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Magnetic disk precession model for mHz QPO in 4U 1626-67

Magnetic disk precession model for mHz QPO in 4U 1626-67. Zhangzhen 2009.01.06. outlines. Background Theory Calculations Applications. background. Idea of MSPM (magnetic disk precession model). UV/optical: local disk normal vector and the line-of-sight change during precession

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Magnetic disk precession model for mHz QPO in 4U 1626-67

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  1. Magnetic disk precession model for mHz QPO in 4U 1626-67 Zhangzhen 2009.01.06

  2. outlines • Background • Theory • Calculations • Applications

  3. background

  4. Idea of MSPM(magnetic disk precession model) • UV/optical: local disk normal vector and the line-of-sight change during precession • The flux of reprocessed UV/optical disk emission visible along our sight also varies as the angle between the reprocessing geometry evolves • Occulation/obscuration of the radiation from the central NS and magnetosphere by the precessing inner disk • the global precession frequency driven by the magnetic torques

  5. Model

  6. Diamagnetic disk • Surface current • The torque per unit area • Precession frequency

  7. Magnetic threaded disk • Differencial rotation • Surface current • The torque per unit area • The warping rate

  8. Dynamical warp equation • Cartesian coordinates • The unit normal vector •  • The warp equation

  9. calculation • Power-law disk models: • Middle region solution of the -disk zero torque at the inner edge of the disk and power-law disk with

  10. Numerical results

  11. Mode eigenvalue and instability • A

  12. application • 4U 1626-67 • Her X-1:12 mHz QPO consistent with disk precession (Moon & Eikenberry 2001b) • LMC: 0.65-1.35 mHz

  13. summary • Dynamics of misaligned rotators •  precession torque • global eigenmold • magnetic disk precession model

  14. reference • arXiv: astro-ph/9904110v3 • arXiv:astro-ph/0109049v3

  15. thanks

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