标题： GRS 1915+105中与0.5-10 Hz准周期振荡相关的相位滞后变化 显示英文标题

标题： Phase lag variability associated with the 0.5-10 Hz QPO in GRS 1915+105

摘要： 我们利用 Rossi X 射线时变探测器的数据，测量了软光子（2-5 keV）和硬光子（5-13 keV）之间的滞后，并研究了超光速黑洞候选体 GRS 1915+105 在低流量状态下的非周期性变化。 功率密度谱显示出准周期振荡（QPO），其频率随计数率的增加而增加，并在 0.6-8 Hz 的频率范围内变化。 首次报告了 QPO 频率与相位滞后谱之间的相关性。 这种相关性在相位滞后连续谱和 QPO 频率处的相位滞后中均被发现。 我们发现，随着 QPO 频率向更高值移动，相位滞后从正值变为负值。 滞后绝对值始终随光子能量增加。 负（软）滞后与较软的能量谱相关联，而正（硬）滞后则出现在源较硬时。 我们描述了一种可能的情景，可以解释滞后符号的变化。 显示英文摘要

摘要： We have used Rossi X-ray Timing Explorer data to measure the lags between soft (2-5 keV) and hard (5-13 keV) photons and to study the aperiodic variability of the superluminal black hole candidate GRS 1915+105 during low-flux states. The power density spectra exhibit quasi-periodic oscillations (QPO) whose frequency increases with increasing count rate and varies in the frequency range 0.6-8 Hz. A correlation between the QPO frequency and the phase lag spectra is reported for the first time. This correlation is found for both the phase lag continuum and the phase lag at the QPO frequency. We find that as the QPO frequency moves to higher values the phase lags reverse sign from positive to negative. The absolute value of the lag always increases with photon energy. The negative (soft) lags are associated with a softer energy spectrum, whereas the positive (hard) lags are seen when the source is harder. We describe a possible scenario that may account for the change in the sign of the lags.