论文标题
幂律进化中的相对论效应和GRB极化
Relativistic Effects and GRB Polarization in Power-Law Evolution
论文作者
论文摘要
尽管数十年的极化观测和高显着性极化$γ$ -Ray,X射线,光学,光学和无线电发射(GRB)在数十个案例中已经积累了,但人们尚未找到一个一致的场景,以了解GRB极化的全球定时属性。在这里,我们报告说,观察到的GRB极化特性在宇宙学距离处表现出四段的定时演化:(i)早期(在前几秒钟内)的初始驼峰; (ii)以后的power-law衰减(从$ \ sim $ 10 $^{1} $到$ \ sim $ 10 $^{4} $ s),它采用$π_ {\ rm obs} \ propto t^{ - 0.50 \ 0.50 \ pm pm 0.02} $的形式(iii)之后延迟重新布置驼峰(从$ \ sim $ 10 $^{4} $到$ \ sim $ 10 $^{5} $ s); (iv)最后一个扁平的幂律衰减(从$ \ sim $ 10 $^{5} $到$ \ sim $ 10 $^{7} $ s),其形式的形式为$π_ {\ rm obs} \ propto t^{ - 0.21 \ 0.21 \ pm 0.08} $。这些发现可能会给极化模型的主流带来挑战,这些模型假设不同发射区域的极化时间演化变化。我们表明,这些结果可以通过中央发动机产生的高度相对论和磁化射流的相对论和几何影响以及“磁贴”分布为全球随机但局部相干形式的“磁贴”。我们的分析表明,有一种单一的主要机制可能解释了GRB极化的全球观察性特性,而其他发射机制和效果可能在空间局部和时间上对GRB极化作用起作用。
Despite decades of polarization observations and high-significance polarized $γ$-ray, X-ray, optical, and radio emissions in gamma-ray bursts (GRBs) have been accumulating in dozens of cases, people have yet to find a consistent scenario for understanding the globally observed timing properties of GRB polarization to date. Here, we report that the observed properties of GRB polarization exhibit a four-segment timing evolution at the cosmological distance: (I) an initial hump early on (within the first few seconds); (II) a later on power-law decay (from $\sim$10$^{1}$ to $\sim$10$^{4}$ s), which takes the form of $π_{\rm obs} \propto t^{-0.50 \pm 0.02}$; (III) afterwards a late-time rebrightening hump (from $\sim$10$^{4}$ to $\sim$10$^{5}$ s); and (IV) finally a flatting power-law decay (from $\sim$ 10$^{5}$ to $\sim$ 10$^{7}$ s), with the the form of $π_{\rm obs} \propto t^{-0.21 \pm 0.08}$. These findings may present a challenge to the mainstream of polarization models that assume the polarization time evolution change in different emission regions. We show that these results can be explained by relativistic and geometric effects of a highly relativistic and magnetized jet generated by the central engine, and "magnetic patches" distributed as a globally random but locally coherent form. Our analysis suggests that there is a single dominant mechanism that might account for the global observational properties of GRB polarization, and other emission mechanisms and effects might play a role in spatially local and temporally short effects on GRB polarization.