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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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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 • 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…….
Neutron Star vs Nuclear Star ? Chemical Potential n -> p + e- Nuclear Star
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
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 ……
Astrophysical Implications Neutron Star Neutrinos Reduce Pressure Formation of low mass Black Hole
Maximum Mass of NS Black Holes Neutron Stars
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
Kaon Production in Heavy Ion Collisions Can we test “Dropping K- Mass” on earth ?
Kaon Effective Mass K+ us q-q repulsion q-q attraction us K-
Kaon Production in Heavy Ion Collision supports Dropping K- mass !
new developments: Kaonic Nuclear Bound States • Is kaon-nuclear attraction is strong enough to make kaon condensation ? Yamazaki et al. (2003)
Antisymmetric Molecular Dynamics Method Isovector Deformation Dote et al. 2002 3He 3HeK-
PLB 597 (2004) 263 Total binding energy : 194 MeV from K-ppn Mass = 3117 MeV, width < 21 MeV
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
Neutron Stars Recent Observations • Isolated Single Neutron Stars • Binary Neutron Stars Q) Is kaon condensation still plausible ?
Isolated Single Neutron Stars J. Drake, KIAS-APCTP conference, 2003
Chandra LETGS 0th Order ESO VLT RX J1856.5-3754 in Visible Light and X-rays
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
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 !
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
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]
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 !!
Gravitation Wave from Binary Neutron Star Theory vs Observation: Effect of Gravitational Wave Radiation 1993 Nobel PrizeHulse & Taylor
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.
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.