标题： 超光相机观测到的黑洞X射线暂现源XTE J1118+480处于宁静态的情况 显示英文标题

标题： ULTRACAM observations of the black hole X-ray transient XTE J1118+480 in quiescence

摘要： 我们展示了使用ULTRACAM获得的宁静软X射线暂现源XTE J1118+480的高时间分辨率多色观测结果。双峰连续谱g'和i'波段光变曲线上叠加有快速耀发事件，这些耀发通常持续几分钟。光变曲线的功率密度谱可以用一个具有约2毫赫兹断频的破碎幂律模型来描述，或者用一个幂律模型加上一个约2毫赫兹的宽准周期振荡（QPO）。在细胞自动机的背景下，我们估计宁静的辐射主导流（ADAF）区域的大小约为10⁴史瓦西半径，与其他宁静黑洞X射线暂现源所观察到的结果相似，表明存在相同的物理机制。低/硬态和宁静态PDS之间的相似性表明光学和X射线变化可能具有相同的起源，最有可能来自ADAF附近/内部的区域。 显示英文摘要

摘要： We present high time-resolution multicolour observations of the quiescent soft X-ray transient XTE J1118+480 obtained with ULTRACAM. Superimposed on the double-humped continuum g' and i'-band lightcurves are rapid flare events which typically last a few minutes. The power density spectrum of the lightcurves can be described by a broken power-law model with a break frequency at ~2 mHz or a power-law model plus a broad quasi-periodic oscillation (QPO) at ~2 mHz. In the context of the cellular-automaton we estimate the size of the quiescent advection-dominated flow (ADAF) region to be ~10^4 Schwarzschild radii, similar to that observed in other quiescent black hole X-ray transients, suggesting the same underlying physics. The similarites between the low/hard and quiescent state PDS suggest a similar origin for the optical and X-ray variability, most likely from regions at/near the ADAF.