Reporter: ZhangZhen 2010.05.10

1. Spin Evolution of Neutron Stars in OB/X-ray BinariesFan Zhang, Xiang-Dong Li, & Zhen-Ru Wang, 2004, CHJAA, 320, 334 Reporter: ZhangZhen 2010.05.10

2. outlines • Map of spin evolution • Details of each procedure • Calculation results

3. Overall map • Plausible histroy for such binary systems two massive main sequence stars supernova  NS (rotating rapidly) sleeping phase: NS spin down MS evolves ~ accreting matter  X-ray source

4. About energy loss • through a quai-static atomosphere (the equation of hydrostatic equlibirium) • at the base: NS transfer energy to it • the atomosphere dose not cool significantly and keep hot • the energy transfers outwards

5. case a: pulsar-like phase • New born NS: radio pulsar • Radiation strong enough to expel the wind material outside or • Magnetic dipole radiation makes the NS loss energy as well as the AM

6. the end of case a • energy loss  , decrease • gravitation become important  pressure gradients significant  case c • pulsar emission ineffective •  case b

7. case c: supersonic propeller phase • the NS can't accrete due to the centrifugal barrier • supersonic rotation distortion of the magnetospheric boundary interaction occurs at the interface • Energy loss: rotational energy

8. case d: subsonic propeller phase • the necessary for NS to accrete: the meterial outside the magnetosphere is able to cool • energy loss: rotational energy • via: vicosity  turbelent

9. case b: rapid rotator phase • Resemble to case c in: dissipation mechanism occurs at magnetosphere boundary • different in the surrounding atmosphere  the pressure is nearly constant  the gas is hot • end with

10. more details about case b • b1 b2 • paradox b1d b2c • magnetic plough the incoming plasma are almost totally obstructed outside the magnetosphere

11. Fan Zhang et al. 2004

15. Thanks