Relativistically blueshifted absorption features of highly ionised ions, the so-called ultra-fast outflows (UFOs), have been detected in the X-ray spectra of a number of accreting supermassive black holes. If these features truly originate from accretion disc winds accelerated to more than 10 per cent of the speed of light, their energy budget is very significant and they can contribute to or even drive galaxy-scale feedback from active galactic nuclei (AGN). However, the UFO spectral features are often weak due to high ionisation of the outflowing material, and the inference of the wind physical properties can be complicated by other spectral features in AGN such as relativistic reflection. Here we study a highly accreting Narrow Line Seyfert 1 galaxy PG 1448+273. We apply an automated, systematic routine for detecting outflows in accreting systems and achieve an unambiguous detection of a UFO in this AGN. The UFO absorption is observed in both soft and hard X-ray bands with the XMM-Newton observatory. The velocity of the outflow is (26900 +- 600) km/s (~0.09c), with an ionisation parameter of log ({\xi} / erg cm s^-1)=4.03_{-0.08}^{+0.10} and a column density above 10^23 cm^-2. At the same time, we detect weak warm absorption features in the spectrum of the object. Our systematic outflow search suggests the presence of further multi-phase wind structure, but we cannot claim a significant detection considering the present data quality. The UFO is not detected in a second, shorter observation with XMM-Newton, indicating variability in time, observed also in other similar AGN.

中文翻译：

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在窄线赛弗特 1 星系 PG 1448+273 中检测到可变的超快外流

在许多吸积超大质量黑洞的 X 射线光谱中，已检测到高度电离离子的相对论蓝移吸收特征，即所谓的超快流出 (UFO)。如果这些特征真的源于加速到光速 10% 以上的吸积盘风，那么它们的能量预算非常重要，它们可以促进甚至驱动来自活动星系核 (AGN) 的星系级反馈。然而，由于流出物质的高度电离，UFO 的光谱特征通常很弱，并且风物理特性的推断可能会因 AGN 中的其他光谱特征（例如相对论反射）而变得复杂。在这里，我们研究了一个高度吸积的窄线赛弗特 1 星系 PG 1448+273。我们应用自动化，用于检测吸积系统中的外流并在此 AGN 中明确检测 UFO 的系统程序。使用 XMM-牛顿天文台在软和硬 X 射线波段中都观察到 UFO 吸收。流出速度为 (26900 +- 600) km/s (~0.09c)，电离参数为 log ({\xi} / erg cm s^-1)=4.03_{-0.08}^{+ 0.10} 和高于 10^23 cm^-2 的列密度。同时，我们在物体的光谱中检测到微弱的暖吸收特征。我们的系统流出搜索表明存在进一步的多相风结构，但考虑到目前的数据质量，我们不能声称进行了重大检测。使用 XMM-Newton 进行的第二次较短的观察中没有检测到 UFO，这表明时间上的可变性，在其他类似的 AGN 中也观察到。