X射线选择类星体的一些性质

本文对109个X射线选择的类星体和114个射电及光学选择的类星体进行统计分析.发现在它们的红移、光学光度以及平均光学-X射线谱指数的直方分布图上, X射线选择类星体统计上都分布在这些参数图的低端.在所有样品的单色X射线光度l_X与单色光学光度l_O的关系图上, X射线选择类星体绝大部分处在光学暗的低光度区域.若以lglo=31.2erg/s·Hz为分界点, 可把光学光度划分为光学亮和暗两个区域, 则发现射电及光学选择类星体在图中光学亮区内的斜率b=0.64, 在光学暗区内的斜率b=0.95, 而X射线选择类星体的b仅为0.78, 因而暗示出它们可能是类星体现象中的一个次型. 

Some Properties of X-ray Selected Quasars

Statistical analysis for 109 X-ray selected quasars as well as 114 radio and optically selected quasars ds carried out in this paper. On the histograms of their redshift, optical luminosity and average optical X-ray spectral index, it is found that X-ray selected quasars are distributed at the low ends of plots of these parameters. On the plot of the monochromatic X-ray luminosity against the monochromatic optical luminosity l0 for all samples, most of the X-ray selected quasars are situated in'optically-faint regions of low luminosity. If we take lglo=31.2erg/s·Hz as a line of demarcation, and divide the optical luminosity into optically-bright and optically-faint regions, it is found that the radio and optically selected quasars have a slope of b=0.64 in the optically-bright region on this plot, and 6=0.95 in the optically-faint region, while the value of b of the X-ray selected quasars is only 0.78, thus implying that they may be a subtype of quasar phenomenon. Finally the factors affecting b are discussed briefly.