AI 中文总结
该研究针对延展极端相对论性源的曲率辐射，推导其光谱与偏振相干特性，发现光谱退相干可伴随无强去极化，或能解释特定高偏振快速射电暴。
AI 中文摘要
背景：快速射电暴常表现出强线偏振与显著光谱结构，但在相干曲率辐射中，光谱退相干与去极化未必同时发生。目标：研究来自延展极端相对论性源的曲率辐射的光谱与偏振相干性。方法：采用相干矩阵形式主义结合均匀发射延展源的渐近相位展开，推导曲率辐射的光谱与偏振相干特性。结果：光谱退相干与去极化受不同物理条件支配，演化尺度不同； retardation相位变化抑制光谱相干性，而偏振在相对论性聚束锥内基本保持，自然产生宽范围偏振但光谱退相干的区域，其范围随频率和洛伦兹因子增大而增加。结论：极端相对论性曲率辐射中自然出现无强去极化的光谱退相干，可解释具有强光谱调制或窄带结构的高偏振快速射电暴。
英文摘要
Context: Fast radio bursts often exhibit strong linear polarization together with pronounced spectral structure. Yet in coherent curvature radiation, spectral decoherence and depolarization are not necessarily simultaneous. Aims: We investigate spectral and polarization coherence in curvature radiation from extended ultrarelativistic sources. Methods: Using the coherency matrix formalism together with an asymptotic phase expansion for a uniformly emitting extended source, we derive the spectral and polarization coherence properties of curvature radiation. Results: We show that spectral decoherence and depolarization are governed by distinct physical conditions and therefore develop on separate scales. Retardation phase variations suppress spectral coherence, whereas polarization remains largely preserved across the relativistic beaming cone, naturally producing a broad polarized but spectrally decoherent regime whose extent increases toward higher frequencies and larger Lorentz factors. Conclusions: Spectral decoherence without strong depolarization naturally arises in ultrarelativistic curvature radiation and may explain highly polarized fast radio bursts with strong spectral modulation or narrow band structure.
CommentsAccepted for publication in Astronomy and Astrophysics (Letter)
