대론이란? Einstein’s equations: One can obtain solutions in closed forms for special cases only: e.g., Schwarzschild BH, Kerr BH, FRW, …… For most dynamical cases, however, it is almost impossible to solve the equations analytically. One needs some other approach. 컴퓨터를 이용해서 수치적인 방법으로 아인슈타인 방정식의 해를 구하는 것 * Key Scenarios: Binary black hole mergers (e.g., BH-BH, NS-NS, NS-BH), Gravitational collapse of massive stars, Probes of strong field phenomenology, etc.

  4. 2. A bit of history • Head-on collision of two equal mass black holes: DeWitt (’76), Cadez (’71), Smarr (’75,’76,’77,’79), Eppley (’71), Anninos, Hobill, Seidel, Smarr & Suen (’95) • Critical phenomena: 1993, “Universality and Scaling in Gravitational Collapse of a Massless Scalar Field” by Choptuik • 3-D codes constructed in early-mid 90’s for BH simulation that were based on traditional ADM formalism generically proved to have stability problems • BSSN formulation: Baumgarte & Shapiro (1998), Nakamura & Shibata (1995), Much improved stability, A hyperbolic type of equations • 3D code: 2001, Alcubierre, Benger, Brugmann, Lanfermann, Nerger, Seidel, and Takahashi, 3D grazing collision of two BHs • Single relativistic star: 2002, Font, Gooddale, Iyer, Miller, Rezzolla, Seidel et al. • Binary black hole coalescences: 2005, Pretorius (0507), Campanelli, Lousto, Marronetti, Zlochower (0511), Baker, Centrella, Dae-Il Choi, Koppitz, van Meter (0511), Diener, Herrmann, Pollney, Schnetter, Seidel, Takahashi, Thornburg, Ventrella (0512)

  5. 3. 3+1 / ADM formalism: Traditional Approach(Choquet-Bruhat 1956, ADM 1962, York 1979) 3-metric: extrinsic curvature: Constraint equations: Evolution equations: where

  6. 4. NR and Gravitational Wave Detection Joseph Weber (c1960)

  7. Network of Interferometers LIGO Virgo GEO TAMA LIGO Louisiana 4000m AIGO Cited from H.J. Paik’s talk

  8. 중력파의 주요 Source - 블랙홀-블랙홀, 블랙홀-중성자별 등등의 충돌 - Cosmological perturbations - 초신성 폭발 • 중력파의 파형에 대한 구체적 정보 필요: “URGENT DEMAND FOR GW DETECTION!!”

  9. 전자기파 * 이론: Maxwell (1873) * 전하의 가속에 의해 발생 예상 * 검출: H. Hertz (1888) • 중력파 • * 이론: Einstein (1916) • 물질의 가속에 의해 발생 예상, • Transverse & spin 2 • 간접검출: Taylor & Hulse (’79) • 검출: K. Thorne(?) LIGO(?) ?

  10. II. Recent Progresses(in binary black hole coalescences) 1. EUREKA in BBH simulations!! Pretorius (0507), Campanelli, Lousto, Marronetti, Zlochower (0511), Baker, Centrella, Dae-Il Choi, Koppitz, van Meter (0511), • Full parameters:

  11. 2. Gravitational recoil or ‘kick’ calculations • In binary black hole mergers the gravitational radiation emitted could carry away a net flux of linear momentum. It implies that the black hole produced by the merger will get a recoil or kick. • The magnitude of the resulting recoil plays a crucial role in a variety of astrophysical contexts; Ex) Cosmological evolution of supermassive black holes, Growth and retention of intermediate-mass black holes in dense stellar clusters, etc.

  12. 1) Baker, Centrella, Choi et al. ‘06 • Nonspinning unequal masses: 1.5 : 1 • “Puncture” approach: Baker etal. ’06 • Constraint satisfying initial data allowing about 1-3 orbits before the formation of a common horizon • Evolved by the finite-differencing code, Handol, on an adaptive mesh refinement structure implemented via PARAMESH

  13. : a component of the Weyl curvature tensor extracted at 113 km/s 97 km/s 92 km/s • Time rate of change of radiated momentum: Newman & Todd ’80

  14. 2) Hermann et al. ‘07 • Equal mass but spinning cases • a = 0.4

  15. Big enhancement!! • Escape velocity from the center of dwarf elliptical galaxies: ~ 300 km/s

  16. lying in the orbital plane 3) Other works • Koppitz et al. ’07: Unequal mass with spinning • Campanelli et al. ’07: Unequal mass with misaligned spins

  17. Choi et al. ’07: Head-on with spins

  18. Campanelli et al. ’07: Equal mass with spins on the orbital plane

  19. Gonzalez et al. ’07: Equal mass with spins  at least 2500 km/s for appropriate alignments of spins

  20. III. Search for the identity of Korean NR group • Should we Korean NR group follow up the standard research topics in world wide NR communities? • Or, should we distinguish ourselves? • The main field such as BBH simulations is not only crowded but also competitive now. • We need to do something that no one is doing yet. • What is that?

  21. Some topics in considerations • Parameter space survey and Gravitational recoil kick calculations in BBH systems • Black hole scattering • Black hole factory • Simulations in alternative theories of gravity • Black String simulations • AdS soliton spacetime • Coalescences of two stars • etc.

  22. 『한국 수치상대론 연구회』 • 2004: 중력파 워킹 그룹 • 2005.3.16: Kick-off meeting, 서울대 • 2005.6.28: 수치상대론 연구회 결성 • ~ 2007.03: Monthly workshop(15회) and Schools(3회) • 2005, 2006년 여름: UBC 방문연구 • 2006.10.16: 최대일 박사 합류(브레인풀) • 2006.12.18~2007.01.17: 제1차 KISTI 방문연구프로그램 • KISTI 와 APCTP Topical Research Program 의 공동 후원

  23. <표1.수치상대론 연구회 발표 종합 (2005.06 - 2006.12)>

  24. <표2.수치상대론 연구회 참석인원 현황(2005.06 - 2006.12)> • 국내 수치상대론 연구그룹 구축: KISTI: 3인(연구원 3), 한양대: 6인(교수 2, 연구원 1, 학생 3), 서울대: 5인(교수 2, 학생 3), 이화여대: 2인(교수 1, 학생 1), 군산대: 2인(교수 1, 학생 1), 인제대: 2인(교수 1, 학생 1), 서강대: 2인(연구원 1, 학생 1), 연세대: 1인(연구교수 1), 대진대: 1인(교수 1), 성균관대: 1인(연구교수 1), 천문연: 2인(연구원 2), 부산대: 1인(교수 1), 충남대: 1인(학생 1) 등 총 29명 (교수 11 + 연구원 7 + 학생 11) • 국내 수치상대론 연구의 활성화 및 안정화

  25. IV. Conclusion • In 2005 a break through occurred in binary black hole merger simulations. • Lots of work on binary BH systems followed afterward. • Many things remain to be understood though. • We speculated several topics with which Korean NR group may create its identity.

  26. After a long journey/struggling/waiting, we are at the stage of performing numerical simulations for some important topics this year 2007 now!

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