The Cross Spectra of Circinus X-1: Evolution of Time Lags
The Cross Spectra of Circinus X-1: Evolution of Time Lags
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DOI：
10.1086/321460
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发表时间：
2001-03
期刊：
影响因子：
--
通讯作者：
J. Qu;W. Yu;T. Li
中科院分区：
文献类型：
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作者：
J. Qu;W. Yu;T. Li
早期的工作表明，Cir X-1的X射线硬度-强度图中的轨道对应于其色-色图中的Z轨道。本文利用RXTE/PCA数据研究了Cir X-1在硬度-强度图上不同区域的互谱。比较了Cir X-1在1.8-5.1 keV和5.1-13.1 keV两个能量带的光变曲线，发现Cir X-1在水平分支上表现出硬时滞，在正常分支和耀斑分支上表现出软时滞。这表明Cir X-1在水平分支上与GX 5-1和Cyg X-2相似，但在正常分支上与它们不同。我们简要地讨论了康普顿化模型的背景下的时间滞后的机制。
Earlier work showed that the track in the X-ray hardness-intensity diagram of Cir X-1 corresponds to a Z track in its color-color diagram. In this paper, we study the cross spectrum of Cir X-1 in different regions of the hardness-intensity diagram with RXTE/PCA data. Comparing the light curves of Cir X-1 for the energy band 1.8-5.1 keV with those for 5.1-13.1 keV, we find that Cir X-1 exhibits a hard time lag on the horizontal branch and a soft time lag on both the normal and the flaring branches. This indicates that Cir X-1 is similar to GX 5-1 and Cyg X-2 on the horizontal branch but is different from them on the normal branch. We briefly discuss the mechanism of the time lags in the context of Comptonization models.