持续大质量X射线双星与超巨星快速暂现源中超巨星供体的光度等级二分证据
Evidence for a luminosity-class dichotomy in the supergiant donors of persistent high-mass X-ray binaries and supergiant fast X-ray transients
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中文总结 AI 辅助
该研究通过构建可靠样本发现，呈现极端暂现X射线辐射的SFXTs仅含Ib/Iab光度级的O/B型超巨星，而经典HMXBs多含Ia型供体，证实恒星光度等级二分或可解释两类HMXBs的X射线行为差异。
中文摘要 AI 辅助
我们通过收集文献中所有可用信息，研究了两类大质量X射线双星（HMXBs，即所谓超巨星快速暂现源（SFXTs）与经典X射线源）中超巨星供体的性质。此前文献曾提出SFXTs中O型超巨星供体占比高于B型，这可能表明SFXTs的星风比经典持续源更快。由于已知SFXTs中也存在B型超巨星，我们的目标是探究是否存在恒星光度等级的二分证据。我们收集相关文献后构建了两类HMXBs的可靠样本，且恒星分类明确。我们发现，呈现最极端暂现X射线辐射的SFXTs仅拥有Ib和Iab光度级的O型或B型恒星，而经典源则大多拥有Ia型供体。这一可靠证据或可解释HMXBs在X射线波段的两种不同行为，因为恒星光度等级似乎与星风性质（超巨星星风终速、质量损失率及星风强度Q参数）相关，表明SFXTs的星风比经典源更快且密度更低。
英文摘要
We have investigated the properties of the supergiant donors in two types of high-mass X-ray binaries (HMXBs, i.e. the so-called supergiant fast X-ray transients (SFXTs) and the classical X-ray sources), by collecting all available information from the literature. A prevalence of O-type versus B-type supergiant donors in SFXTs was previously suggested in the literature, possibly indicative of faster winds in SFXTs than in classical, persistent sources. Our aim is to investigate whether there is evidence for a dichotomy in the stellar luminosity class, since B-type supergiants are also known to be hosted in SFXTs. Our collection of the relevant literature allowed us to build a robust sample of both types of HMXBs with a secure stellar classification. We have found that the SFXTs showing the most extreme, transient X-ray emission host only O-type or B-type stars with a Ib and Iab luminosity class, whereas classical sources have mostly Ia donors. This is robust evidence that might explain the two different behaviours of HMXBs at X-rays since the stellar luminosity class appears to be linked to the wind properties (the supergiant wind terminal velocity, the mass-loss rate, and the wind strength Q parameter), indicative of faster and less dense winds in SFXTs than in classical sources.
发表机构
- INAF-IASF Milano, Istituto di Astrofisica Spaziale e Fisica Cosmica（意大利国家天体物理研究所米兰空间天体物理学与宇宙物理学研究所）
- INAF-OAS, Osservatorio di Astrofisica e Scienza dello Spazio（意大利国家天体物理研究所太空天体物理学与空间科学观测站）
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