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Magnetic Field Decay and Core Temperature of Magnetars, Normal and MS pulsars

Magnetic Field Decay and Core Temperature of Magnetars, Normal and MS pulsars. Shuang-Nan Zhang 张双南 1 Yi Xie 谢祎 2 1. Institute of High Energy Physics 2. National Astronomical Observatories of China. Evolutionary study of pulsars on p-pdot diagram. B decay required?. Han, J.L, 1997, A&A.

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Magnetic Field Decay and Core Temperature of Magnetars, Normal and MS pulsars

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  1. Magnetic Field Decay and Core Temperature of Magnetars, Normal and MS pulsars Shuang-Nan Zhang 张双南1 Yi Xie 谢祎2 1. Institute of High Energy Physics 2. National Astronomical Observatories of China

  2. Evolutionary study of pulsars on p-pdot diagram B decay required? Han, J.L, 1997, A&A

  3. Indirect Evidence for B decay? Han, J.L. (1997): power-law decay with “gene”: t0~B0 dependence

  4. Direct Evidence for B Decay Magnetars do not cross death line: normal radio pulsar mechanism works here? Consistent with recent detection of radio magnetars (talks by Manchester and Yuan in this meeting). magnetars Normal pulsars Best fits ms pulsars

  5. P-Pdot or B-Age? Pdot P Derived quantities using B-dipole radiation model (OK if not overwhelmed by pulsar wind loss), but direct comparison with B-decay model. Direct observables: But all tracks calculated using B-dipole radiation model, and indirect comparison with B-decay model.

  6. Inclination angle decay? • Then the observed B-decay may be in fact an illusion of inclination angle decay (Faucher-Giguère & Kaspi 2006; Weltevrede & Johnston 2008). • However, B-decay by 100 times for each kind of pulsars is difficult for inclination angle decay alone. • A better and more physical model required. Magnetic-Dipole radiation model:

  7. B Decay Model: Heyl & Kulkarni, 1998, ApJL The dominant term

  8. ~ Constant Core Temperatures of NSs magnetars normal pulsars ms pulsars

  9. All observed P and Pdot paired randomly All observed P Best fits of real pulsars All observed Pdot General trend of the observed distributions!

  10. Each class of observed P and Pdot paired randomly Model for real pulsars Very similar to the observed distributions!

  11. Completely simulated data: Gaussian distributions Input parameters Model for real pulsars Still very similar to the observed distributions!

  12. Completely simulated data: Not a surprise! Model for real pulsars B-Dipole radiation: Simulated data follow model precisely! For each type of pulsars P=const  Ambipolar B-Decay model (T=const):

  13. Why is the Pdot so small for all pulsars? • B-dipole radiation  • But why the observed Pdot is so small? • Ambipolar diffusion B-decay with constant core temperature  •  P~constant  Pdot must be very small! • This is a natural prediction of the above ambipolar diffusion B-decay model.

  14. Evidence for Hot Magnetars

  15. Evidence for Equilibrium between Heating & Cooling? ?

  16. Summary and Open Questions • No magnetar cross the pulsar’s death line • Normal pulsar radiation mechanism? • All NSs show clear evidence for B-deday • Agrees with ~constant Tcore ambipolar diffusion B-decay model well • Heating by B-decay energy and NS cooling by neutrino and emission in ~equilibrium for all pulsars? • The model naturally predicts very small Pdot as observed • Core temperature: Magnetars 2x108 K, Normal pulsars 2x107 K, ms pulsars 1x105 K • Different populations at birth?

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