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Moment of Inertia of Neutron Star Crust Calculations vs. Glitches Observations

Moment of Inertia of Neutron Star Crust Calculations vs. Glitches Observations. Joanna Porębska Jagiellonian University – prof. Marek Kutschera & Nuclear Physics Institute (Polish Academy of Sciences) - collaboration with dr Sebastian Kubis, Cracow

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Moment of Inertia of Neutron Star Crust Calculations vs. Glitches Observations

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  1. Moment of Inertia of Neutron Star CrustCalculations vs. Glitches Observations Joanna Porębska Jagiellonian University – prof. Marek Kutschera & Nuclear Physics Institute (Polish Academy of Sciences) - collaboration with dr Sebastian Kubis, Cracow Dense Matter in HIC and Astrophysics, Dubna, 18.07.2008

  2. General structure of NS crust core

  3. Equations of Internal Structure 1)Tolman-Oppenheimer-Volkoff (TOV), rSch~4km → GR 2) mass=f(r) 3) Equation of State (EoS)

  4. EoS… in more details • only some analytical solutions • energy density (APR model) • energy per particle (nucleon) • derivatives of E,ε • masses

  5. EoS… density & pressure • density and pressure - full expressions • leptons

  6. Neutrality & β equilibrium • β equilibrium • electrical neutrality

  7. Compressibility K • stability considerations • V(n) - isoscalar potential • Es(n) – symmetry energy corresponding to the interactions isovector channel

  8. EoS again... two regimes • APR - Akmal, Pandharipande & Ravenhall (npe) • SLy - Skyrme, Lion SLy APR nlimit 0.01 ncc 0.08 nsat 0.16 nmax ~15 nsat n baryon density low density high density saturation of nuclear interactions

  9. Calculations • the fourh-order Runge-Kutta integration method (rk4) • output: • Moment of Inertia (Pethick, Ravenhall formulae) • Results…

  10. Glitches staff • What are they…? Glitch - sudden spin-up of pulsar produced by angular momentum transfer from the superfluid component of the stellar interior to the normal crust • What do they say about crust Moment of Inertia? … frequency jump spin-down rate jump

  11. Icrust from glitches • Ic - solid crust + tightly coupled rest (90% of all the star) • Ires - angular mom. reservoir • A - pulsar activity parameter • G - coupling parameter – minimum fraction of the star mom. of in. that stores angular momentum and imparts it to the crust in glitches • Alpar ’93 >2.4% , Datta&Alpar ’93 >3.4% for 1.4MΘ

  12. Conclusions.. • Hybrid approach (calculative-observational) • Verification/falsification • Quite nice confirmation.. • Still under construction • Considerations.. to be continued

  13. References • M.Camenzind, Compact Objects in Astrophysics (WD, NS & BH) (Springer-Verlag, Berlin Heidelberg, 2007) • N.K.Glendenning, Compact Stars: Nuclear Physics, Particle Physics and GR (Springer-Verlag, New York, 1997) • P.Haensel , A.Y.Potekhin, D.G.Yakovlev, Neutron Stars 1: Equation of State and Structure (Springer, 2007) • S.Kubis, Phys. Rev. C 76, 025801(2007) • C.P.Lorenz, D.G.Ravenhall, C.J.Pethick Phys. Rev. Lett. 70, 4 (1993) • B.Link, R.I.Epstein, J.M.Lattimer, Phys. Rev. Lett. 83, 17 (1999) • D.G.Ravenhall, C.J.Pethick, ApJ 424:846-851 (1994)

  14. Dziękuję bardzo Thank you

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