论文标题
NGC 1042 ULX1中的光谱变异性
Spectral variability in NGC 1042 ULX1
论文作者
论文摘要
我们使用Archival XMM-Newton和最近的Nustar观察结果报告了超小X射线源NGC 1042 ULX1中X射线光谱变异性。在长期演变中，来源显示了光谱硬度变化的趋势。不同XMM-Newton观测值的可变性在$ \ sim 1 $ keV之上突出。具有$ \ sim 0.2 $ keV的特征温度的凉爽热盘组件表明，在所有时期，NGC 1042 ULX1的光谱状态与超小状态源相似。光度和PowerLaw指数之间的明显抗相关表明，当源处于较明亮状态时，源会变得更加困难。可以想象，这与积聚率的变化，组合的强度，系统中的风/流出或变化的磁盘掩埋的表现有关。典型的硬性超型频谱表明，NGC 1042 ULX1通常是低倾斜度系统。光谱属性表明，与许多其他ULX一样，它们显示出左右的频谱曲率6-10 $ KEV，NGC 1042 ULX1可能是另一个恒星质量的超级埃德丁顿增生器。
We report X-ray spectral variability in an ultraluminous X-ray source NGC 1042 ULX1, using archival XMM-Newton and recent NuSTAR observations. In long-term evolution, the source has shown a trend of variation in spectral hardness. The variability in different XMM-Newton observations is prominent above $\sim 1$ keV. Cool thermal disk component with a characteristic temperature of $\sim 0.2$ keV manifests that the spectral state of NGC 1042 ULX1 in all epochs is similar to that of the ultraluminous state sources. An apparent anti-correlation between luminosity and powerlaw index demonstrates that the source becomes spectrally harder when it is in a brighter state. That is conceivably related to variation in accretion rate, strength of comptonization, wind/outflow in the system or a manifestation of varying disk occultation. Typical hard ultraluminous type spectra indicate that NGC 1042 ULX1 is a low inclination system in general. Spectral properties suggest that, like many other ULXs which show spectral curvature around $\sim 6-10$ keV, NGC 1042 ULX1 could be another stellar-mass super-Eddington accretor.
