PSR J1023+0038一个轨道周期内的快速光学光谱观测
Fast optical spectroscopic observations of PSR J1023+0038 over one orbital period
AI总结：
研究对过渡毫秒脉冲星PSR J1023+0038在亚光度盘状态进行高时间分辨率光学光谱观测，覆盖完整轨道周期，检测发射线特性变化及相关行为，发现不对称结构，为其短时间尺度行为提供新限制，支持吸积外流共存，多波长观测对建立联系至关重要。
AI中文摘要：
过渡毫秒脉冲星（tMSPs）是在旋转供能和吸积供能状态之间切换的中子星双星，是低质量X射线双星和毫秒射电脉冲星之间的关键联系。在其亚光度盘状态下，这些系统表现出复杂的变化，其起源仍有争议。我们展示了在亚光度盘状态下对tMSP PSR J1023+0038进行的高时间分辨率光学光谱观测。我们的数据集首次以分钟级的时间间隔覆盖了一个完整的轨道周期。我们在分钟时间尺度上检测到光学发射线主要特性（包括等效宽度（EW）和半高全宽（FWHM））的显著变化。这些量的时间演化比较显示出相关行为的迹象，一些FWHM最小值与EW的减小同时出现。这可能表明有物质从吸积盘内部区域喷出，可能与低模式转换有关。Hα和Hβ发射线的多普勒层析成像表明存在不对称发射结构，这与部分吸积物质被从系统中喷出的情景一致。此外，光学连续谱的变化与受辐照伴星可能的轨道调制一致，尽管其特征受观测条件限制。我们的结果为亚光度盘状态下tMSPs的短时间尺度行为提供了新的限制，并支持吸积和外流过程共存的情景。进一步的多波长观测，特别是包括同时的X射线覆盖，对于建立观测到的光学变化与高/低模式转换之间的直接联系至关重要。
英文摘要：
Transitional millisecond pulsars (tMSPs) are neutron-star binaries that switch between rotation-powered and accretion-powered states, providing a key link between low-mass X-ray binaries and millisecond radio pulsars. In their sub-luminous disc state, these systems exhibit complex variability whose origin is still debated. We present high-time-resolution optical spectroscopic observations of the tMSP PSR J1023+0038 obtained during its sub-luminous disc state. Our dataset covers for the first time a full orbital cycle at minute-timescale cadence. We detect significant variability in the main properties of the optical emission lines, including the equivalent width (EW) and full width at half maximum (FWHM), on timescales of minutes. A comparison between the temporal evolution of these quantities reveals indications of correlated behaviour, with some FWHM minima coinciding with decreases in the EW. This may point to episodes of matter ejection from the inner regions of the accretion disc, possibly associated with switches to low modes. The Doppler tomography of the H$α$ and H$β$ emission lines suggests the presence of asymmetric emission structures, consistent with a scenario in which part of the accreting material is expelled from the system. In addition, the optical continuum shows variability consistent with a possible orbital modulation associated with the irradiated companion star, although its characterisation is limited by the observing conditions. Our results provide new constraints on the short-timescale behaviour of tMSPs in the sub-luminous disc state and support scenarios in which accretion and outflow processes coexist. Further multiwavelength observations, particularly including simultaneous X-ray coverage, will be crucial to establish a direct link between the observed optical variability and the high/low mode switches.
