过渡区的遮掩对吸积盘出射谱的影响

THE OCCULTING EFFECT OF THE TRANSITION REGION ON EMERGENT SPECTRA OF ACCRETION DISCS

对于外区几何厚、内区几何薄的吸积盘,从前者到后者有一个过渡区.本文计算了内区未被过渡区遮掩部分的辐射谱,并考虑了过渡区对内区辐射的反射,得出应观测到的吸积盘的出射谱.结果表明,当过渡区遮掩了吸积盘中央部分时,出射谱与稳恒吸积盘的标准谱有显著差别,对某些矮新星连续谱的解释可能起作用.

There may exist a transition region from the geometrically thick outer region to the geometrically thin inner region in an accretion disc. It would form a high wall which is opaque because of electron scattering. In this paper we consider the occultation of the inner region and the reflecting effect by the wall to get emergent continuous spectra of accretion discs. We come to the following conclusion. When the central portion of a disc is not occulted, the emergent spectra of the disc are consistent with the standard steady accretion disc spectra, so that the existence of the wall can be ignored. In the opposite case, the emergent spectra have indices prominently different from 1/3 in the intermediate frequency range. In particular, it is possible for the spectral index to have negative values. The results of this paper might play some role in the explanation of the continuous spectra of some dwarf novae.