4U 1909+07：一颗隐藏得很好的珍珠（Conf. Proc.）
4U 1909+07: a well-hidden pearl (Conf. Proc.)
摘要：
本文首次用INTEGRAL和RXTE对大质量X射线双星4U 1909+07进行了详细的光谱和时间分析。4U 1909+07在ISGRI中被探测到，平均速度为2.4cps，但耀斑速度高达~ 50 cps。系统显示脉冲周期为605 s，但我们发现周期在此值附近不规则地变化。脉冲轮廓是非常依赖于能量的：虽然它在低能量下显示出双峰结构，但次级脉冲随着能量的增加而迅速减小，并且在20 keV以上，仅初级脉冲可见。PCA、HEXTE和ISGRI之间的这种演变是一致的。我们发现，相位平均光谱可以很好地符合光吸收功率定律，在高能量和黑体组件的截止。为了研究这种奇特的脉冲轮廓，我们进行了相位分辨光谱分析。我们发现，截止能量的变化是必需的，以适应不同的脉冲相位的变化的频谱。
英文摘要：
We present the first detailed spectral and timing analysis of the High Mass X-ray Binary (HMXB) 4U 1909+07 with INTEGRAL and RXTE. 4U 1909+07 is detected with an average of 2.4cps in ISGRI, but shows flares up to ~50cps. The system shows a pulse period of 605s, but we found that the period changes erratically around this value. The pulse profile is extremely energy dependent: while it shows a double peaked structure at low energies, the secondary pulse decreases rapidly with increasing energy and above 20keV only the primary pulse is visible. This evolution is consistent between PCA, HEXTE and ISGRI. We find that the phase averaged spectrum can be well fitted with a photoabsorbed power law with a cutoff at high energies and a blackbody component. To investigate the peculiar pulse profile, we performed phase resolved spectral analysis. We find that a change in the cutoff energy is required to fit the changing spectrum of the different pulse phases.
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