在尘埃升华半径处的吸收和在Seyfert星系H0557-385中X射线和光学分类之间的二分法
Absorption at the dust sublimation radius and the dichotomy between X-ray and optical classification in the Seyfert galaxy H0557-385
摘要：
本文分析了Seyfert 1星系H 0557 -385的多历元（1995-2010）X射线观测资料。在此分析中提出的丰富的数据表明，源表现出显着的光谱变化，从一个典型的未吸收的塞弗特1型光谱的康普顿薄吸收状态，在时间尺度上的~5年。光谱形状的这种极端变化可以归因于中性吸收介质的柱密度和覆盖分数的变化，从而衰减了中心连续源的发射。康普顿反射的内在核发射的证据存在于每个光谱中，虽然这一特征在低态光谱中最为突出，其中相关的Fe发射线复合物清晰可见。除了可变的吸收介质，一个温暖的吸收剂成分已被检测到在每个光谱状态。与2010年XMM-牛顿观测活动同时进行的光谱学检测到在X射线吸收事件期间存在宽光学发射线。从X射线和光谱学数据的分析来看，已经推断，X射线光谱的变化性是中心发射区被覆盖> 80%的源，平均柱密度为NH ~ 7 × 10 ^{23} cm^{-2}，位于宽线区之外，与中心源的距离与活动星系核的尘埃升华半径一致。
英文摘要：
In this work, the analysis of multi-epoch (1995-2010) X-ray observations of the Seyfert 1 galaxy H0557-385 is presented. The wealth of data presented in this analysis show that the source exhibits dramatic spectral variability, from a typical unabsorbed Seyfert 1 type spectrum to a Compton-thin absorbed state, on time scales of ~5 years. This extreme change in spectral shape can be attributed to variations in the column density and covering fraction of a neutral absorbing medium attenuating the emission from the central continuum source. Evidence for Compton reflection of the intrinsic nuclear emission is present in each of the spectra, though this feature is most prominent in the low-state spectra, where the associated Fe emission line complex is clearly visible. In addition to the variable absorbing medium, a warm absorber component has been detected in each spectral state. Optical spectroscopy concurrent with the 2010 XMM-Newton observation campaign have detected the presence of broad optical emission lines during an X-ray absorption event.From the analysis of both X-ray and optical spectroscopic data, it has been inferred that the X-ray spectral variability is a result of obscuration of the central emission region by a clumpy absorber covering >80 per cent of the source with an average column density of NH ~7x10^{23} cm^{-2}, and which is located outside the broad line region at a distance from the central source consistent with the dust sublimation radius of the AGN.
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