类星体色指数随红移的变化

Changes of QSO Color Indices with Redshift

本文讨论了类星体各光谱特征对其色指数的影响以及色指数随红移的变化．随着红移的增加，位于Ｌｙα发射线短波方向的各种吸收特征进入了可见光区，内禀的幂律谱和发射线强度的分布对类星体色指数及其弥散的影响将是次要的，各种吸收系统的作用将改变类星体色指数随红移变化的趋势，其中，Ｌｙｍａｎ系限吸收系统的影响最大。利用ＩＵＥ观测的类星体光谱求得色指数随红移的变化，对上述结果进行了验证。

We discuss the influences of various spectral features of QSO on its color indices.The intrinsic power law continuum and the strong emission lines dominate the color indices only for low redshift QSOs.With redshift over 2.2,the strong absorption shortward of Lyman alpha emission:Lyman alpha forest,damped Lyman alpha absorption lines,and Lyman Limit Systems (LLSs)become more and more important.At very high redshift,the LLSs dominate the color indices.The IUE archival spectra of QSOs are shifted to different redshift,and used to demonstrate the general behavior of QSO color indices as function of redshift.