标题： 与GRS 1915+105中1-10 Hz QPO相关的相位滞后变化 显示英文标题

标题： Phase lag variability associated with the 1-10 Hz QPO in GRS 1915+105

摘要： 我们使用Rossi X射线时变探测器的数据，测量了软(2-5 keV)和硬(5-13 keV)光子之间的滞后，并研究了低通量状态下超光速黑洞候选体GRS 1915+105的非周期性变化。 功率密度谱表现出准周期振荡(QPO)，其频率随着计数率的增加而增加，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。 这种相关性既适用于相位滞后连续体，也适用于QPO频率处的相位滞后，尽管相关性的形状略有不同。 我们发现，当QPO频率向更高值移动时，相位滞后从正号变为负号。 滞后的绝对值始终随光子能量的增加而增加。 负的(软)滞后与更软的能量谱有关，而正的(硬)滞后则在源更硬时出现。 我们描述了两种可能解释滞后符号变化的场景。 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, although the shape of the correlations is somewhat different. 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 two different scenarios that may account for the change in the sign of the lags.