发表机构
University of Helsinki; University of Nevada, Las Vegas; Columbia University; Flatiron Institute（赫尔辛基大学; 内华达大学拉斯维加斯分校; 哥伦比亚大学; 平顿研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过三维粒子模拟揭示相对论磁化激波同步加速器脉泽辐射的光谱带宽与高线偏振特性，为区分非重复快速射电暴的辐射机制提供可检验特征。
AI 中文摘要
快速射电暴（FRBs）是毫秒级射电瞬变现象，其辐射机制仍是一个悬而未决的问题。相对论磁化激波中的所谓同步加速器脉泽不稳定性是解释致密天体磁层外产生FRBs的主要候选机制，然而其光谱和偏振预测尚未被系统探索。我们呈现了上游磁化参数σ>1、体洛伦兹因子γ0=10的相对论磁化对等离子体激波的三维粒子模拟，假设平面平行激波几何并忽略辐射冷却，计算了任意视线方向上前驱脉泽辐射的光谱和偏振。对于与激波传播方向对齐的轴上观测者，X模主导辐射。O模功率在离轴视角下增加，主要与平行于上游背景磁场的电流相关。假设球形激波，我们发现σ=3和6时半高全宽分数带宽分别为Δν/ν0≃0.57和0.82。对于高磁化激波，固有辐射带宽占光谱宽度的大部分，而高纬度贡献提供额外展宽。积分辐射在光谱峰值附近保持高度线偏振，由于X模的主导地位，偏振角几乎恒定。我们的结果表明，同步加速器脉泽辐射可以产生与某些非重复FRBs观测相符的带宽和高度线偏振度光谱，并可能提供可检验的特征以区分激波驱动的FRBs与其他辐射机制。
英文摘要
Fast radio bursts (FRBs) are millisecond-duration radio transients whose emission mechanism remains an open question. The so-called synchrotron maser instability in relativistic magnetized shocks is a leading candidate for FRBs produced outside the compact object magnetosphere, yet its spectral and polarization predictions have not been systematically explored. We present three-dimensional particle-in-cell simulations of relativistic magnetized pair plasma shocks with upstream magnetization $σ> 1$ and bulk Lorentz factor $γ_0 = 10$, assuming a plane-parallel shock geometry and neglecting radiative cooling, and compute the spectra and polarization of the precursor maser emission for an arbitrary line of sight. For on-axis observers aligned with the shock-propagation direction, the X-mode dominates the emission. The O-mode power increases at off-axis viewing angles and is primarily associated with currents parallel to the upstream background magnetic field. Assuming a spherical shock, we find full-width-at-half-maximum fractional bandwidths of $Δν/ν_0\simeq0.57$ and $0.82$ for $σ=3$ and $6$, respectively. For highly magnetized shocks, the intrinsic emission bandwidth accounts for most of the spectral width, while high-latitude contributions provide additional broadening. The integrated emission remains highly linearly polarized near the spectral peak, with a nearly constant polarization angle due to the dominance of the X-mode. Our results suggest that synchrotron maser emission can produce spectra with bandwidths and high linear polarization degrees compatible with observations of some non-repeating FRBs, and may provide testable signatures for distinguishing shock-powered FRBs from other emission mechanisms.
Comments17 pages, 8 figures
