We develop a novel statistical approach to identify emission features or set upper limits in high-resolution spectra in the presence of high background. The method relies on detecting differences from the background using smooth tests and using classical likelihood ratio tests to characterise known shapes like emission lines. We perform signal detection or place upper limits on line fluxes while accounting for the problem of multiple comparisons. We illustrate the method by applying it to a Chandra LETGS+HRC-S observation of symbiotic star RT Cru, successfully detecting previously known features like the Fe line emission in the 6-7 keV range and the Iridium-edge due to the mirror coating on Chandra. We search for thermal emission lines from Ne X, Fe XVII, O VIII, and O VII, but do not detect them, and place upper limits on their intensities consistent with a $\approx$1 keV plasma. We serendipitously detect a line at 16.93 $\unicode{x212B}$ that we attribute to photoionisation or a reflection component.

翻译：我们开发了一种新的统计方法,以在高背景条件下确定高分辨率光谱的排放特征或设定高分辨率光谱的上限。该方法依靠光滑测试和古典概率比测试来探测背景差异,以描述排放线等已知形状。我们进行信号探测或对线流设定上限,同时考虑多重比较问题。我们用该方法来说明该方法,将它应用到Chandra LETGS+HRC-S对共生恒星RT Cru的观测中,成功检测到6-7 keV范围内的Fe线排放和Chandra镜涂层产生的 ⁇ 。我们从Ne X、Fe XVII、O VIII和O VII中搜索热排放线,但没有检测它们,并且按照$\approx 1,Kev等离子体的强度设定上限。我们偶然地检测出一条线值为16.93 $unicode{x212B},我们归因于光化或反射组件的16.93美元。