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Neutron Star Equation of States

GWWG@Kunsan. Neutron Star Equation of States. Chang-Hwan Lee @. Hot Issues in Astro-Hadron Physics. Heavy Ion Collision. RHIC. T. Hadrons. K bound system. Neutron Star. Density . Maximum Mass of Neutron Stars.

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Neutron Star Equation of States

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  1. GWWG@Kunsan Neutron Star Equation of States Chang-Hwan Lee @

  2. Hot Issues in Astro-Hadron Physics Heavy Ion Collision RHIC T Hadrons K bound system Neutron Star Density

  3. Maximum Mass of Neutron Stars • Standard Nuclear Physics : 2 - 2.5 Msun Binding energy at saturation density: -16 MeV at normal matter density Symmetry energy (iso-spin asymmetry): proton vs neutron : 30 MeV • Exotic States : 1.5 - 2 Msun pion condensation kaon condensation strange quark star…….

  4. Neutron Star vs Nuclear Star ? Chemical Potential n -> p + e- Nuclear Star

  5. Kaons in Nuclear Star Attraction between quark & anti-quark K- ( u s) : N (uud,udd) n, p, e n, p, e => n, p, K- Nuclear Star Kaon Condensation in NS

  6. Why exotic states with strange quark ? • proton, neutron: u, d quarks • chemical potential is high enough to generate heavier strange quarks in the system • By introducing strange quark, we have one more degrees of freedom, can reduce the system energy • In what form ? Kaon, Hyperons ……

  7. Kaon Condensation in Dense Matter

  8. Astrophysical Implications Neutron Star Neutrinos Reduce Pressure Formation of low mass Black Hole

  9. Maximum Mass of NS Black Holes Neutron Stars

  10. Smoking guns for Strangeness SN 1987A • Formation of 1.5 Msun NS : theoretically confirmed by neutrino detection (2002 Nobel prize) • No evidence of NS, yet. (e.g., no Pulsar signal) • NS went into Small Mass Black Hole (by cooling & accretion) !! Masses of Radio Pulsars < 1.5 Msun

  11. 1.5

  12. Kaon Production in Heavy Ion Collisions Can we test “Dropping K- Mass” on earth ?

  13. Kaon Effective Mass K+ us q-q repulsion q-q attraction us K-

  14. Kaon Production in Heavy Ion Collision supports Dropping K- mass !

  15. new developments: Kaonic Nuclear Bound States • Is kaon-nuclear attraction is strong enough to make kaon condensation ? Yamazaki et al. (2003)

  16. Antisymmetric Molecular Dynamics Method Isovector Deformation Dote et al. 2002 3He 3HeK-

  17. PLB 597 (2004) 263 Total binding energy : 194 MeV from K-ppn Mass = 3117 MeV, width < 21 MeV

  18. deep discrete bound states:with binding energy ~ 100 MeV Strong in-medium KN interactions. Precursor to kaon condensation. Kaonic Nuclei - Mini Strange Star Very strong K--p attraction

  19. Neutron Stars Recent Observations • Isolated Single Neutron Stars • Binary Neutron Stars Q) Is kaon condensation still plausible ?

  20. Isolated Single Neutron Stars J. Drake, KIAS-APCTP conference, 2003

  21. Chandra LETGS 0th Order ESO VLT RX J1856.5-3754 in Visible Light and X-rays

  22. RX J1856.5-3754 in Chandra Observation No pulsations: Limit < 4% - emission from whole of stellar surface ? IF object radiates as blackbody, R too small for neutron star… Rinf=4-8.2 km Drake et al (2002) suggested possible strange quark star interpretation Teff=60 eV Rinf=3.8-8.2 km NH=1x1020 cm2

  23. They just fit into the Grand Canyon…

  24. Argument for a conventional NS Walter & Lattimer (2002) • Walter & Lattimer (2002) with HST parallax of 117 pc get Rinf=12-26 km with: • Two-component blackbody BUT no pulsations observed • Si or Fe model BUT no spectral features observed • Is RX J1856.5-3754 a Quark Star? • Until we can better understand the surface character, interpretation is open • So, Neutron Star with kaon condensation is still open possibility !

  25. Binary Neutron Stars J0737-3039: 1.337 Msun & 1.290 Msun “Most recent observation of binary neutron star is also consistent with the limit suggested by kaon condensation.” [nautre, 2003] astro-ph/0411796 PSR J1756-2251: 1.4 Msun & 1.2 Msun

  26. Q) X-ray Binary [Vela X-1] > 2 Msun ? “The best estimate of the mass of Vela X-1 is 1.86 Msun. Unfortunately, no firm constraints on the equation of state are possible since systematic deviations in the radial-velocity curve do not allow us to exclude a mass around 1.4 Msun as found for other neutron stars.” [Barziv et al. 2001]

  27. Summary of works on Kaon Condensation in NS Mass of Iron Core • < 1.5 Msun : NS • 1.5-1.8 Msun : NS => BH (by cooling/accretion) • > 1.8 Msun : BH There are much more Black Holes than we thought !!

  28. Gravitation Wave from Binary Neutron Star Theory vs Observation: Effect of Gravitational Wave Radiation 1993 Nobel PrizeHulse & Taylor

  29. NS + LMBH Binaries as GW source • In usual scenario of double pulsar formation => first born NS can go into Low-Mass BH (1.5-2.5 Msun) by accretion • “NS+LMBH” is 10 times more dominant than “NS+NS” system. • There may many more GW sources than originally expected based on Hulse & Taylor binary pulsar. • “NS+LMBH” system may increase LIGO detection rate by factor of 20.

  30. Conclusions • Recent works on kaon experiments support strong kaon-nucleon attraction. • Kaon condensation in neutron stars is still plausible after various recent observations. • “LMBH+NS” binaries can increase LIGO detection rate by factor 20.

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