The X and UV emissions of active galactic nuclei

A statistical analysis of 87 optical selected quasars and 30 type I Seyfert galaxies is carried out in this paper. Using a quasi-Monte-Carlo method, the relation between the 2 keV monochromatic X-ray luminosity 1_X and ～2500A monochromatic ultraviolet luminosity is calculated and the result is: 1_x ∝ 1₀^bp, b = 0.93 ± 0.18 when the accretion rate ? _cr, and b = 0.28 ± 0.18 when > _cr.A detailed semi-quantitative physical discussion of our results ruled out many available radiative mechanisms. We conclude that the most plausible dominant radiation in the band from 2500A UV to 2 keV soft X-ray is non-thermal synchrotron radiation. We discuss that when the accretion rate is growing, most of the X radiation is dragged into the black hole (the dragging effect). This is the main reason why the X-ray luminosity increases much more slowly with M than does the UV luminosity.Finally, in the context of pure luminosity evolution, we have obtained that 1_x evolves more slowly than does 1_0p.