论文标题
Nustar明亮的活跃银河核中的X射线冠
The X-ray coronae in NuSTAR bright active galactic nuclei
论文作者
论文摘要
我们对Nustar数据进行了系统和统一的分析，该数据具有10-78 keV S/n> 50，对60个Swift BAT选定的AGN样本进行了系统，其中10个是无线电大声的。我们使用三种不同的光谱模型来测量其高能量截断或冠状温度TE，以适应其Nustar光谱，并显示Nustar光谱S/N中的阈值对于此类测量至关重要。在大多数样品中都检测到高能频谱断裂，并且对于其余的，对ECUT或TE的强大限制。令人惊讶的是，我们发现10个无线电广场来源中的较大的下限（> 400 keV，> 800 keV），而在无线电大风样品中则没有。因此，令人惊讶的是，我们发现与无线电大声播放的射电源的平均ecut/te明显更大。通过模拟仔细检查和验证这些测量值的可靠性。我们发现ECUT和光子指数γ之间存在很强的正相关性，这不能归因于参数退化。 ECUT对γ的强烈依赖性，这可以完全解释无线电和射电源之间的ECUT分布的差异，这表明具有较高的硬X射线光谱的AGN中的X射线冠状器平均具有较高的温度，因此更小。但是，在ECUT和λEDD之间没有发现明显的相关性。在L-θ图中，我们发现由于失控的生产而导致禁止区域的边界超出了相当一部分的来源，对各种（平坦的）冠状几何形状提出了（更强的）挑战。
We present systematic and uniform analysis of NuSTAR data with 10-78 keV S/N > 50, of a sample of 60 SWIFT BAT selected AGNs, 10 of which are radio-loud. We measure their high energy cutoff Ecut or coronal temperature Te using three different spectral models to fit their NuSTAR spectra, and show a threshold in NuSTAR spectral S/N is essential for such measurements. High energy spectral breaks are detected in the majority of the sample, and for the rest strong constraints to Ecut or Te are obtained. Strikingly, we find extraordinarily large Ecut lower limits ( > 400 keV, up to > 800 keV) in 10 radio-quiet sources, whereas none in the radio-loud sample. Consequently and surprisingly, we find significantly larger mean Ecut/Te of radio-quiet sources compared with radio-loud ones. The reliability of these measurements are carefully inspected and verified with simulations. We find a strong positive correlation between Ecut and photon index Γ, which can not be attributed to the parameter degeneracy. The strong dependence of Ecut on Γ, which could fully account for the discrepancy of Ecut distribution between radio-loud and radio-quiet sources, indicates the X-ray coronae in AGNs with steeper hard X-ray spectra have on average higher temperature and thus smaller opacity. However, no prominent correlation is found between Ecut and λedd. In the l-Θ diagram, we find a considerable fraction of sources lie beyond the boundaries of forbidden regions due to runaway pair production, posing (stronger) challenges to various (flat) coronal geometries.
