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X-ray photo-ionized bubble in the wind of vela X-1 pulsar supergiant companion

X-ray photo-ionized bubble in the wind of vela X-1 pulsar supergiant companion. ArXiv: 1208.1827v1 (2012.08.09) Jiri Krticka Jiri Kubat and JanSkalicky Reporter: cheng zhongqun. Outlines. CAK model for star winds

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X-ray photo-ionized bubble in the wind of vela X-1 pulsar supergiant companion

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  1. X-ray photo-ionized bubble in the wind of vela X-1 pulsar supergiant companion ArXiv: 1208.1827v1 (2012.08.09) Jiri Krticka Jiri Kubat and JanSkalicky Reporter: cheng zhongqun

  2. Outlines • CAK model for star winds • Influences of X-ray photo-ionization to star winds • Wind accretion of compact stars • Upper X-ray luminosity limit of wind accretion HMXRBs • Discussion and conclusions

  3. CAK model for star wind • The luminosity of stars can't exceed it's Eddington,but the star wind can be accelerated through ultraviolet resonance lines of ions like Si,C,S,and N...(Lucy&Solomon,1970) • Compare with large number of subordinate lines,force due to resonance lines is 100 times lesser (Castor,Abbott&Klein,1975)

  4. CAK model for star wind force multiplier:

  5. mass conservation: momentum balance: equation of state:

  6. CAK result for a O5 star:

  7. CAK results

  8. Vela X-1 binary system

  9. wind velocity: X-ray opacity per unit mass:

  10. Some simplifications to Vela X-1 system no wind clumping axis-symmetric system Only a two dimensions calculation (r, d) on the orbital plane

  11. Optical depth on orbital plane • Optical depth for 830 eV photons with certain luminosity • The X-rays can strongly penetrate the wind faces the NS.

  12. Wind velocity for different inclinations The wind velocity is apparently influenced when Wind even can't arrive the NS when

  13. Wind accretion of NS star In the frame of NS:

  14. For Vela X-1 binary system: when so wind can been accreted to NS only when which related to a X-ray luminosity:

  15. Two possible states for wind accretions • Strong X-ray sources like Vela: • Possible weak X-ray sources since wind acceleration has been strongly influenced by X-ray photo-ionization

  16. Limitation on maximum X-ray luminosity For vela system,a slightly lower wind mass-loss rate or a slightly stronger X-ray luminosity will leads to a deeper penetration of X-ray and significantly ionization state of wind,that imply a maximum luminosity of X-ray for a wind accretion HMXB system with given geometry parameters and wind mass-loss rate.

  17. . Assuming vela X-ray luminosity is the largest one , for other wind accretion HMXBs:

  18. Discussion and conclusions • Numerical calculation shows that X-ray photo-ionization can effectively influence the acceleration of star wind in Vela X-1 and lead to a stagnating wind flow between the NS and its companion • An upper limit to X-ray luminosity can get without disrupting the stellar wind in wind accretion HMXBs system with certain mass loss-rate and geometry parameters,this can get support from observations.

  19. The wind equations allow two types of solutions with different X-ray luminosities and wind velocities in the Vela X-1 or other systems. switching between the two solution states may responsible for the X-ray variabilities of HMXBs.

  20. Thanks!

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