标题： 明亮活动星系核中软X射线的起源 显示英文标题

标题： The origin of soft X-rays in luminous AGN

摘要： 我们预测类星体的紫外线峰值光谱会延伸到软X射线范围，呈陡峭的幂律。 对于射电明亮的类星体，光谱指数为 alpha_s ~ 1.7（S_nu = S_o nu^-alpha），而对于射电安静的类星体，它应该更陡一些，alpha_s >~ 1.7。 这一预测基于一个简单的场景，其中所有类星体，包括射电安静和射电明亮的，都被假定其喷流接近吸积盘。 软X射线是通过在（略微）光学厚的喷流基部对来自吸积盘的紫外光子进行未饱和的康普顿化产生的。 非热硬X射线则在下游进一步产生。 该情景要求（i）喷流的动能光度始终与紫外光度在同一数量级，并且（ii）非热辐射效率约为10%。 在射电安静的类星体中，喷流应具有约0.3c的速度和低马赫数，导致在中心秒差距内迅速准直并湍流物质卷入。 显示英文摘要

摘要： We predict that the UV bump spectrum of quasars extends into the soft X-ray range with a steep power law. For radio-louds, the spectral index is alpha_s ~ 1.7 (S_nu = S_o nu^-alpha), and for radio-quiets it should be somewhat steeper alpha_s >~ 1.7. The prediction is based on a simple scenario in which all quasars, radio-quiets and radio-louds, are assumed to have jets close to their accretion disks. Soft X-rays are produced via unsaturated Comptonization of UV photons from the disk in the (marginally) optically thick jet base. Nonthermal hard X-rays are produced further downstream. The scenario requires that (i) the jet kinetic luminosity is always of the same order as the UV luminosity and (ii) that the nonthermal radiative efficiency is ~ 10%. In radio-quiets, the jets should have speeds of ~ 0.3c and a low Mach number leading to rapid decollimation and turbulent mass entrainment within the central parsec.