标题： 类星体3C 279中软X射线过量的限制 显示英文标题

标题： Constraints on a soft X-ray excess in the quasar 3C 279

摘要： 我们展示了通过X射线卫星RXTE和ROSAT对类星体3C 279进行的为期三周的日常监测结果。 交叉相关分析未发现软X射线和硬X射线光变曲线之间存在任何时间延迟的证据，且在观测期间源没有显著的光谱变化。 没有证据支持存在软 excess，0.1-2 keV波段中任何此类成分的99%上限为总观测光度的25%（小于3×10^38 W）。 这个比例（但不是光度）明显小于在3C 273中观测到的软 excess 比例。 显示英文摘要

摘要： We present the results of a three-week daily monitoring campaign on the quasar 3C 279 by the X-ray satellites RXTE and ROSAT. A cross correlation provides no evidence for any time lag between the very similar soft and hard X-ray light curves, and the source shows no significant spectral variability over the observing period. There is no evidence to support the presence of a soft excess, with a 99 per cent upper limit on any such component of 25 per cent of the total observed luminosity in the 0.1-2 keV band (< 3 x 10^38 W). This fraction (but not the luminosity) is significantly less than that of the soft excess observed in 3C 273.