Spectral and Timing Studies of Cyg X-1 in the Low/Hard State with Suzaku
Spectral and Timing Studies of Cyg X-1 in the Low/Hard State with Suzaku
复制标题
DOI：
10.1093/pasj/63.sp3.s771
复制
发表时间：
2011-07
影响因子：
2.3
通讯作者：
S. Torii;S. Yamada;K. Makishima;Soki Sakurai;K. Nakazawa;H. Noda;C. Done;H. Takahashi;P. Gandhi
中科院分区：
文献类型：
--
作者：
S. Torii;S. Yamada;K. Makishima;Soki Sakurai;K. Nakazawa;H. Noda;C. Done;H. Takahashi;P. Gandhi
摘要2005 - 2009年，利用朱雀卫星对天鹅座X-1进行了25次观测，总曝光量为446 kS。在所有的观测中，源都是在低/硬状态下被发现的，而RXTE机载的全天监视器的1.5-12.0 keV计数率变化了10.3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材料的反射进行了拟合。随着软X射线强度的增加，康普顿参数从1.0减小到0.6，而反射立体角增加了约30%。还进行了10 −3 -10 Hz频率范围内的时序分析。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10 −3 - 10 −2 Hz范围内积分的分数硬X射线变化则减少了0.05倍。60- 200 keV波段的信号通常比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通过假设质量吸积率的增加导致康普顿化热日冕收缩，而光学厚盘侵入其中更深处来一致地解释。关键词：黑洞物理-吸积-恒星：个体（天鹅座X-1）-X射线：双星1
AbstractFrom 2005 to 2009, 25 observations of Cyg X-1 were performed with Suzaku, achiev-ing a total exposure of 446 ks. In all observations, the source was found in the low/hardstate, while the 1.5–12.0 keV count rate of the All-Sky Monitor onboard RXTE varied bya factor of ∼ 3. In each observation, the 10–60 keV HXD-PIN spectrum and the 60–400keV HXD-GSO spectrum were fitted successfully by a thermal Comptonization model plusreflection by a thick neutral material. As the soft X-ray intensity increased, the Comptony-parameter was found to decrease from 1.0 to 0.6, while the solid angle of reflection toincrease by ∼ 30%. Also conducted was timing analysis over a frequency range of 10 −3 –10 Hz. As the source became brighter in soft X-rays, the characteristic frequency of hardX-ray variation increased from 0.03 to 0.3 Hz, while the fractional hard X-ray variationintegrated over 10 −3 –10 −2 Hz decreased by a factor of ∼ 5. The signals in the 60–200keV band were generally found to vary on shorter time scales than those in the 10–60 keVband. These spectral and timing results can be consistently interpreted by presuming thatincreases in the mass accretion rate cause the Comptonizing hot corona to shrink, while theoptically-thick disk to intrude deeper therein.Key words: black hole physics — accretion — stars: individual (Cygnus X -1)—X-ray:binaries1