AI 中文总结
本研究通过NuSTAR反射光谱分析26份观测样本，发现天鹅座X-1的圆盘内半径、铁丰度等参数依赖模型与状态，修正了此前关于圆盘截断程度及铁丰度的相关结论。
AI 中文摘要
天鹅座X-1的相对论反射测量在圆盘截断程度上存在分歧，且通常推断出超太阳铁丰度。我们分析了2012年至2024年间获取的26份存档NuSTAR观测样本，使用某反射模型族的两种构型，通过预条件序贯蒙特卡洛采样后验模态。在基线恢复模态中，圆盘表面电离度随光子指数升高而增加（皮尔逊相关系数r=+0.59），状态中位数从硬态的log ξ≈3.3上升至软态的≈3.9；对应的自由发射率拟合给出硬态、中间态、软态的内半径中位数分别为6.6、4.4、4.0 R_ISCO。固定q=3时，8次软态观测中有3次移至ISCO，1次移至2.4 R_ISCO；4次固定q的拟合比采样的自由q解具有更低的χ²，表明这些运行遗漏了更高似然区域。因此推断的半径依赖于模型和模态，且光谱既不要求也不排除ISCO圆盘或R_in大于或约20 R_ISCO。基线拟合的丰度范围为A_Fe=1.6-8.6，中位数为4.9；间隔7.2小时的两次观测给出A_Fe=1.9±0.2和4.5±1.0，表明拟合丰度并非直接的成分测量。固定A_Fe=1.6会使部分密度趋向网格边界，且相较于A_Fe=4.5的拟合效果更差；风参数仍对连续谱、丰度和轨道相位采样敏感。
英文摘要
Relativistic-reflection measurements of Cygnus X-1 disagree on the extent of disk truncation and commonly infer supersolar iron abundances. We analyze a selected sample of 26 archival NuSTAR observations obtained between 2012 and 2024 using two configurations from one reflection-model family, with posterior modes sampled by preconditioned sequential Monte Carlo. In the baseline recovered modes, disk-surface ionization increases with photon index (Pearson r = +0.59), with state medians rising from log xi approximately 3.3 in the hard state to approximately 3.9 in the soft state. The corresponding free-emissivity fits give median inner radii of 6.6, 4.4, and 4.0 R_ISCO in the hard, intermediate, and soft states. Fixing q = 3 moves three of eight soft-state observations to the ISCO and one to 2.4 R_ISCO; four fixed-q fits have lower chi^2 than the sampled free-q solutions, showing that those runs missed higher-likelihood regions. The inferred radii are therefore model- and mode-dependent, and the spectra neither require nor exclude an ISCO disk or R_in greater than or approximately 20 R_ISCO. Baseline fitted abundances span A_Fe = 1.6-8.6, with a median of 4.9. Two observations separated by 7.2 hr yield A_Fe = 1.9 +/- 0.2 and 4.5 +/- 1.0, indicating that fitted abundance is not a direct composition measurement. Fixing A_Fe = 1.6 drives some densities toward the grid boundary and worsens the fits relative to A_Fe = 4.5. The wind parameters remain sensitive to the continuum, abundance, and orbital-phase sampling.
CommentsUnder review at ApJ. v2: Fixed author order
