论文标题
中子恒星低质量X射线二进制AQL X-1中的UV/光学和X射线发射之间的连接
The connection between the UV/optical and X-ray emission in the neutron star low-mass X-ray binary Aql X-1
论文作者
论文摘要
低质量X射线二进制（LMXB）中的中子星和黑洞横跨电磁频谱。在不同波长下链接产生的排放可以提供有关积聚过程和任何相关流出的有价值的信息。在这项工作中，我们研究了中子星LMXB \源的同时X射线和紫外线/光学观测，该源在其2013年，2014年和2016年增生爆发期间使用Neil Gehrels Swift观测值获得。我们发现，在所有三个爆发期间，紫外/光学和X射线发射都密切相关。对于具有最好的迅速采样的2013年和2014年，我们发现在爆发的衰减（柔和状态）期间，紫外/光学和X射线通量之间的相关性要比上升期间（难以易于弱的状态）更陡峭。我们观察到紫外线/光学磁滞行为，可能与常见的X射线光谱磁滞模式有关。对于三个爆发的衰减，我们获得了一个相关指数，该指数无法直接由任何单个模型来解释。我们怀疑这是导致紫外线/光学排放的多个排放过程的结果，但我们讨论了替代解释。基于这些相关性，我们讨论哪些机制可能主导了AQL X-1的UV/光学发射。
Accreting neutron stars and black holes in low-mass X-ray binaries (LMXBs) radiate across the electromagnetic spectrum. Linking the emission produced at different wavelengths can provide valuable information about the accretion process and any associated outflows. In this work, we study simultaneous X-ray and UV/optical observations of the neutron star LMXB \source, obtained with the Neil Gehrels Swift Observatory during its 2013, 2014 and 2016 accretion outbursts. We find that the UV/optical and X-ray emission are strongly correlated during all three outbursts. For the 2013 and 2014 episodes, which had the best Swift sampling, we find that the correlation between the UV/optical and X-ray fluxes is significantly steeper during the decay (soft state) of the outburst than during the rise (hard-to-soft state). We observe an UV/optical hysteresis behaviour that is likely linked to the commonly known X-ray spectral hysteresis pattern. For the decays of the three outbursts we obtain a correlation index that cannot be directly explained by any single model. We suspect that this is a result of multiple emission processes contributing to the UV/optical emission, but we discuss alternative explanations. Based on these correlations, we discuss which mechanisms are likely dominating the UV/optical emission of Aql X-1.
