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首页> 外文期刊>PASJ: Publications of the Astronomical Society of Japan >Suzaku and NuSTAR X-ray spectroscopy of γ?Cassiopeiae and HD?110432
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Suzaku and NuSTAR X-ray spectroscopy of γ?Cassiopeiae and HD?110432

机译：朱雀和NuSTAR X射线光谱的γ？Cassiopeiae和HD？110432

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γ?Cas and its dozen analogs comprise a small but distinct class of X-ray sources. They are early Be-type stars with an exceptionally hard thermal X-ray emission. The X-ray production mechanism has been under intense debate. Two competing ideas are (i)?the magnetic activities in the Be star and its disk, and (ii)?the mass accretion onto the unidentified white dwarf (WD). We adopt the latter as a working hypothesis and apply physical models developed to describe the X-ray spectra of classical WD binaries containing a late-type companion. Models of non-magnetic and magnetic accreting WDs were applied to γ?Cas and its brightest analog HD?110432 using the Suzaku and NuSTAR data. The spectra were fitted by the two models, including the Fe fluorescence and the Compton reflection in a consistent geometry. The derived physical parameters are in a reasonable range in comparison to their classical WD binary counterparts. Additional pieces of evidence in the X-ray spectra—partial covering, Fe?L lines, Fe?i fluorescence—were not conclusive enough to classify these two sources into a subclass of accreting WD binaries. We discuss further observations, especially long-term temporal behaviors, which are important to elucidate the nature of these sources, if indeed they host accreting WDs.
机译：γ？Cas及其十二种类似物构成一小类但截然不同的X射线源。它们是早期Be型恒星，具有异常坚硬的X射线辐射。 X射线产生机制一直处于激烈的争论之中。两个相互竞争的想法是（i）“ Be星及其盘中的磁活动”，以及（ii）“积聚”在未识别的白矮星（WD）上。我们采用后者作为工作假设，并应用开发的物理模型来描述包含后期类型同伴的经典WD双星的X射线光谱。使用Suzaku和NuSTAR数据，将非磁性和磁性积聚WD的模型应用于γ？Cas及其最亮的模拟HD？110432。光谱由两个模型拟合，包括铁荧光和康普顿反射的几何形状一致。相较于其经典的WD二进制参数，得出的物理参数在合理范围内。 X射线光谱中的其他证据（部分覆盖，Fe？L谱线，Fe？i荧光）尚无定论，不足以将这两种来源归类为可吸收的WD二元类。我们将讨论进一步的观察结果，尤其是长期的时间行为，这对于阐明这些来源的性质（如果确实包含可分泌的WD）很重要。

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