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Importance of Compton scattering on X-ray spectra of Millisecond Pulsars and Intermediate Polars

Importance of Compton scattering on X-ray spectra of Millisecond Pulsars and Intermediate Polars. (Tuebingen University, Kazan State University). V . Suleimanov. In collaboration with. J. Poutanen (Oulu University) M. Falanga (SEA - Saclay). Millisecond Pulsars

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Importance of Compton scattering on X-ray spectra of Millisecond Pulsars and Intermediate Polars

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  1. Importance of Compton scattering on X-ray spectra of Millisecond Pulsars and Intermediate Polars (Tuebingen University, Kazan State University) V. Suleimanov In collaboration with J. Poutanen (Oulu University) M. Falanga (SEA - Saclay)

  2. Millisecond Pulsars LMXB, νspin(NS) ~ 200 – 700 Hz, Porb ~ 40 min – 4.5 hours, B ~ 108 – 109 Gs Intermediate Polars (IPs) CV, P spin (WD) < P orb, B ~ 1 – 10 MGs AD disrupted by magnetic field at some radius RA (Alfven radius) R A is radius where P ram = P mag

  3. 10 keV 1 keV

  4. 1 keV 10 keV

  5. 1 keV 10 keV

  6. Method of WD mass estimations • Shock wave standing above WD surface • The kinetic energy of the infalling gas is converted to the thermal energy • There is a reliable mass-radius relation for WD (Nauenberg 1972) • Maximum temperature after the shock depends on WD mass only • The temperature can be obtained from the fitting of the observed X-ray spectrum by bremsstrahlung model

  7. Spectrum of IP TV Col obtained with the RXTE observatory. Crosses denote the PCA data, open circles – HEXTE data. Solid line show best fit model (see below).

  8. Previous investigations • First works Rotschild et al (1981) - idea Ishida (1991) – GINGA / LAC observations, isothermal post-shock region (PSR, or accretion column) • Detail model of PSR (non-isothermal) Aizu (1973), Wu et al (1994), Woelk & Beuermann (1996), Cropper et al. (1999) • WD mass determinations using non-isothermal models of PSR Cropper et al (1999) – GINGA / LAC (2-20 keV) Ramsay (2000) – RXTE / PCA (3-20 keV)

  9. The modelbased on Cropper et al (1999) • Mass continuity equation • The momentum equation • The energy equation • Ideal-gas law • The cooling rate • The cooling function from Sutherland & Dopita (1993)

  10. Is Compton scattering significant?

  11. Method: radiation transfer solving by short characteristic method with Compton scattering taking into consideration (redistribution functions method (Poutanen & Svensson 1996))

  12. Results (plane parallel approximation ):

  13. More detail:

  14. More detail:

  15. Conclusions • Work is not finished • It is necessary to improve the “accretion column” model for Millisecond Pulsars • Compton scattering is significant for high mass Intermediate Polars and it is necessary to take into account

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