PORTAL --三维偏振（亚）毫米线辐射转移
PORTAL--three-dimensional polarized (sub)millimeter line radiative transfer
摘要：
上下文磁场对许多天体物理过程的动力学很重要，通常可以通过偏振观测进行研究。现代（亚）毫米望远镜设施的偏振干涉测量能力，使人们有可能获得详细的速度分辨分子线偏振图。为了正确地分析它们所携带的关于磁场的信息，开发自适应三维极化线辐射转移模型是必要的。目标。我们的目标是开发一个易于使用的程序来模拟磁化天体物理区域，如原恒星盘，拱星信封，或分子云的分子和原子（亚）毫米线的偏振图。方法.通过考虑辐射场的局部各向异性作为唯一的取向机制，我们可以通过仅利用该模拟的收敛输出来模拟规则线辐射转移模拟内的分子或原子物种的取向。随后可以使用对齐的分子或原子状态的计算来对三维模拟的偏振图进行射线追踪。结果我们提出了一个三维辐射转移代码，适应线的极化辐射转移（PORTAL），它可以模拟通过任意形态的磁场的线发射中极化的出现。我们的模型可以在独立模式下使用，假设LTE激发，但它是最好的使用时，处理定期的三维（非偏振）线辐射转移建模代码的输出。我们提出了光谱偏振图的测试情况下的坍缩球和原行星盘的多个三维磁场形态。
英文摘要：
Context. Magnetic fields are important to the dynamics of many astrophysical processes and can typically be studied through polarization observations. Polarimetric interferometry capabilities of modern (sub)millimeter telescope facilities have made it possible to obtain detailed velocity resolved maps of molecular line polarization. To properly analyze these for the information they carry regarding the magnetic field, the development of adaptive three-dimensional polarized line radiative transfer models is necessary. Aims. We aim to develop an easy-to-use program to simulate the polarization maps of molecular and atomic (sub)millimeter lines in magnetized astrophysical regions, such as protostellar disks, circumstellar envelopes, or molecular clouds. Methods. By considering the local anisotropy of the radiation field as the only alignment mechanism, we can model the alignment of molecular or atomic species inside a regular line radiative transfer simulation by only making use of the converged output of this simulation. Calculations of the aligned molecular or atomic states can subsequently be used to ray trace the polarized maps of the three-dimensional simulation. Results. We present a three-dimensional radiative transfer code, POlarized Radiative Transfer Adapted to Lines (PORTAL), that can simulate the emergence of polarization in line emission through a magnetic field of arbitrary morphology. Our model can be used in stand-alone mode, assuming LTE excitation, but it is best used when processing the output of regular three-dimensional (nonpolarized) line radiative transfer modeling codes. We present the spectral polarization map of test cases of a collapsing sphere and protoplanetary disk for multiple three-dimensional magnetic field morphologies.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
