A spectral study of the persistent X-ray flux from 4U/MXB 1636-53.
van Paradijs, J.; Lewin, W. H. G.; Vacca, W. D.; Sztajno, M.; Truemper, J.; Smith, A.
United States, Germany, Netherlands
Abstract
The authors present a spectral analysis of the persistent X-ray flux from the X-ray burst source 4U/MXB 1636-53, which was continuously observed with EXOSAT for about 25 h in May 1984. They find that no standard one-component spectral model provides an acceptable representation of all the data. However, almost all "complex one-component" and "two-component" models do accurately fit the data. A blackbody plus a "multicolor" disk spectrum does not fit the data. In addition, it is found that some "two-component" spectral models can be fitted to the data with more than one set of different parameter values. Based on these results it is suggested that the various physical scenarios that have been proposed to interpret "two-component" spectra of low-mass X-ray binaries may be based on mathematical parameterizations which may not provide unique representations of the data. If this is the case, the reported "two-component" mathematical fits may not have any true physical significance.