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arXiv 1107.3590astro-ph.HE
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低/硬态Cyg X-1的光谱和计时研究

Spectral and Timing Studies of Cyg X-1 in the Low/Hard State with Suzaku

Shunsuke Torii, Shin'ya Yamada, Kazuo Makishima, Soki Sakurai, Kazuhiro Nakazawa, Hirofumi Noda, Chris Done, Hiromitsu Takahashi, Poshak Gandhi

摘要:

从2005年到2009年,朱雀号对天鹅座X-1进行了25次观测,总曝光量为446 ks。在所有的观测中,源被发现在低/硬状态,而1.5- 12.0千电子伏的计数率的全天空监视器机载RXTE变化了约3倍。在每一次观测中,10- 60 keV的HXD-PIN谱和60- 400 keV的HXD-GSO谱都成功地用热康普顿化模型加上厚中性物质的反射进行了拟合。随着软X射线强度的增加,发现康普顿y参数从1.0减小到0.6,而反射的立体角增加约30%。还进行了0.001- 10 Hz频率范围内的定时分析。随着源在软X射线中变得更亮,硬X射线变化的特征频率从0.03 Hz增加到0.3 Hz,而在0.001- 0.01 Hz上积分的分数硬X射线变化减少了约5倍。一般发现60- 200 keV波段的信号比10- 60 keV波段的信号在更短的时间尺度上变化。这些光谱和时间的结果可以一致地解释,假设增加质量吸积率导致康普顿热日冕收缩,而光学厚盘侵入更深。

英文摘要:

From 2005 to 2009, 25 observations of Cyg X-1 were performed with Suzaku, achieving a total exposure of 446 ks. In all observations, the source was found in the low/hard state, while the 1.5--12.0 keV count rate of the All-Sky Monitor onboard RXTE varied by a factor of ~ 3. In each observation, the 10--60 keV HXD-PIN spectrum and the 60--400 keV HXD-GSO spectrum were fitted successfully by a thermal Comptonization model plus reflection by a thick neutral material. As the soft X-ray intensity increased, the Compton y-parameter was found to decrease from 1.0 to 0.6, while the solid angle of reflection to increase by ~ 30%. Also conducted was timing analysis over a frequency range of 0.001--10 Hz. As the source became brighter in soft X-rays, the characteristic frequency of hard X-ray variation increased from 0.03 to 0.3 Hz, while the fractional hard X-ray variation integrated over 0.001--0.01 Hz decreased by a factor of ~ 5. The signals in the 60--200 keV band were generally found to vary on shorter time scales than those in the 10--60 keV band. These spectral and timing results can be consistently interpreted by presuming that increases in the mass accretion rate cause the Comptonizing hot corona to shrink, while the optically-thick disk to intrude deeper therein.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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