Slim accretion disk model

This is an X-ray spectral model from optically-thick Advection Dominant Accretion Flow, often called "slim disk", which is expected when the mass accretion rate is very high (Kawaguchi 2003). The model spectra were calculated by Dr. Toshihiro Kawaguchi (kawaguti AT kusastro.kyoto-u.ac.jp) and the FITS conversion was made by Drs. Ken Ebisawa (ebisawa AT isas.jaxa.jp) and Takashi Okajima (okajima AT milkyway.gsfc.nasa.gov). This model was used in Vierdayanti et al. (2006) and Okajima et al (2006) to model X-ray spectra from Ultraluminous X-ray sources (ULXs).

Seven different spectral models are available in the FITS table model with the following different assumptions.

Model ID

  • 1. standard disk + local Blackbody [BB] emission
  • 2. slim disk + local BB
  • 3. slim disk + modified BB
  • 4. slim disk + comptonized local spectrum
  • 5. slim disk + local BB + relativistic effects
  • 6. slim disk + modified BB + relativistic effects
  • 7. slim disk + comptonized local spectrum + relativistic effects

The relativistic effects include gravitational redshift and transverse Doppler effect in the Schwarzchild metric.

In addition to the model ID, which is the fourth parameter, there are three free parameters besides normalization;

  • - mass of the central object (M) in solar mass unit (1-1000 Msun),
  • - accretion rate (Mdot) in the unit of Ledd/c^2, where Ledd is the Eddington luminosity and c is the light velocity (1-1000 Ledd/c^2),
  • - viscosity (alpha, 0.01-1)

Unit of the normalization is (10kpc/d)^2, where d is the distance in kpc.

References:
Kawaguchi, T. 2003, ApJ, 593, 69
Vierdayanti, K., Mineshige, S., Ebisawa, K. & Kawaguchi, T. 2006, PASJ, in press
Okajima, T., Ebisawa, K., & Kawaguchi, T., 2006, ApJ, in press

The table model file is available in gzipped format as kawaguchi2003.fits.gz.


Keith Arnaud, Lab. for High Energy Astrophysics, NASA/Goddard Space Flight Center

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