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Realistic Calculations of Hyperon-Mixed Phase and Neutron Stars at Birth and at Evolved Stage

Research Project

Project/Area Number 11640245
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field 素粒子・核・宇宙線
Research InstitutionIwate University

Principal Investigator

TAKATSUKA Tatsuyuki  Faculty of Humanities and Social Sciences, Iwate University Professor, 人文社会科学部, 教授 (50043427)

Co-Investigator(Kenkyū-buntansha) YAMAMOTO Yasuo  Physica Section, Tsuru University, Professor, 文学部, 教授 (80124866)
NISHIZAKI Shigeru  Faculty of Humanities and Social Sciences, Iwate University Associate Professor, 人文社会科学部, 助教授 (60198455)
Project Period (FY) 1999 – 2000
Project Status Completed (Fiscal Year 2000)
Budget Amount *help
¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 2000: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1999: ¥1,300,000 (Direct Cost: ¥1,300,000)
KeywordsHyperon-Mixing / Effective YN and YY interactions / Neutron Stars / Hyperon Superfluidity / Neutron-Star Mass / Equation of State / ハイペロン有効質量
Research Abstract

(A) The effective ΛN and ΛΛ interactions applicable to the Y-mixing problem are constructed from the G-matrix calculations by paying particular attention to the use of YN and YY interactions compatible with hypernuclear data. Similarly, the effective Σ^-N and Σ^-Σ^- interactions are constructed.
(B) The Y-mixing problem in neutron star cores is investigated by an efffective interaction approach based on (A). It is found that ∧ and Σ^- begin to mix in neutron star matter at the total baryon density ρ〜3ρ_0 (ρ_0 being the nuclear density) and the mixing ratio y_Y increases with ρ, with hyperons becoming components comparable to nucleons (N) (e.g., y_Λ〜20%, y_Σ-〜15%, y_p〜15%, y_n〜50% at ρ=6ρ_0). Of particular interest is the fact that the Y-mixing effects soften the EOS dramatically and thereby the maximum mass M_<max> sustained by the EOS cannot exceed the observed mass M_<obs>=1.44M_<【of sun】> for PSR1913+16, leading to a serious problem contradicting observations. The mechanism of such a dramatic softening is analyzed, showing up the characterisics of Y-mixing effects.
(C) It is stressed that M_<max><M_<obs> is of special interest, suggesting the necessity of "Extra Repulsion" in hypernuclear systems. It is pointed out that such a repulsion as in the three- body force currently introduced in nuclear systems could be one of the candidates for "Extra Repulsion".
(D) The existence of Λ- and Σ^-- superfluids (and also Ξ^--superfluid) in neutron star cores is shown by using three kinds of YY interaction models. The limited density region for Λ-superfluid interestingly restricts the mass of neutron stars with the "hyperon cooling".

Report

(3 results)
  • 2000 Annual Research Report   Final Research Report Summary
  • 1999 Annual Research Report
  • Research Products

    (21 results)

All Other

All Publications (21 results)

  • [Publications] Tatsuyuki TAKATSUKA: "Hyperon Superfluidity in Neutron Star Cores"Advances in Quantum Many-Body Theory. Vol.3. 323-326 (2000)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2000 Final Research Report Summary
  • [Publications] Tatsuyuki TAKATSUKA: "Superfluidity of Λ-, Σ^--, Ξ^-- Hyperons in Neutron Star Cores"Few-Body Systems Suppl.. Vol.12. 108-113 (2000)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2000 Final Research Report Summary
  • [Publications] Tatsuyuki TAKATSUKA: "Λ-Hyperon Superfluidity in Neutron Stars and in Hyperonic Nuclear Matter"Strangeness Nuclear Physics (World Scientific). 337-346 (2000)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2000 Final Research Report Summary
  • [Publications] Yasuo YAMAMOTO: "Single-Particle Potential and Effective Masses of Hyperons in Hyperonic Nuclear Systems"Progress of Theoretical Physics. Vol.103. 981-1000 (2000)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2000 Final Research Report Summary
  • [Publications] Tatsuyuki TAKATSUKA: "The Possibility of Hyperon Superfluids in Neutron Star Cores"Progress of Theoretical Physics. Vol.105. 179-184 (2001)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2000 Final Research Report Summary
  • [Publications] Sigeru NISHIZAKI: "Effective YN and YY interactions and Hyperon-Mixing in Neutron Star Matter -YΞΛ case-"Progress of Theoretical Physics. Vol.105. (2001)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2000 Final Research Report Summary
  • [Publications] T.Takatsuka, S.Nishizaki, Y.Yamamoto, R.Tamagaki: "Hyperon Superfluidity in Neutron Star Cores"Advances in Quantum Many-Body Theory. Vol.3. 323-326 (2002)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2000 Final Research Report Summary
  • [Publications] T.Takatsuka, S.Nishizaki, Y.Yamamoto, R.Tamagaki: "Superfluidity of Λ-, Σ^--, Ξ^--Hyperons in Neutron Star Cores"Few-Body Systems Suppl. Vol.12. 108-113 (2002)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2000 Final Research Report Summary
  • [Publications] T.Takatsuka and R.Tamagaki: "Λ-Hyperon Superfluidity in Neutron Stars and in Hyperonic Nuclear Matter""Strangeness Nuclear Physics" (World Scientific). 337-346 (2000)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2000 Final Research Report Summary
  • [Publications] T.Yamamoto, S.Nishizaki, T.Takatsuka: "Single-Particle Potential and Effective Masses of Hyperons in Hyperonic Nuclear Systems"Progress of Theoretical Physics. Vol.103. 981-1000 (2000)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2000 Final Research Report Summary
  • [Publications] T.Takatsuka, S.Nishizaki, Y.Yamamoto, R.Tamagaki: "The Possibility of Hyperon Superfluids in Neutron Star Cores"Progress of Theoretical Physics. Vol.105. 179-184 (2001)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2000 Final Research Report Summary
  • [Publications] S.Nishizaki, Y.Yamamoto, T.Takatsuka: "Effective YN and YY interactions and Hyperon-Mixing in Neutron Star Matter -YΞΛ case-"Progress of Theoretical Physics. Vol.105. (2001)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2000 Final Research Report Summary
  • [Publications] Tatsuyuki TAKATSUKA: "Hyperon Superfluidity in Neutron Star Cores"Advances in Quantum Many-Body Theory. Vol.3. 323-326 (2000)

    • Related Report
      2000 Annual Research Report
  • [Publications] Tatsuyuki TAKATSUKA: "Superfluidity of Λ-,Σ^--,Ξ^--Hyperons in Neutron Star Cores"Few-Body Systems Suppl.. Vol.12. 108-113 (2000)

    • Related Report
      2000 Annual Research Report
  • [Publications] Tatsuyuki TAKATSUKA: "Λ-Hyperon Superfluidity in Neutron Stars and in Hyperonic Nuclear Matter"Strangeness Nuclear Physics(World Scientific). 337-346 (2000)

    • Related Report
      2000 Annual Research Report
  • [Publications] Yasuo YAMAMOTO: "Single-Particle Potential and Effective Masses of Hyperons in Hyperonic Nuclear Systems"Progress of Theoretical Physics. Vol.103,No.5. 981-1000 (2000)

    • Related Report
      2000 Annual Research Report
  • [Publications] Tatsuyuki TAKATSUKA: "The Possibility of Hyperon Superfluids in Neutron Star Cores"Progress of Theoretical Physics. Vol.105,No.1. 179-184 (2001)

    • Related Report
      2000 Annual Research Report
  • [Publications] Sigeru NISHIZAKI: "Effective YN and YY interactions and Hyperon-Mixing in Neutron Star Matter-YΞΛcase-"Progress of Theoretical Physics. Vol.105,No.4. (2001)

    • Related Report
      2000 Annual Research Report
  • [Publications] Tatsuyuki TAKATSUKA: "Baryonic 3P_2 Superfluidity under Charged-Pion Condensation with Δ Isobar"Progress of Theoretical Physics. Vol.101,No.5. 1043-1081 (1999)

    • Related Report
      1999 Annual Research Report
  • [Publications] Tatsuyuki TAKATSUKA: "Λ-Hyperon Superfluidity in Neutron Star Cores"Nuclear Physics A. (1999)

    • Related Report
      1999 Annual Research Report
  • [Publications] Tatsuyuki TAKATSUKA: "Superfluidity of Λ-Hyperons Admixed in Neutron Star Cores"Progress of Theoretical Physics. Vol.102,No.5. 1043-1048 (1999)

    • Related Report
      1999 Annual Research Report

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Published: 1999-04-01   Modified: 2016-04-21  

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