Abstract
We present spectral observations of the low-mass X-ray binary source X1820-303 obtained with the GINGA Large Area Counter. Two two-component spectral models are found to provide good fits to the data; the superposition of a bremsstrahlung component and a blackbody, or a power-law with exponential cut-off and a blackbody. In both cases, inclusion of an iron line at 6.7 KeV improves the fits. After considering the importance of Comptonization for the spectral and temporal behaviour, we selected the power-law and blackbody model. The model requires a scattering cloud surrounding the neutron star, with a Thomson optical depth of ~7.
By studying the spectrum as the source intensity varies, we find that the blackbody and iron-line fluxes both show an increase by a factor of ~3, while the power-law component only shows a ~20% increase. This clearly shows that the iron-line and blackbody emission regions are related, and we suggest that they both originate from the inner parts of the accretion disk.
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© 1991 Springer-Verlag
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Kellett, B.J., Ercan, E.N., Cruise, A.M. (1991). GINGA observation of X1820-303 and its iron-line emission. In: Treves, A., Perola, G.C., Stella, L. (eds) Iron Line Diagnostics in X-ray Sources. Lecture Notes in Physics, vol 385. Springer, Berlin, Heidelberg. https://doi.org/10.1007/BFb0031286
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DOI: https://doi.org/10.1007/BFb0031286
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