We study the X-ray spectral evolution of quasars with red-shift using a sample of 1280 quasars constructed by cross-referencing the XMM-Newton $3XMM-DR7$ and the optical SDSS-DR14 catalogues. The sources were selected to have a minimum detected X-ray counts >600 and which were not affected by high background. The sample redshift distribution ranges from 0-4.9 and peaks around 1. For each source, the XMM-Newton EPIC_PN spectra were generated and fitted with a power-law model with Galactic absorption. Consistent with some earlier results we find a strong correlation between the photon index and redshift. We explicitly test the hypothesis that this is due to the X-ray soft excess and reflection bump being red-shifted away from the XMM band, by adding a black body and reflection component and find that the correlation is no longer significant. Thus, for the first time, we show that there is no evidence for quasar spectral evolution and the correlation between index and red-shift is indeed due to the soft excess and reflection component.

我们使用通过交叉参考 XMM-牛顿构造的 1280 个类星体样本研究了红移类星体的 X 射线光谱演化 $3X米米-D\mathrm{电阻}7$和光学 SDSS-DR14 目录。选择具有最小检测到的 X 射线计数 >600 且不受高背景影响的源。样本红移分布范围为 0-4.9，峰值约为 1。对于每个源，生成 XMM-牛顿 EPIC_PN 光谱并拟合具有银河吸收的幂律模型。与一些早期的结果一致，我们发现光子指数和红移之间存在很强的相关性。我们通过添加黑体和反射分量，明确地检验了这是由于 X 射线软过剩和反射凸点从 XMM 波段红移所致的假设，并发现相关性不再显着。于是，第一次，