论文标题
nustar硬X射线光谱
NuSTAR hard X-ray spectra of radio galaxies
论文作者
论文摘要
Nustar天文台及其3-78 KEV宽带光谱覆盖范围，可以在许多活动星系中检测到高能量截止，包括几个单独的无线电大声。在这项工作中，我们对28个射电星系的大量样本进行了55个Nustar光谱的系统和统一分析，其中20个是FR II星系。我们执行光谱拟合以测量高能截止$ e_ {cut} $，光子索引$γ$，反射因子R和Fe K $α$ line等效宽度。 $ e_ {cut} $的测量为13个来源，其余的下限。我们发现那些$ e_ {cut} $ non-detections可能主要归因于其光谱中明显较小的净光子计数。这表明我们大多数样品的Nustar光谱都由热力电晕发射主导，并且样品的$ e_ {cut} $分布与文献中的无线电安静的分布没有区别。因此，与无线电安静来源相比，我们观察到的平淡的nustar光谱是由于喷气污染的不可能。与无线电安静相比，射电星系还显示出较弱的X射线反射（在R和Fe K $α$线EW中）。与无线电安静样本相结合，我们看到了R和EW之间的相关性，但散布相当大。值得注意的是，无线电响亮而安静的来源似乎遵循了常见的$γ$ - r相关趋势，为两个人群提供了流出的电晕模型，在这种种群中，较高的大量流出速度会产生较弱的反射和更平坦的X射线斜率。
NuSTAR observatory, with its 3 - 78 keV broadband spectral coverage, enables the detections of the high-energy cutoff in a number of active galaxies, including several individual radio loud ones. In this work we present systematic and uniform analyses of 55 NuSTAR spectra for a large sample of 28 radio galaxies, 20 of which are FR II galaxies. We perform spectral fitting to measure the high energy cut-off $E_{cut}$, photon index $Γ$, reflection factor R and Fe K$α$ line equivalent width. Measurements of $E_{cut}$ are given for 13 sources, and lower limits for the rest. We find those $E_{cut}$ non-detections could primarily be attributed to the obviously smaller net photon counts in their spectra. This indicates that the NuSTAR spectra of the majority of our sample are dominated by the thermal corona emission, and the $E_{cut}$ distribution of the sample is indistinguishable from that of a radio quiet one in literature. The flatter NuSTAR spectra we observed, comparing with radio quiet sources, are thus unlikely due to jet contamination. The radio galaxies also show weaker X-ray reflection (both in R and Fe K$α$ line EW) comparing with radio quiet ones. Combining with the radio quiet sample we see a correlation between R and EW, but with considerably large scatter. Notably, the radio loud and quiet sources appear to follow a common $Γ$ - R correlation trend, supporting the outflowing corona model for both populations in which higher bulk outflowing velocity yields weaker reflection and flatter X-ray slope.
