论文标题
搜索Seyfert星系中的冠状温度变化
Search for coronal temperature variation in Seyfert galaxies
论文作者
论文摘要
尽管活性银河核（AGN）中X射线电晕的温度（$ \ rm {kt_e} $）以许多来源而闻名，但其变化（如果有）仅限于少数物体。这部分是由于需要涵盖各种能量的良好信噪X射线光谱。我们在这里介绍了18个Seyferts的X射线光谱分析，其中有一个以上的观测值以寻找$ \ rm {kt_e} $的变化。这18个AGN的总计52个时代的数据是从Nustar在3 $ -79 KEV Energy Band中进行的观察结果获取的。从现象学和物理模型拟合到从{\ it nustar}的这18个来源上的多上述数据，我们可以在很大一部分来源中限制截止能量（$ e_ {cut} $）。另外，从组成的型号拟合中，我们可以为我们的样本获得$ \ rm {kt_e} $。在90％的置信度下，在18个来源中，仅发现一个来源，即MCG+08-11-011，发现了$ \ rm {kt_e} $变化的证据。对于这个来源，在两个时期之间，大约五年，我们发现$ \ rm {kt_e} $从57 $^{+29} _ { - 16} $ keV降低至30 $^{+11} _ { - 7} $ kev。在同一时期，通量从（12.60至14.02）$ \ times $ 10 $^{ - 11} $ erg cm $^{ - 2} $ s $ s $^{ - 1} $，光学深度从1.68增加到2.73。因此，我们发现通量和冠状温度之间存在正相关，光学深度降低了约40％。我们的观察结果倾向于在MCG+08-11-011中倾向于垂直流出的电晕场景，以$ \ rm {kt_e} $中观察到的变化。
While the temperature of the X-ray corona ($\rm{kT_e}$) in active galactic nuclei (AGN) are known for many sources, its variation, if any, is limited to a handful of objects. This is in part due to the requirement of good signal-to-noise X-ray spectra covering a wide range of energies. We present here results on the X-ray spectral analysis of 18 Seyferts, having more than one epoch of observations to look for variation in $\rm{kT_e}$. The data for a total of 52 epochs on these 18 AGN were taken from observations carried out by NuSTAR in the 3$-$79 keV energy band. From phenomenological and physical model fits to the multi-epoch data on these 18 sources from {\it NuSTAR}, we could constrain the cut-off energy ($E_{cut}$) in a large fraction of the sources. Also, from Comptonized model fits, we could obtain $\rm{kT_e}$ for our sample. Of the 18 sources, at the 90 per cent confidence level, evidence for variation in $\rm{kT_e}$ was found for only one source, namely MCG+08-11-011. For this source, between two epochs, separated by about five years, we found $\rm{kT_e}$ to decrease from 57$^{+29}_{-16}$ keV to 30$^{+11}_{-7}$ keV. During the same period, the flux decreased from (12.60 to 14.02) $\times$ 10$^{-11}$ erg cm$^{-2}$ s$^{-1}$ and the optical depth increased from 1.68 to 2.73. We thus found a positive correlation between flux and coronal temperature with a reduction of about 40 per cent in optical depth. Our observations tend to favour the vertically outflowing corona scenario for the observed variation in $\rm{kT_e}$ in MCG+08-11-011.
