标题： SOMA-POL调查。 I. 大质量原恒星的偏振和磁场特性 显示英文标题

标题： The SOMA-POL Survey. I. Polarization and magnetic field properties of massive protostars

摘要： 磁场在调控大质量恒星形成中的作用仍然存在很大争议。 在这里，我们展示了使用JCMT-POL2在$850\:\mu$米波长对从SOFIA大质量（SOMA）恒星形成调查中选择的13个大质量恒星形成区域进行的亚毫米极化观测，得到了总共29个大质量原恒星。 我们对$p'-I$关系的研究表明，尘粒对齐一直持续到最高强度。 我们检查了极化推断的磁场方向与源柱密度延伸方向在小尺度和大尺度上的相对取向。 在小尺度上，我们发现这些相对取向呈双峰分布，即近平行和近垂直取向过剩。 通过应用单样本Kuiper检验和蒙特卡洛模拟与从均匀分布中抽取的相对取向分布进行比较，我们统计确认了这种双峰分布，而不管测量结构取向的方法如何。 这种双峰分布表明磁场在大质量原恒星核的局部尺度（$\lesssim 0.6\:$光年）上是动态重要的。 我们还研究了整体偏振度和偏振矢量方向的局部分散性等基本偏振特性如何依赖于从光谱能量分布（SED）建模中推断出的原恒星固有属性。 我们发现去偏置偏振分数与光度与质量比，$L_{\rm bol}/M_{\rm env}$之间存在统计显著的负相关，这暗示了不同演化阶段的原恒星物体的尘埃性质发生了变化。 显示英文摘要

摘要： The role of magnetic fields in regulating the formation of massive stars remains much debated. Here we present sub-millimeter polarimetric observations with JCMT-POL2 at $850\:\mu$m of 13 regions of massive star formation selected from the SOFIA Massive (SOMA) star formation survey, yielding a total of 29 massive protostars. Our investigation of the $p'-I$ relationship suggests that grain alignment persists up to the highest intensities. We examine the relative orientations between polarization-inferred magnetic field direction and source column density elongation direction on small and large scales. On small scales, we find a bimodal distribution of these relative orientations, i.e., with an excess of near-parallel and near-perpendicular orientations. By applying a one-sample Kuiper test and Monte Carlo simulations to compare to a relative orientation distribution drawn from a uniform distribution, we statistically confirm this bimodal distribution, independent of the methods to measure structural orientation. This bimodal distribution suggests that magnetic fields are dynamically important on the local scales ($\lesssim 0.6\:$pc) of massive protostellar cores. We also examine how basic polarization properties of overall degree of polarization and local dispersion in polarization vector orientations depend on intrinsic protostellar properties inferred from spectral energy distribution (SED) modeling. We find a statistically significant anti-correlation between the debiased polarized fraction and the luminosity to mass ratio, $L_{\rm bol}/M_{\rm env}$, which hints at a change in the dust properties for protostellar objects at different evolutionary stages.