4U 1543-475 长软态中嵌入的射电耀发与 X 射线硬化
Radio flares and X-ray hardening embedded in the long soft state of 4U 1543-475
AI总结：
本研究通过多波段观测，揭示黑洞 X 射线双星 4U 1543-475 2021 年爆发期间的射电耀发与 X 射线硬化现象，明确其与吸积流几何、冕辐射及喷流的复杂关联。
AI中文摘要：
我们对黑洞 X 射线双星 4U 1543-475 在 2021 年爆发期间开展了全面的多波段研究，重点关注射电耀发事件——这类事件通常被解释为间歇性喷流产生的信号，且嵌入于 X 射线辐射由吸积盘成分主导的态中。射电监测显示至少存在两次离散耀发，它们与康普顿化 X 射线辐射增强的时期重合。宽带光谱建模表明，这些耀发期间反射成分与吸积盘的流量比显著降低（约 3-4 倍），这与内吸积流几何的临时变化一致，但数据无法明确确立因果序列。光学测光表现出的变异性大致跟踪反射成分，与辐射源的变化相符。伴随的光谱硬化表明，射电耀发与向“更硬”态的短暂偏移相关，偏离了软态。X 射线计时分析显示，射电耀发可能与均方根变异性的分数变化相关，但不同事件间无法确立一致或统一的模式。这些结果提供了黑洞双星中射电耀发活动的多波段观测实例，并凸显了吸积流几何、冕辐射与喷流相关现象之间的复杂相互作用。
英文摘要：
We present a comprehensive multi-wavelength study of the black hole X-ray binary 4U 1543-475 during its 2021 outburst, focusing on radio flaring episodes that are commonly interpreted as signatures of episodic jet production and are embedded within states when the X-ray emission was dominated by an accretion disk component. The radio monitoring reveals at least two discrete flares that coincide with periods of enhanced Comptonized X-ray emission. Broadband spectral modelling shows a significant decrease in the reflection-to-disk flux ratio (by a factor of ~3-4) during these episodes, consistent with a temporary change in the geometry of the inner accretion flow, although the data do not allow the causal sequence to be firmly established. Optical photometry exhibits variability that broadly tracks the reflection fraction, consistent with changes in the illuminating component. The accompanying spectral hardening indicates that the radio flares were associated with short-lived excursions toward a "harder" state, departing from the soft state. X-ray timing analysis suggests that the radio flares may be associated with changes in the fractional rms variability; however, no consistent or unified pattern can be firmly established across different events. These results provide a multi-wavelength observational example of radio flaring activity in a black hole binary and highlight the complex interplay between accretion flow geometry, coronal emission, and jet-related phenomena.
