Unified X-ray spectral and timing studies of Cygnus X-1 in the low/hard and hard intermediate state were conducted in a model-independent manner, using broadband Suzaku data acquired on 25 occasions from 2005 to 2009 with a total exposure of ~ 450 ks. The unabsorbed 0.1--500 keV source luminosity changed over 0.8--2.8% of the Eddington limit for 14.8 solar masses. Variations on short (1--2 seconds) and long (days to months) time scales require at least three separate components: a constant component localized below ~2 keV, a broad soft one dominating in the 2--10 keV range, and a hard one mostly seen in 10--300 keV range. In view of the truncated disk/hot inner flow picture, these are respectively interpreted as emission from the truncated cool disk, a soft Compton component, and a hard Compton component. Long-term spectral evolution can be produced by the constant disk increasing in temperature and luminosity as the truncation radius decreases. The soft Compton component likewise increases, but the hard Compton does not, so that the spectrum in the hard intermediate state is dominated by the soft Compton component; on the other hand, the hard Compton component dominates the spectrum in the dim low/hard state, probably associated with a variable soft emission providing seed photons for the Comptonization.
Astrophysical black holes are ideal laboratories for testing Einstein's theory of general relativity in the strong field regime. In this manuscript, we present an analysis of Suzaku and NuSTAR spectra of the black hole binary Cygnus X-1 using RELXILL_NK. Unlike our previous study on Cygnus X-1 with NuSTAR data, here we are able to constrain the Johannsen deformation parameter $α_{13}$. However, despite the high energy resolution near the iron line provided by Suzaku, our constraints on the Kerr metric from Cygnus X-1 are not very stringent in comparison with those that have been obtained from …
Highly Ionized Fe-K Absorption Line from Cygnus X-1 in the High/Soft State Observed with Suzaku
2011年10月5日，在高/软状态期间，我们在朱雀观测的天鹅座黑洞X-1的高级会合附近观测到了一条瞬态类He Fe K α吸收线，这使我们能够首次绘制出从幕式吸积现象或下降开始和结束的完整演化。我们在事件中的X射线光谱模型，并跟踪其演变。吸收线在观测的前半部分相当弱，但在~10 ks时立即加深，之后减弱。等效宽度的总体变化是~3的因子，在~0.08的轨道相位处达到峰值。这是为黑洞提供能量的伴星风是星云的证据。通过分析与Voigt配置文件的线，它被发现是符合轻微红移的Fe XXV过渡，或可能是几个物种的混合物比Fe XXV少电离。这些数据可以用一个距离约为10^（10-12）cm、密度约为10^（（-13）-（-11））g cm^-3的团块来解释，该团块吸积到黑洞上，并/或通过视线到达黑洞，导致观测到的电离度瞬间下降和/或吸积物质密度增加。通过未来的X射线量热计任务（如ASTRO-H和AXSIO）继续监测个别事件，将使我们能够详细绘制出吸积环境及其在各种吸积状态之间的变化。
We present a new analysis of NuSTAR and Suzaku observations of the black hole Cygnus X-1 in the intermediate state. The analysis uses kerrC, a new model for analyzing spectral and spectropolarimetric X-ray observations of black holes. kerrC builds on a large library of simulated black holes in X-ray binaries. The model accounts for the X-ray emission from a geometrically thin, optically thick accretion disk, the propagation of the X-rays through the curved black hole spacetime, the reflection off the accretion disk, and the Comptonization of photons in coronae of different 3-D shapes and physi…
We perform two-dimensional particle-in-cell simulations of magnetic reconnection in electron-ion plasmas subject to strong Compton cooling and calculate the X-ray spectra produced by this process. The simulations are performed for trans-relativistic reconnection with magnetization $1\leq σ\leq 3$ (defined as the ratio of magnetic tension to plasma rest-mass density), which is expected in the coronae of accretion disks around black holes. We find that magnetic dissipation proceeds with inefficient energy exchange between the heated ions and the Compton-cooled electrons. As a result, most electr…
